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.A chromosome is an organized structure of DNA and protein that is found in cells.^ Find this article online O'Keefe RT, Henderson SC, Spector DL (1992) Dynamic organization of DNA replication in mammalian cell nuclei: Spatially and temporally defined replication of chromosome-specific alpha-satellite DNA sequences.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ Chromatin The network of chromosomes, histones, and other proteins found in the eukaryotic nucleus during interphase.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Korenberg J. R. & Rykowski, M. C. Human genome organization: Alu, lines, and the molecular structure of metaphase chromosome bands.
  • The DNA sequence of human chromosome 21 : Article : Nature 20 September 2009 15:32 UTC www.nature.com [Source type: Academic]

.It is a single piece of coiled DNA containing many genes, regulatory elements and other nucleotide sequences.^ Transcriptional repressor A regulatory element that binds a DNA transcription control sequence to repress the transcription of genes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Operator A regulatory DNA sequence that controls the transcription of structural genes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Gene duplication The duplication of DNA sequences corresponding to genes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.Chromosomes also contain DNA-bound proteins, which serve to package the DNA and control its functions.^ Chromosomes of higher organisms ( eukaryotes ) contain DNA and protein.
  • CHROMOSOMES 19 January 2010 9:53 UTC www.tamu.edu [Source type: FILTERED WITH BAYES]

^ A chromosome is the structure in which DNA is packaged.
  • GeneTree - Y-DNA (Y chromosome DNA) 19 January 2010 9:53 UTC www.genetree.com [Source type: FILTERED WITH BAYES]

^ Protein synthesis is controlled by genes, which are contained on chromosomes .

The word chromosome comes from the Greek χρῶμα (chroma, color) and σῶμα (soma, body) due to their property of being very strongly stained by particular dyes.
.
Diagram of a duplicated and condensed metaphase eukaryotic chromosome.
^ During mitosis, DNA is condensed into visible chromosomes (prophase) that arrange at the cell midplane (metaphase), separate (anaphase), and decondense into the interphase.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.(1) Chromatid – one of the two identical parts of the chromosome after S phase.^ Chromatid One of the two daughter strands of a duplicated chromosome.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Uniparental disomy is the inheritance of two homologous chromosomes from one parent.
  • CHROMOSOME ABNORMALITIES: AUTOSOMES AND SEX CHROMOSOMES 19 January 2010 9:53 UTC www.carolguze.com [Source type: Academic]

^ Until one centromere becomes inactivated the new chromosome will have two active centromeres (dicentric).
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

.(2) Centromere – the point where the two chromatids touch, and where the microtubules attach.^ Kinetochore A pair of structures adjacent to the chromosomal centromere to which spindle microtubules attach.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

(3) Short arm. (4) Long arm.
.Chromosomes vary widely between different organisms.^ While the findings described above support the possibility of nonrandom proximity between chromosomes in fibroblast nuclei, the observed cell-to-cell variability emphasizes the probabilistic nature of these patterns.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ Genomic epidemiology The genome-wide study of the relation between genetic variation and disease.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Allotype A protein variant arising from genetic differences between individuals of the same species.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.The DNA molecule may be circular or linear, and can be composed of 10,000 to 1,000,000,000[1] nucleotides in a long chain.^ Try the empirical fact that there are no chemical or physical bonds along the linear chain of nucleotides within DNA that causes the information content (the sequence) to exist the way it does?
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

^ Base sequence The order of nucleotide bases in a DNA molecule.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Chromosome A structure that carries the heriditary information for an organism and consists of a long DNA molecule with associated proteins.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.Typically eukaryotic cells (cells with nuclei) have large linear chromosomes and prokaryotic cells (cells without defined nuclei) have smaller circular chromosomes, although there are many exceptions to this rule.^ Y Chromosome Down Syndrome Information: Causes of Down Syndrome Down syndrome is a chromosomal disorder in which there is an extra copy of chromosome 21 in the cells of the developing fetus.

^ There is a white background and patches, more or less circular, of gold and black, with each patch coming from the clone of one cell with only black or gold turned on.
  • CHROMOSOME ABNORMALITIES: AUTOSOMES AND SEX CHROMOSOMES 19 January 2010 9:53 UTC www.carolguze.com [Source type: Academic]

^ Mitosis The process of chromosome segregation that occurs during the division of eukaryotic cells.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.Furthermore, cells may contain more than one type of chromosome; for example, mitochondria in most eukaryotes and chloroplasts in plants have their own small chromosomes.^ We have one less chromosome than apes.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

^ Heterokaryon A cell with more than one nucleus.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ T1/2 cells containing   MeSH: Chromosomes, Human   [Hold mouse button down for author info.
  • WikiGenes - Chromosomes, Human 20 September 2009 15:32 UTC www.wikigenes.org [Source type: Academic]

.In eukaryotes, nuclear chromosomes are packaged by proteins into a condensed structure called chromatin.^ Protein tertiary structure The folding of a protein into a 3-D structure.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Satellite DNA Highly repetitive, non-transcribed DNA regions in eukaryotic chromosomes that have a different sedimentatin coefficient than other nuclear DNA. Scaffold The molecular core common to all members of a combinatorial library; also proteins that are instrumental in the assembly of large 3-D structures.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Recently eukaryotic nuclear introns have been found to encode proteins.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.This allows the very long DNA molecules to fit into the cell nucleus.^ Polycation conjugates are used to transport DNA into cells.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Biolistics The high-velocity injection of DNA-coated particles directly into tissues, cells, or organelles using a gene gun.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Electroporation is used to introduce DNA into cells.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.The structure of chromosomes and chromatin varies through the cell cycle.^ Significant increase in the incidence of chromosome aberrations was observed only in cultures treated during early and/or middle S phases of the cell cycle.
  • Fluoride's Mutagenicity (Genotoxicity) 19 January 2010 9:53 UTC www.fluoridealert.org [Source type: Academic]

^ While the findings described above support the possibility of nonrandom proximity between chromosomes in fibroblast nuclei, the observed cell-to-cell variability emphasizes the probabilistic nature of these patterns.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ Parkinson's disease , schizophrenia, and susceptibility to alcoholism Structure and linkage of the D2 dopamine receptor and neural cell adhesion molecule genes on human chromosome 11q23.
  • WikiGenes - Chromosomes, Human 20 September 2009 15:32 UTC www.wikigenes.org [Source type: Academic]

.Chromosomes are the essential unit for cellular division and must be replicated, divided, and passed successfully to their daughter cells so as to ensure the genetic diversity and survival of their progeny.^ A centimorgan is a unit of genetic mapping equal to 1% crossover of genes between homologous chromosomes as established by genetic studies.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Cell division cycle The DNA synthesis pattern in dividing cells.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Females with translocations involving the X chromosome and autosomes will at first randomly inactive the X P or the X M but if one of the resulting cell lines results in too much genetic imbalance, it will die out.
  • CHROMOSOME ABNORMALITIES: AUTOSOMES AND SEX CHROMOSOMES 19 January 2010 9:53 UTC www.carolguze.com [Source type: Academic]

.Chromosomes may exist as either duplicated or unduplicated—unduplicated chromosomes are single linear strands, whereas duplicated chromosomes (copied during synthesis phase) contain two copies joined by a centromere.^ Chromatid One of the two daughter strands of a duplicated chromosome.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Significant increase in the incidence of chromosome aberrations was observed only in cultures treated during early and/or middle S phases of the cell cycle.
  • Fluoride's Mutagenicity (Genotoxicity) 19 January 2010 9:53 UTC www.fluoridealert.org [Source type: Academic]

^ A female is normally a mosaic of two cell populations, each expressing gene alleles from either their paternal or their maternal X chromosome.
  • CHROMOSOME ABNORMALITIES: AUTOSOMES AND SEX CHROMOSOMES 19 January 2010 9:53 UTC www.carolguze.com [Source type: Academic]

.Compaction of the duplicated chromosomes during mitosis and meiosis results in the classic four-arm structure (pictured to the right).^ Chromosomes Biology Concepts: Meiosis Meiosis is the process in which sex cells divide into four daughter cells, each with a haploid chromosomes (half the normal amount).

^ Robertsonian translocations involving the same chromosome often result in UPD. Isodisomy is the result of a non disjunction either in Meiosis II or post zygotic cell division (mitosis).
  • CHROMOSOME ABNORMALITIES: AUTOSOMES AND SEX CHROMOSOMES 19 January 2010 9:53 UTC www.carolguze.com [Source type: Academic]

^ These are examples of genetic imprinting a phenomenon that occurs during meiosis and which results in the male and female genetic contributions to the zygote not being the same.
  • CHROMOSOME ABNORMALITIES: AUTOSOMES AND SEX CHROMOSOMES 19 January 2010 9:53 UTC www.carolguze.com [Source type: Academic]

.Chromosomal recombination plays a vital role in genetic diversity.^ It is likely that similar sequence features may be important for duplication, genetic recombination and chromosomal rearrangement.
  • The DNA sequence of human chromosome 21 : Article : Nature 20 September 2009 15:32 UTC www.nature.com [Source type: Academic]

^ Crossing over Reciprocal exchange of corresponding segments between homologous chromosomes, resulting in recombination of genetic elements.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Genetic recombination The exchange of genetic material between homologous chromosomes in meiosis.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.If these structures are manipulated incorrectly, through processes known as chromosomal instability and translocation, the cell may undergo mitotic catastrophe and die, or it may aberrantly evade apoptosis leading to the progression of cancer.^ Chromosomes Biology Concepts: Meiosis Meiosis is the process in which sex cells divide into four daughter cells, each with a haploid chromosomes (half the normal amount).

^ These mutagenic and clastogenic effects in cultured cells are supported by positive effects in Drosophila germ cell tests that measure point mutations and chromosome breakage.
  • Fluoride's Mutagenicity (Genotoxicity) 19 January 2010 9:53 UTC www.fluoridealert.org [Source type: Academic]

^ While the findings described above support the possibility of nonrandom proximity between chromosomes in fibroblast nuclei, the observed cell-to-cell variability emphasizes the probabilistic nature of these patterns.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

In practice "chromosome" is a rather loosely defined term. In prokaryotes and viruses, the term genophore is more appropriate when no chromatin is present. .However, a large body of work uses the term chromosome regardless of chromatin content.^ The DNA content of individual human chromosomes [ 61 ] was used to estimate the number of 1-Mbp chromatin domains constituting a given model chromosome.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

.In prokaryotes DNA is usually arranged as a circle, which is tightly coiled in on itself, sometimes accompanied by one or more smaller, circular DNA molecules called plasmids.^ A plasmid is a circular, independent, self-replicating DNA molecule.

^ Molecular beacon A single-stranded DNA molecule with a fluorescent reporter group on one end and fluorescence quencher on the other.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ There is a white background and patches, more or less circular, of gold and black, with each patch coming from the clone of one cell with only black or gold turned on.
  • CHROMOSOME ABNORMALITIES: AUTOSOMES AND SEX CHROMOSOMES 19 January 2010 9:53 UTC www.carolguze.com [Source type: Academic]

.These small circular genomes are also found in mitochondria and chloroplasts, reflecting their bacterial origins.^ These small circular genomes are also found in mitochondria and chloroplasts, reflecting their bacterial origins.
  • Chromosome K-12 Experiments & Background Information 19 January 2010 9:53 UTC www.juliantrubin.com [Source type: Academic]
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]
  • What are chromosomes? - Yahoo! Answers 19 January 2010 9:53 UTC answers.yahoo.com [Source type: General]

^ These data and other information support the conclusion that the 13-paired species have a single common origin from a 14-paired genome comparable to that of D. scabra .
  • Hawaiian silversword alliance, UH Botany 19 January 2010 9:53 UTC www.botany.hawaii.edu [Source type: Academic]

^ The circular genomes of mitochondrial and chloroplast are a notable exception to the rule that eukaryotic chromosomes are linear.
  • Bacterial chromosome structure 19 January 2010 9:53 UTC www.sci.sdsu.edu [Source type: Academic]
  • Bacterial chromosome structure 11 September 2009 23:27 UTC www.sci.sdsu.edu [Source type: Academic]

.The simplest genophores are found in viruses: these DNA or RNA molecules are short linear or circular genophores that often lack structural proteins.^ RNA binding site A ribosomal region that binds mRNA. Multidimensional NMR Three- and four-dimensional NMR methods for the detailed characterization of protein structure.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Biomacromolecule A large biological molecule, such as DNA or protein.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Target A DNA, RNA, or protein that is involved in a disease process and is a suitable target for therapeutic compound development.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

Contents

History

Nucleus as the seat of heredity

The origin of this groundbreaking idea lies in a few sentences tucked away in Ernst Haeckel's Generelle Morphologie of 1866.[2] The evidence for this insight gradually accumulated until, after twenty or so years, two of the greatest in a line of great German scientists[citation needed] spelled out the concept. .August Weismann proposed that the germ line is separate from the soma, and that the cell nucleus is the repository of the hereditary material, which, he proposed, is arranged along the chromosomes in a linear manner.^ Germ cell Any cell of the germ line.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Germ line mutation A heritable genetic change in the germ line cells.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Germ line A cell line that gives rise to gametes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.Further, he proposed that at fertilisation a new combination of chromosomes (and their hereditary material) would be formed.^ Double in situ hybridization in combination with digital image analysis: A new approach to study interphase chromosome topography.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

.This was the explanation for the reduction division of meiosis (first described by van Beneden).^ Meiosis consists of two reductive divisions.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ This was the explanation for the reduction division of meiosis (first described by van Beneden).
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

^ Meiosis is the name used to describe the cell division that the egg and sperm go through when they are developing.

Chromosomes as vectors of heredity

In a series of experiments, Theodor Boveri gave the definitive demonstration that chromosomes are the vectors of heredity. His two principles were based upon the continuity of chromosomes and the individuality of chromosomes[citation needed].
It is the second of these principles that was so original[citation needed]. .Boveri was able to test the proposal put forward by Wilhelm Roux, that each chromosome carries a different genetic load, and showed that Roux was right.^ For a broad outline of the “Fitness test”, required to be passed to show a violation of the principle of Genetic Entropy, please see this following video and article: .
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

^ There are many people today who have different numbers of chromosomes due to fusion, and often you can't tell without genetic tests.
  • Human chromosome 2 - a creationist response 20 September 2009 15:32 UTC lukeplant.me.uk [Source type: Original source]

^ What is also interesting about the illustration is that the fusion that led to chromosome two was a telomeric fusion yet the illustration shows something entirely different.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

.Upon the rediscovery of Mendel, Boveri was able to point out the connection between the rules of inheritance and the behaviour of the chromosomes.^ Upon the rediscovery of Mendel, Boveri was able to point out the connection between the rules of inheritance and the behaviour of the chromosomes.
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

^ Explain how the behavior of these two pairs of homologous chromosomes during meiosis provides the physical basis for Mendel's two laws of inheritance.
  • AP Biology Outline for Genetics 11 September 2009 23:27 UTC apbio.biosci.uga.edu [Source type: Academic]

^ "Mutations in nuclear envelope components that link to the cytoskeleton show that the barrier to synapsis is imposed by the connection between the chromosomes and these nuclear envelope proteins."
  • UC Berkeley Press Release 19 January 2010 9:53 UTC www.berkeley.edu [Source type: Academic]

It is interesting to see that Boveri influenced two generations of American cytologists: Edmund Beecher Wilson, Walter Sutton and Theophilus Painter were all influenced by Boveri (Wilson and Painter actually worked with him).
In his famous textbook The Cell, Wilson linked Boveri and Sutton together by the Boveri-Sutton theory. Mayr remarks that the theory was hotly contested by some famous geneticists: William Bateson, Wilhelm Johannsen, Richard Goldschmidt and T.H. Morgan, all of a rather dogmatic turn-of-mind. Eventually complete proof came from chromosome maps in Morgan's own lab.[3]

Chromosomes in eukaryotes

.Eukaryotes (cells with nuclei such as those found in plants, yeast, and animals) possess multiple large linear chromosomes contained in the cell's nucleus.^ Eukaryote Any cell that contain a nucleus, including protists, animals, fungi, and plants.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ T1/2 cells containing   MeSH: Chromosomes, Human   [Hold mouse button down for author info.
  • WikiGenes - Chromosomes, Human 20 September 2009 15:32 UTC www.wikigenes.org [Source type: Academic]

^ While the findings described above support the possibility of nonrandom proximity between chromosomes in fibroblast nuclei, the observed cell-to-cell variability emphasizes the probabilistic nature of these patterns.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

.Each chromosome has one centromere, with one or two arms projecting from the centromere, although, under most circumstances, these arms are not visible as such.^ Together, these gene-poor regions comprise almost 10 Mb, which is one-third of chromosome 21.
  • The DNA sequence of human chromosome 21 : Article : Nature 20 September 2009 15:32 UTC www.nature.com [Source type: Academic]

^ From and evolutionary standpoint, the apes could have duplicated a chromosome, or one of theirs could have split into two, or two of the human chromosomes could have fused.
  • Human chromosome 2 - a creationist response 20 September 2009 15:32 UTC lukeplant.me.uk [Source type: Original source]

^ These results support evidence for nonrandom centromeric activity in humans and, more importantly, suggest a functional hierarchy in Robertsonian translocations with the chromosome 14 centromere most often active and the chromosome 15 centromere least often active.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

.In addition, most eukaryotes have a small circular mitochondrial genome, and some eukaryotes may have additional small circular or linear cytoplasmic chromosomes.^ Accordingly, the localization of the IGCs of smaller chromosomes towards the center of the rosette may simply reflect their small size.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ Genome map The linear arrangement of genes and markers within the chromosomes of a genome.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Mitochondrial RNA RNA transcribed from mitochondrial DNA. Mitochondrion (plural, mitochondria) A self-replicating organelle bound by two bilayer membranes that is found in the cytoplasm of eukaryotic cells.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.In the nuclear chromosomes of eukaryotes, the uncondensed DNA exists in a semi-ordered structure, where it is wrapped around histones (structural proteins), forming a composite material called chromatin.^ Chromatin The network of chromosomes, histones, and other proteins found in the eukaryotic nucleus during interphase.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Satellite DNA Highly repetitive, non-transcribed DNA regions in eukaryotic chromosomes that have a different sedimentatin coefficient than other nuclear DNA. Scaffold The molecular core common to all members of a combinatorial library; also proteins that are instrumental in the assembly of large 3-D structures.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Recently eukaryotic nuclear introns have been found to encode proteins.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

Chromatin

.Chromatin is the complex of DNA and protein found in the eukaryotic nucleus, which packages chromosomes.^ Chromatin The network of chromosomes, histones, and other proteins found in the eukaryotic nucleus during interphase.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ DNase footprinting A technique for locating the DNA sites bound by proteins that is based on the resistance of protein-DNA complexes to the action of nucleases.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Homo sapiens adaptor-related protein complex 1, beta 1 subunit (AP1B1), transcript variant 1 as transfection-ready DNA .
  • OriGene - Products by Chromosome 19 January 2010 9:53 UTC www.origene.com [Source type: Academic]

The structure of chromatin varies significantly between different stages of the cell cycle, according to the requirements of the DNA.

Interphase chromatin

During interphase (the period of the cell cycle where the cell is not dividing), two types of chromatin can be distinguished:
.
  • Euchromatin, which consists of DNA that is active, e.g., being expressed as protein.
  • Heterochromatin, which consists of mostly inactive DNA. It seems to serve structural purposes during the chromosomal stages.^ Unwinding protein A protein that binds single-stranded DNA, and stabilizes the unwinding of the helical structure.
    • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

    ^ Helix loop helix (Helix turn helix) A structure characteristic of DNA-binding proteins.
    • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

    ^ Chromatin The network of chromosomes, histones, and other proteins found in the eukaryotic nucleus during interphase.
    • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

    .Heterochromatin can be further distinguished into two types:
    • Constitutive heterochromatin, which is never expressed.^ Two types of chromatin can be distinguished: .

      ^ Heterochromatin can be further distinguished into two types: Constitutive heterochromatin , which is never expressed.
      • Chromosomes - Wikiversity 19 January 2010 9:53 UTC en.wikiversity.org [Source type: Academic]
      • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]
      • Chromosome 19 January 2010 9:53 UTC www.bio-medicine.org [Source type: Academic]

      ^ Heterochromatin can be subdivided into two subtypes: Constitutive heterochromatin , which is not expressed.
      • Chromosome - Flexikon 19 January 2010 9:53 UTC www.flexikon.com [Source type: Academic]

      It is located around the centromere and usually contains repetitive sequences.
    • Facultative heterochromatin, which is sometimes expressed.
.Individual chromosomes cannot be distinguished at this stage – they appear in the nucleus as a homogeneous tangled mix of DNA and protein.^ Histone Abundant small protein rich in arginine and lysine that associates with DNA and enables the packaging of DNA into chromosomes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Chromosome A structure that carries the heriditary information for an organism and consists of a long DNA molecule with associated proteins.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ The DNA content of individual human chromosomes [ 61 ] was used to estimate the number of 1-Mbp chromatin domains constituting a given model chromosome.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

Metaphase chromatin and division

Human chromosomes during metaphase.
.In the early stages of mitosis or meiosis (cell division), the chromatin strands become more and more condensed.^ Prophase : In the early stages of the mitosis, the chromatin strands condense increasingly.
  • Chromosome - Flexikon 19 January 2010 9:53 UTC www.flexikon.com [Source type: Academic]

^ In the early stages of mitosis, the chromatin strands become more and more condensed.

^ In the early stages of mitosis or meiosis (cell division), the chromatin strands become more and more condensed.
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

.They cease to function as accessible genetic material (transcription stops) and become a compact transportable form.^ They cease to function as accessible genetic material ( transcription stops) and become a compact transportable form.
  • Chromosomes - Wikiversity 19 January 2010 9:53 UTC en.wikiversity.org [Source type: Academic]
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]
  • Chromosome - Trust 19 January 2010 9:53 UTC enwiki-trust.cse.ucsc.edu [Source type: Academic]

^ They cease to function as accessible genetic material and become a compact transport form.

^ A general introduction to cell structure and function, molecular and organism genetics, animal development, form and function.
  • Browse: Keywords: Chromosome | OER Commons 19 January 2010 9:53 UTC www.oercommons.org [Source type: Academic]

.This compact form makes the individual chromosomes visible, and they form the classic four arm structure, a pair of sister chromatids attached to each other at the centromere.^ Kinetochore A pair of structures adjacent to the chromosomal centromere to which spindle microtubules attach.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Y Top X chromosome The sex chromosome that exists in paired form in females.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Centromere The chromosomal region to which spindle fibers attach when cells divide.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.The shorter arms are called p arms (from the French petit, small) and the longer arms are called q arms (q follows p in the Latin alphabet).^ Each chromosome has two arms, the shorter one called p arm (from the French petit, small) and the longer one q arm (q following p in the Latin alphabet).

^ The shorter arms are called p arms (from the French petit, small) and the longer arms are called q arms (q follows p in the Latin alphabet).

^ The uppermost end of each human chromosome (with the shorter, or p, arm) is called the "head end."
  • Lesson: Chromosome Fusion 19 January 2010 9:53 UTC www.indiana.edu [Source type: FILTERED WITH BAYES]

.This is the only natural context in which individual chromosomes are visible with an optical microscope.^ This is the only natural context in which individual chromosomes are visible with an optical microscope .

^ The chromosomes are visible under a microscope only in this spiral state.
  • Chromosome - Flexikon 19 January 2010 9:53 UTC www.flexikon.com [Source type: Academic]

^ This is the only natural context in which individual chromosomes are visible with an optical microscope.

.During divisions, long microtubules attach to the centromere and the two opposite ends of the cell.^ Centromere The chromosomal region to which spindle fibers attach when cells divide.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Gap phase G1 and G2 phases in cell division, during which there is no DNA synthesis.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Kinetochore A pair of structures adjacent to the chromosomal centromere to which spindle microtubules attach.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.The microtubules then pull the chromatids apart, so that each daughter cell inherits one set of chromatids.^ The microtubules then pull the chromatids apart, so that each daughter cell inherits one set of chromatids.

^ During mitosis, the microtubules pull apart both chromatids, so that each daughter cell contains one chromatid, i.e.
  • Chromosome - Flexikon 19 January 2010 9:53 UTC www.flexikon.com [Source type: Academic]

^ During mitosis, the microtubules pull the chromatids apart, so that each daughter cell inherits one set of chromatids.

.Once the cells have divided, the chromatids are uncoiled and can function again as chromatin.^ Once the cells have divided, the chromatids are uncoiled and can function again as chromatin.

^ During meiosis, a cell’s chromosomes are copied once, but the cell divides twice.
  • Inside the Cell: Chapter 4: Cellular Reproduction: Multiplication by Division - National Institute of General Medical Sciences 19 January 2010 9:53 UTC publications.nigms.nih.gov [Source type: FILTERED WITH BAYES]

^ During mitosis, the centromere that is shared by the sister chromatids must divide so that the chromatids can migrate to opposite poles of the cell.
  • DNA Structure, Replication and Eukaryotic Chromatin Structure 19 January 2010 9:53 UTC www.ndsu.edu [Source type: Academic]

.In spite of their appearance, chromosomes are structurally highly condensed, which enables these giant DNA structures to be contained within a cell nucleus (Fig.^ Chromatophore Pigment-containing cells within the dermis of fish and amphibians.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ T1/2 cells containing   MeSH: Chromosomes, Human   [Hold mouse button down for author info.
  • WikiGenes - Chromosomes, Human 20 September 2009 15:32 UTC www.wikigenes.org [Source type: Academic]

^ Find this article online Cremer T, Küpper K, Dietzel S, Fakan S (2004) Higher order chromatin architecture in the cell nucleus: On the way from structure to function.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

2).
.The self-assembled microtubules form the spindle, which attaches to chromosomes at specialized structures called kinetochores, one of which is present on each sister chromatid.^ Kinetochore A pair of structures adjacent to the chromosomal centromere to which spindle microtubules attach.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Centromere The chromosomal region to which spindle fibers attach when cells divide.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Anaphase The stage of nuclear division when chromatids (homologous chromosomes) move to the poles of the mitotic spindle.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.A special DNA base sequence in the region of the kinetochores provides, along with special proteins, longer-lasting attachment in this region.^ A special DNA base sequence in the region of the kinetochores provides, along with special proteins, longer-lasting attachment in this region.

^ This tree is based on DNA sequence comparisons among the species in this family.
  • NOVA Online | Teachers | Classroom Activity | Judgment Day: Intelligent Design on Trial | PBS 20 September 2009 15:32 UTC www.pbs.org [Source type: FILTERED WITH BAYES]

^ Chromosomes contain a line of different genes, a spindle attachment at some point along their length, and regions of heterochromatin, which stains strongly with basic dyes.
  • chromosome Facts, information, pictures | Encyclopedia.com articles about chromosome 19 January 2010 9:53 UTC www.encyclopedia.com [Source type: Academic]

Chromosomes in prokaryotes

The prokaryotes – bacteria and archaea – typically have a single circular chromosome, but many variations do exist.[4] .Most bacteria have a single circular chromosome that can range in size from only 160,000 base pairs in the endosymbiotic bacterium Candidatus Carsonella ruddii,[5] to 12,200,000 base pairs in the soil-dwelling bacterium Sorangium cellulosum.^ Kilobase (kb) A unit of DNA length; 1 kb is equal to 1,000 base pairs.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Chromosome-size-correlated radial CT arrangements are most obvious in 2D nuclear projections (see Figures 2 and S2).
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ Single nucleotide polymorphism (SNP) Scattered single-base pair variations within the genetic code of the individuals of a population.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

[6] .Spirochaetes of the genus Borrelia are a notable exception to this arrangement, with bacteria such as Borrelia burgdorferi, the cause of Lyme disease, containing a single linear chromosome.^ Genome map The linear arrangement of genes and markers within the chromosomes of a genome.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

[7]

Structure in sequences

.Prokaryotic chromosomes have less sequence-based structure than eukaryotes.^ We have one less chromosome than apes.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

^ Operon A prokaryotic DNA region that coordinates the regulatory and structural sequences for a gene or set of related genes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ It’s predicted because we have one less chromosome than apes, when we are supposed to be related to apes.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

.Bacteria typically have a single point (the origin of replication) from which replication starts, whereas some archaea contain multiple replication origins.^ At some point, according to evolution, atoms bumping together started to "live."
  • Human chromosome 2 - a creationist response 20 September 2009 15:32 UTC lukeplant.me.uk [Source type: Original source]

^ Minichromosome A plasmid that contains a chromosomal origin of replication.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

[8] .The genes in prokaryotes are often organized in operons, and do not usually contain introns, unlike eukaryotes.^ Operon A prokaryotic DNA region that coordinates the regulatory and structural sequences for a gene or set of related genes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

DNA packaging

Prokaryotes do not possess nuclei. .Instead, their DNA is organized into a structure called the nucleoid.^ Denature To cause a protein to fold into a structure other than the native 3-D conformation; to convert double-stranded DNA to single-stranded DNA. Dendrimer A branching polymer.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Reverse gyrase An enzyme with a DNA helicase and DNA topoisomerase domains that induces positive supercoiling into DNA. Reverse micelle The structure formed by amphipathic molecules in a nonpolar solvent.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

[9] .The nucleoid is a distinct structure and occupies a defined region of the bacterial cell.^ The nucleoid is a distinct structure and occupies a defined region of the bacterial cell.
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

^ Telomeres were initially recognized as distinct structures because broken chromosomes were highly unstable in eukaryotic cells, implying that specific sequences are required at normal chromosomal termini.
  • Chromosomes and Chromatin -- The Cell -- NCBI Bookshelf 19 January 2010 9:53 UTC www.ncbi.nlm.nih.gov [Source type: Academic]

^ Domain A compact structural region within a protein with a distinct function.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.This structure is, however, dynamic and is maintained and remodeled by the actions of a range of histone-like proteins, which associate with the bacterial chromosome.^ Chromatin The network of chromosomes, histones, and other proteins found in the eukaryotic nucleus during interphase.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Computational chemistry Computer-based modeling and prediction of the structure of chemical compounds most likely to bind a protein drug target.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Histone Abundant small protein rich in arginine and lysine that associates with DNA and enables the packaging of DNA into chromosomes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

[10] .In archaea, the DNA in chromosomes is even more organized, with the DNA packaged within structures similar to eukaryotic nucleosomes.^ Archaebacteria, however, do contain histones that package their DNAs in structures similar to eukaryotic chromatin.
  • Chromosomes and Chromatin -- The Cell -- NCBI Bookshelf 19 January 2010 9:53 UTC www.ncbi.nlm.nih.gov [Source type: Academic]

^ Telomeres (from the Greek telos which means end) are structures located at the end of eukaryotic chromosomes (linear DNA).
  • Tag: Chromosome - Explore content tagged Chromosome on eHow.com 19 January 2010 9:53 UTC www.ehow.com [Source type: Academic]

^ In spite of their appearance, chromosomes are structurally highly condensed which enables these giant DNA structures to be contained within a cell nucleus (Fig.

[11][12]
.Bacterial chromosomes tend to be tethered to the plasma membrane of the bacteria.^ Bacterial chromosomes tend to be tethered to the plasma membrane of the bacteria.
  • Chromosomes - Wikiversity 19 January 2010 9:53 UTC en.wikiversity.org [Source type: Academic]
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]
  • Chromosome - Trust 19 January 2010 9:53 UTC enwiki-trust.cse.ucsc.edu [Source type: Academic]

^ When linear, bacterial chromosomes tend to be tethered to the plasma membrane of the bacteria.

^ Bacterial DNA also exists as plasmids , essentially miniature chromosomes, which are small circular pieces of DNA that are readily transmitted between bacteria.
  • Chromosomes - Wikiversity 19 January 2010 9:53 UTC en.wikiversity.org [Source type: Academic]

.In molecular biology application, this allows for its isolation from plasmid DNA by centrifugation of lysed bacteria and pelleting of the membranes (and the attached DNA).^ In molecular biology application, this allows for its isolation from plasmid DNA by centrifugation of lysed bacteria and pelleting of the membranes (and the attached DNA).
  • Chromosomes - Wikiversity 19 January 2010 9:53 UTC en.wikiversity.org [Source type: Academic]
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

^ In molecular biology application, this allows for its isolation from plasmid DNA by centrifugation of lysed bacteria and pelleting of membranes (and the attached DNA).

^ As we know from molecular biology's "central dogma," the order of nucleotides in a gene's DNA sequence determine the order of amino acids in a protein sequence.
  • Gene Guide 20 September 2009 15:32 UTC www.ornl.gov [Source type: Academic]

.Prokaryotic chromosomes and plasmids are, like eukaryotic DNA, generally supercoiled.^ Subclone A DNA clone generated by transferring a cloned DNA fragment from one plasmid to another.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.The DNA must first be released into its relaxed state for access for transcription, regulation, and replication.^ In its relaxed state, the DNA can be accessed for transcription, regulation, and replication.

^ The DNA must first be released into its relaxed state for access for transcription , regulation, and replication .

^ Because each new cell requires a complete set of DNA molecules, the DNA molecules in the original cell must reproduce (replicate) themselves during cell division.
  • Chromosomes and Genes: Genetics: Merck Manual Home Edition 19 January 2010 9:53 UTC www.merck.com [Source type: Academic]

Fig. 2: The major structures in DNA compaction; DNA, the nucleosome, the 10nm "beads-on-a-string" fibre, the 30nm fibre and the metaphase chromosome.

Number of chromosomes in various organisms

Eukaryotes

.These tables give the total number of chromosomes (including sex chromosomes) in a cell nucleus.^ While the findings described above support the possibility of nonrandom proximity between chromosomes in fibroblast nuclei, the observed cell-to-cell variability emphasizes the probabilistic nature of these patterns.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ Diploid A cell or nucleus that has two sets of homologous chromosomes, one derived from each parent.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Eukaryote Any cell that contain a nucleus, including protists, animals, fungi, and plants.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.For example, human cells are diploid and have 22 different types of autosome, each present as two copies, and two sex chromosomes.^ The human genome consists of 22 pairs of autosomes, and one pair of sex chromosomes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Autosome A chromosome not involved in sex determination.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ The DNA sequence of human chromosome 22.
  • The DNA sequence of human chromosome 21 : Article : Nature 20 September 2009 15:32 UTC www.nature.com [Source type: Academic]

This gives 46 chromosomes in total. .Other organisms have more than two copies of their chromosomes, such as bread wheat, which is hexaploid and has six copies of seven different chromosomes – 42 chromosomes in total.^ For example, two different regions in the 21p contig (42–84 kb; 239–263 kb) are duplicated in 22q (1043–1067 kb; 1539–1564 kb).
  • The DNA sequence of human chromosome 21 : Article : Nature 20 September 2009 15:32 UTC www.nature.com [Source type: Academic]

^ The repeat units share more than 91% identity with each other.
  • The DNA sequence of human chromosome 21 : Article : Nature 20 September 2009 15:32 UTC www.nature.com [Source type: Academic]

^ Chimera An organism combining tissues derived from two or more genotypes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

Chromosome numbers in some plants
Plant Species #
Arabidopsis thaliana (diploid)[13] 10
Rye (diploid)[14] 14
Maize (diploid or palaeotetraploid)[15] 20
Einkorn wheat (diploid)[16] 14
Durum wheat (tetraploid)[16] 28
Bread wheat (hexaploid)[16] 42
Cultivated tobacco (tetraploid)[17] 48
Adder's Tongue Fern (diploid)[18] approx 1,400
Chromosome numbers (2n) in some animals
Species # Species #
Common fruit fly 8 Guinea Pig[19] 64
Guppy (poecilia reticulata)[20] 23 Garden snail[21] 54
Earthworm (Octodrilus complanatus)[22] 36 Tibetan fox 36
Domestic cat[23] 38 Domestic pig 38
Laboratory mouse[24][25] 40 Laboratory rat[25] 42
Rabbit (Oryctolagus cuniculus)[26] 44 Syrian hamster[24] 44
Hares[27][28] 48 Human[29] 46
Gorillas, Chimpanzees[29] 48 Domestic sheep 54
Elephants[30] 56 Cow 60
Donkey 62 Horse 64
Dog[31] 78 Kingfisher[32] 132
Goldfish[33] 100-104 Silkworm[34] 56
Chromosome numbers in other organisms
Species Large
Chromosomes
Intermediate
Chromosomes
Microchromosomes
Trypanosoma brucei 11 6 ~100
Domestic Pigeon (Columba livia domestics)[35] 18 - 59-63
Chicken[36] 8 2 sex chromosomes 60
.Normal members of a particular eukaryotic species all have the same number of nuclear chromosomes (see the table).^ The handout also includes the number of chromosomes for each species.
  • NOVA Online | Teachers | Classroom Activity | Judgment Day: Intelligent Design on Trial | PBS 20 September 2009 15:32 UTC www.pbs.org [Source type: FILTERED WITH BAYES]

^ Normal members of a particular eukaryotic species all have the same number of nuclear chromosomes (see the table).

^ Shall define a convention for the order of different Chromosomes located on the same Individual and appends all such Chromosomes to the Inividual.

.Other eukaryotic chromosomes, i.e., mitochondrial and plasmid-like small chromosomes, are much more variable in number, and there may be thousands of copies per cell.^ The number of chromosomes in the egg or sperm is different from that in other body cells.
  • Unique - The Rare Chromosome Disorder Support Group - www.RareChromo.org 11 September 2009 23:27 UTC www.rarechromo.org [Source type: FILTERED WITH BAYES]

^ Subsequent generations would have even more chromosomes per cell.
  • Inside the Cell: Chapter 4: Cellular Reproduction: Multiplication by Division - National Institute of General Medical Sciences 19 January 2010 9:53 UTC publications.nigms.nih.gov [Source type: FILTERED WITH BAYES]

^ Other chromosome numbers .
  • 7 Genetic Research and Chromosome Number 19 January 2010 9:53 UTC www.nal.usda.gov [Source type: FILTERED WITH BAYES]

The 23 human chromosome territories during prometaphase in fibroblast cells.
.Asexually reproducing species have one set of chromosomes, which are the same in all body cells.^ All I am saying is that when one looks at the “evidence” for common ancestry it is very apparent that the same “evidence” can be used to support common design and/ or convergence.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

^ My point is that ID and evolution were looking at the same set of data at any one point, and evolution could have retroactively predicted any number of things, because that’s what’s happened in evolution.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

^ Allozyme, alloenzyme One of the different forms of an enzyme found in individuals of the same species, due to the presence of multiple alleles in the population.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

However, asexual species can be either haploid or diploid.
.Sexually reproducing species have somatic cells (body cells), which are diploid [2n] having two sets of chromosomes, one from the mother and one from the father.^ Haploid cells have one complete set of chromosomes.

^ Replication: Cells reproduce by splitting in two.
  • Chromosomes and Genes: Genetics: Merck Manual Home Edition 19 January 2010 9:53 UTC www.merck.com [Source type: Academic]

^ Are the two sets of daughter chromosomes identical to those in the parent cell?

.Gametes, reproductive cells, are haploid [n]: They have one set of chromosomes.^ Gamete Mature reproductive cell with a haploid set of chromosomes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ After all, if they could have come up with any old thing, evidence bedamned, why did they settle on the one possibility that is consistent with known chromosome behavior?
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

^ They knew to look for a fused chromosome because, according to the hypothesis of common descent, we were short one.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

.Gametes are produced by meiosis of a diploid germ line cell.^ Germ cell Any cell of the germ line.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Germ line A cell line that gives rise to gametes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Germ line mutation A heritable genetic change in the germ line cells.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.During meiosis, the matching chromosomes of father and mother can exchange small parts of themselves (crossover), and thus create new chromosomes that are not inherited solely from either parent.^ Pairing of X and Y chromosomes during meiosis .
  • Chapter03x 11 September 2009 23:27 UTC www.cns.pdx.edu [Source type: Academic]

^ During meiosis, the matching chromosomes of father and mother can exchange small parts of themselves ( crossover ), and thus create new chromosomes that are not inherited solely from either parent.
  • Chromosomes - Wikiversity 19 January 2010 9:53 UTC en.wikiversity.org [Source type: Academic]
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

^ There are 23 chromosomes from the mother and a "Y" chromosome from a father.
  • Chromosomes, Somatids, and the Blood of Christ | Ark of Covenant 19 January 2010 9:53 UTC anchorstone.com [Source type: Original source]

When a male and a female gamete merge (fertilization), a new diploid organism is formed.
.Some animal and plant species are polyploid [Xn]: They have more than two sets of homologous chromosomes.^ However, we cannot firmly exclude at present the possibility that some homologous chromosome pairs occupy nonrandom “orbital” positions with regard to each other.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ Monosome A chromosome in a diploid set with no homolog.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ For example, the cells of some salamanders may contain 40 times more DNA than those of humans.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

Plants important in agriculture such as tobacco or wheat are often polyploid, compared to their ancestral species. .Wheat has a haploid number of seven chromosomes, still seen in some cultivars as well as the wild progenitors.^ Haploid Genetic material consisting of a single chromosome set (half of the diploid number).
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.The more-common pasta and bread wheats are polyploid, having 28 (tetraploid) and 42 (hexaploid) chromosomes, compared to the 14 (diploid) chromosomes in the wild wheat.^ We also compared the radial voxel distributions of the CTs of HSAs 1 and 20 as an example of a large and a small chromosome having similar average gene densities ( Figure 6 C and 6 F).
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ D projections of the IGCs determined for all chromosome types (1–22, X, and Y) present in 28 prometaphase rosettes of male diploid human fibroblasts (compare to Figure S2 ).
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

[37]

Prokaryotes

.Prokaryote species generally have one copy of each major chromosome, but most cells can easily survive with multiple copies.^ Do most of our cells have one or two copies of each chromosome?
  • Inside the Cell: Chapter 4: Cellular Reproduction: Multiplication by Division - National Institute of General Medical Sciences 19 January 2010 9:53 UTC publications.nigms.nih.gov [Source type: FILTERED WITH BAYES]

^ Prokaryote species generally have one copy of each major chromosome, but most cells can easily survive with multiple copies.
  • Chromosomes - Wikiversity 19 January 2010 9:53 UTC en.wikiversity.org [Source type: Academic]
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]
  • Chromosome - Trust 19 January 2010 9:53 UTC enwiki-trust.cse.ucsc.edu [Source type: Academic]

^ For example, Buchnera , a symbiont of aphids has multiple copies of its chromosome, ranging from 10–400 copies per cell.
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

[38] .For example, Buchnera, a symbiont of aphids has multiple copies of its chromosome, ranging from 10–400 copies per cell.^ Y Chromosome Down Syndrome Information: Causes of Down Syndrome Down syndrome is a chromosomal disorder in which there is an extra copy of chromosome 21 in the cells of the developing fetus.

^ Degrading Down Syndrome Information: Frequently Asked Questions (FAQ) Down syndrome is a chromosomal disorder in which there is an extra copy of chromosome 21 in the cells of the developing fetus.

^ Myelin Down Syndrome Information: Diagnosis of Down Syndrome Down syndrome is a chromosomal disorder in which there is an extra copy of chromosome 21 in the cells of the developing fetus.

[39] .However, in some large bacteria, such as Epulopiscium fishelsoni up to 100,000 copies of the chromosome can be present.^ However, we cannot firmly exclude at present the possibility that some homologous chromosome pairs occupy nonrandom “orbital” positions with regard to each other.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ Bacterial artificial chromosome (BAC) A vector capable of replication in bacteria that is used to clone 100 to 300 kb DNA fragments into E. coli cells.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

[40] .Plasmids and plasmid-like small chromosomes are, as in eukaryotes, very variable in copy number.^ Consistent with this variability 3D CT–CN–CT angles ( Figure S9 ) and 3D PC–CR–PC angles ( Figure S10 ) ranged from very small to large angles near 180°.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ The volume of a given iS was proportional to the DNA content of its natural chromosome counterpart, while its radius was very small compared with the half-axes of the ellipsoid.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ As the result of an extra copy of chromosome 21 that the developing fetus possesses, the child with Down syndrome has physical, medical, and cognitive disorders which vary in severity from case to case.

.The number of plasmids in the cell is almost entirely determined by the rate of division of the plasmid – fast division causes high copy number, and vice versa.^ Immortalization The generation of cells that undergo an infinite number of division cycles.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Syndrome Down Syndrome Information: Causes of Down Syndrome Down syndrome is a chromosomal disorder in which there is an extra copy of chromosome 21 in the cells of the developing fetus.

^ Chromosome Down Syndrome Down syndrome is a genetic disease caused by three major factors, genetics, chromosome formation and cell division.

Karyotype

Figure 3: Karyogram of a human male
.In general, the karyotype is the characteristic chromosome complement of a eukaryote species.^ In general, the karyotype is the characteristic chromosome complement of a eukaryote species .
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

^ A diagram of the chromosome complement of a species, showing banding patterns, that is often used to compare karyotypes of different species.
  • NOVA Online | Teachers | Classroom Activity | Judgment Day: Intelligent Design on Trial | PBS 20 September 2009 15:32 UTC www.pbs.org [Source type: FILTERED WITH BAYES]

^ The observation of karyotypic uniformity in most species has led to the widespread belief that selection limits chromosomal change.
  • The Rise of Human Chromosome 2: The Fertility Problem - The Panda's Thumb 20 September 2009 15:32 UTC pandasthumb.org [Source type: FILTERED WITH BAYES]

[41] .The preparation and study of karyotypes is part of cytogenetics.^ The preparation and study of karyotypes is part of cytogenetics .
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

.Although the replication and transcription of DNA is highly standardized in eukaryotes, the same cannot be said for their karyotypes, which are often highly variable.^ Homo sapiens chromosome 22 open reading frame 33 (C22orf33), transcript variant 2 as transfection-ready DNA .
  • OriGene - Products by Chromosome 19 January 2010 9:53 UTC www.origene.com [Source type: Academic]

^ Homo sapiens peroxisome proliferator-activated receptor alpha (PPARA), transcript variant 5 as transfection-ready DNA .
  • OriGene - Products by Chromosome 19 January 2010 9:53 UTC www.origene.com [Source type: Academic]

^ Homo sapiens cat eye syndrome chromosome region candidate 6 (CECR6) transcript variant 2 as transfection-ready DNA .
  • OriGene - Products by Chromosome 19 January 2010 9:53 UTC www.origene.com [Source type: Academic]

.There may be variation between species in chromosome number and in detailed organization.^ Number of chromosomes in various organisms .

^ There may be variation between species in chromosome number and in detailed organization.
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

^ The handout also includes the number of chromosomes for each species.
  • NOVA Online | Teachers | Classroom Activity | Judgment Day: Intelligent Design on Trial | PBS 20 September 2009 15:32 UTC www.pbs.org [Source type: FILTERED WITH BAYES]

.In some cases, there is significant variation within species.^ SNPs determine ways that subpopulations within a species differ and provide information about variations of protein expression.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Comparative genomics makes possible the application of information gained from a simple genome to a more complex genome, and is the basis for the understanding of genetic variation within a species.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

Often there is:
1. variation between the two sexes
2. variation between the germ-line and soma (between gametes and the rest of the body)
3. variation between members of a population, due to balanced genetic polymorphism
4. geographical variation between races
5. mosaics or otherwise abnormal individuals.
Also, variation in karyotype may occur during development from the fertilised egg.
.The technique of determining the karyotype is usually called karyotyping.^ The technique of determining the karyotype is usually called karyotyping .
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

Cells can be locked part-way through division (in metaphase) in vitro (in a reaction vial) with colchicine. .These cells are then stained, photographed, and arranged into a karyogram, with the set of chromosomes arranged, autosomes in order of length, and sex chromosomes (here X/Y) at the end: Fig.^ Autosome A chromosome not involved in sex determination.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ While the findings described above support the possibility of nonrandom proximity between chromosomes in fibroblast nuclei, the observed cell-to-cell variability emphasizes the probabilistic nature of these patterns.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ The human genome consists of 22 pairs of autosomes, and one pair of sex chromosomes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

3.
.Like many sexually reproducing species, humans have special gonosomes (sex chromosomes, in contrast to autosomes).^ Chromosome 21 is the smallest human autosome.
  • The DNA sequence of human chromosome 21 : Article : Nature 20 September 2009 15:32 UTC www.nature.com [Source type: Academic]

^ Autosome A chromosome not involved in sex determination.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ The human genome consists of 22 pairs of autosomes, and one pair of sex chromosomes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.These are XX in females and XY in males.^ These are XX in females and XY in males, and can be seen in the karyotype, Fig.
  • Chromosomes - Wikiversity 19 January 2010 9:53 UTC en.wikiversity.org [Source type: Academic]

^ These are XX in females and XY in males.
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

^ These are examples of genetic imprinting a phenomenon that occurs during meiosis and which results in the male and female genetic contributions to the zygote not being the same.
  • CHROMOSOME ABNORMALITIES: AUTOSOMES AND SEX CHROMOSOMES 19 January 2010 9:53 UTC www.carolguze.com [Source type: Academic]

Historical note

Investigation into the human karyotype took many years to settle the most basic question. .How many chromosomes does a normal diploid human cell contain?^ Chromosomes Biology Concepts: Meiosis Meiosis is the process in which sex cells divide into four daughter cells, each with a haploid chromosomes (half the normal amount).

^ Chromosomes exhibit preferential positioning in nuclei of quiescent human cells.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ Non-random radial higher-order chromatin arrangements in nuclei of diploid human cells.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

.In 1912, Hans von Winiwarter reported 47 chromosomes in spermatogonia and 48 in oogonia, concluding an XX/XO sex determination mechanism.^ Autosome A chromosome not involved in sex determination.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Sex determination The genetic specification of the sex of an individual by the genes of the X and Y chromosomes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

[42] .Painter in 1922 was not certain whether the diploid number of man is 46 or 48, at first favouring 46.[43] He revised his opinion later from 46 to 48, and he correctly insisted on man's having an XX/XY system.^ Briefly, starting configurations representing a statistical chromatid distribution in male diploid human fibroblasts (46, XY) at late anaphase/telophase were established as follows.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

[44]
New techniques were needed to definitively solve the problem:
1. Using cells in culture
2. Pretreating cells in a hypotonic solution, which swells them and spreads the chromosomes
3. Arresting mitosis in metaphase by a solution of colchicine
4. Squashing the preparation on the slide forcing the chromosomes into a single plane
5. Cutting up a photomicrograph and arranging the result into an indisputable karyogram.
.It took until the mid-1950s for it to become generally accepted that the human karyotype include only 46 chromosomes.^ Until one centromere becomes inactivated the new chromosome will have two active centromeres (dicentric).
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

^ Chromosome banding and M-FISH analyses performed after the second passage (1:2 split) showed a normal male karyotype (46, XY).
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ The total volume of the 46 iSs (representing the 46 chromosomes of the diploid human complement) comprised 22% of the total volume of the ellipsoidal model nucleus.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

Considering the techniques of Winiwarter and Painter, their results were quite remarkable.[45][46] .Chimpanzees (the closest living relatives to modern humans) have 48 chromosomes.^ That is the original humans had 48 chromosomes.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

^ All these genetic elements can ONLY be inherited, and we share them with chimps, our closest living relatives.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

^ DNA lineage belonging to an anatomically modern human, because this lineage is not found in living Australians.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

Chromosomal aberrations

The three major single chromosome mutations; deletion (1), duplication (2) and inversion (3).
The two major two-chromosome mutations; insertion (1) and translocation (2).
In Down syndrome, there are three copies of chromosome 21
.Chromosomal aberrations are disruptions in the normal chromosomal content of a cell, and are a major cause of genetic conditions in humans, such as Down syndrome.^ Chromosomes exhibit preferential positioning in nuclei of quiescent human cells.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ Figure 3 displays the positive correlation obtained in quiescent human fibroblasts for the mean normalized radial CN–CT distances and the DNA content of the chromosomes.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ Find this article online Koss LG (1998) Characteristics of chromosomes in polarized normal human bronchial cells provide a blueprint for nuclear organization.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

.Some chromosome abnormalities do not cause disease in carriers, such as translocations, or chromosomal inversions, although they may lead to a higher chance of birthing a child with a chromosome disorder.^ Chromosome Down Syndrome Down syndrome is a genetic disease caused by three major factors, genetics, chromosome formation and cell division.

^ To some extent the spindle may reinforce a size-correlated radial arrangement of chromosomes (see [ 12 ] and references therein).
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ Y Chromosome Down Syndrome Information: Causes of Down Syndrome Down syndrome is a chromosomal disorder in which there is an extra copy of chromosome 21 in the cells of the developing fetus.

.Abnormal numbers of chromosomes or chromosome sets, aneuploidy, may be lethal or give rise to genetic disorders.^ Abnormal numbers of chromosomes or chromosome sets, aneuploidy , may be lethal or give rise to genetic disorders.
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

^ Abnormality of chromosome number or structure.
  • IUPAC Glossary of Terms Used in Toxicology – Terms Starting with C 19 January 2010 9:53 UTC sis.nlm.nih.gov [Source type: Academic]

^ CHROMOSOME ABNORMALITIES OF NUMBER It is estimated that 10% of sperm and 50% of eggs contain abnormal chromosomes (both numerical and structural).
  • CHROMOSOME ABNORMALITIES: AUTOSOMES AND SEX CHROMOSOMES 19 January 2010 9:53 UTC www.carolguze.com [Source type: Academic]

.Genetic counseling is offered for families that may carry a chromosome rearrangement.^ Genetic counseling is offered for families that may carry a chromosome rearrangement.
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

^ Therefore, the diagnosis of the present invention may be carried out by any means which is capable of detecting change of chromosome regions, aberration of which is intended to be detected.
  • METHOD OF CANCER DIAGNOSIS BASED ON THE DETECTION OF CHROMOSOME ABNORMALITY - Patent EP1092783 20 September 2009 15:32 UTC www.freepatentsonline.com [Source type: Academic]

^ Y Chromosome A Look at Genetic Genealogy DNA analysis can help family historians break through brick walls and uncover information on genetic disorders and disease.

.The gain or loss of DNA from chromosomes can lead to a variety of genetic disorders.^ Chromosome alterations in breast carcinomas: frequent involvement of DNA losses including chromosomes 4q and 21q.
  • The DNA sequence of human chromosome 21 : Article : Nature 20 September 2009 15:32 UTC www.nature.com [Source type: Academic]

^ Several anonymous loci for monogenic disorders and predispositions for common complex disorders have also been mapped to this chromosome, and loss of heterozygosity has been observed in regions associated with solid tumours.
  • The DNA sequence of human chromosome 21 : Article : Nature 20 September 2009 15:32 UTC www.nature.com [Source type: Academic]

^ Deletion The loss of genetic material from a gene or a chromosome.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

Human examples include:
.
  • Cri du chat, which is caused by the deletion of part of the short arm of chromosome 5. "Cri du chat" means "cry of the cat" in French, and the condition was so-named because affected babies make high-pitched cries that sound like those of a cat.^ Presence Klinefelter Syndrome--When Your Baby Boy Has a Chromosome Abnormality This syndrome affects only males and is caused by the wrong number of chromosomes upsetting the natural balance of the body.

    ^ They knew to look for a fused chromosome because, according to the hypothesis of common descent, we were short one.
    • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

    ^ The acrocentric chromosomes (13–15, 21, and 22) carry nucleolar organizer regions (NORs) on their short arms, and active NORs are associated with the nucleoli.
    • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

    .Affected individuals have wide-set eyes, a small head and jaw, and are moderately to severe mental health issues and very short.
  • Down syndrome, usually is caused by an extra copy of chromosome 21 (trisomy 21).^ Down syndrome is a chromosomal disorder in which there is an extra copy of chromosome 21 in the cells of the developing fetus.

    ^ Syndrome Down Syndrome Information: Causes of Down Syndrome Down syndrome is a chromosomal disorder in which there is an extra copy of chromosome 21 in the cells of the developing fetus.

    ^ Down syndrome is a chromosomal disorder.

    Characteristics include decreased muscle tone, stockier build, asymmetrical skull, slanting eyes and mild to moderate mental retardation.[47]
  • .
  • Edwards syndrome, which is the second-most-common trisomy; Down syndrome is the most common.^ The most common question I am asked is “What is Angelman Syndrome?” This article is an attempt to give others a general overview of the disorder.

    ^ On the other hand, Down syndrome patients have a markedly increased risk of childhood leukaemia 19 , and trisomy of chromosome 21 in blast cells is one of the most common chromosomal aneuploidies seen in childhood leukaemias 40 .
    • The DNA sequence of human chromosome 21 : Article : Nature 20 September 2009 15:32 UTC www.nature.com [Source type: Academic]

    ^ An extra copy of chromosome 21 causes Down syndrome, the most frequent genetic cause of significant mental retardation, which affects up to 1 in 700 live births.
    • The DNA sequence of human chromosome 21 : Article : Nature 20 September 2009 15:32 UTC www.nature.com [Source type: Academic]

    It is a trisomy of chromosome 18. Symptoms include mental and motor retardation and numerous congenital anomalies causing serious health problems. .Ninety percent die in infancy; however, those that live past their first birthday usually are quite healthy thereafter.^ A non-living virus which depends on those human cells to replicate in the first place.
    • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

    .They have a characteristic clenched hands and overlapping fingers.
  • Idic15, abbreviation for Isodicentric 15 on chromosome 15; also called the following names due to various researches, but they all mean the same; IDIC(15), Inverted duplication 15, extra Marker, Inv dup 15, partial tetrasomy 15
  • Jacobsen syndrome, also called the terminal 11q deletion disorder.^ The malaria parasite, due to its comparatively enormous population size, has in 1 year more mutation/duplication/selection events than all mammal lineages have had in the entire +100 million years they have been in the fossil record.
    • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

    ^ After all, if they could have come up with any old thing, evidence bedamned, why did they settle on the one possibility that is consistent with known chromosome behavior?
    • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

    ^ When all chromosomes are capped by teleomeres with a centromere in the middle, and our chromosome #2 is capped by telomeres, followed by two centromeres farther in, and two telomeres in the middle?
    • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

    [48] This is a very rare disorder. Those affected have normal intelligence or mild mental retardation, with poor expressive language skills. .Most have a bleeding disorder called Paris-Trousseau syndrome.
  • Klinefelter's syndrome (XXY).^ Embryo Recognizing Angelman Syndrome: A Rare Disorder My daughter Noel was born with a rare neuro-genetic disorder called Angelman Syndrome.

    ^ The most common question I am asked is “What is Angelman Syndrome?” This article is an attempt to give others a general overview of the disorder.

    ^ Chromosome Rett's Syndrome: A Rare Genetic Mutation that Occurs in Women Rett's Syndrome is a genetic disorder that occurs on the X chromosome that most often occurs in females.

    Men with Klinefelter syndrome are usually sterile, and tend to have longer arms and legs and to be taller than their peers. .Boys with the syndrome are often shy and quiet, and have a higher incidence of speech delay and dyslexia.^ Speech Delays Finding Information Online About Turner's Syndrome Turner's Syndrome is an inherited, chromosome disorder that only affects females.

    .During puberty, without testosterone treatment, some of them may develop gynecomastia.
  • Patau Syndrome, also called D-Syndrome or trisomy-13. Symptoms are somewhat similar to those of trisomy-18, but they do not have the characteristic hand shape.
  • Small supernumerary marker chromosome.^ Y Chromosome Down Syndrome Information: Causes of Down Syndrome Down syndrome is a chromosomal disorder in which there is an extra copy of chromosome 21 in the cells of the developing fetus.

    ^ Data from transgenic mice indicate that only a subset of the genes on chromosome 21 may be involved in the phenotypes of Down syndrome 20 .
    • The DNA sequence of human chromosome 21 : Article : Nature 20 September 2009 15:32 UTC www.nature.com [Source type: Academic]

    ^ Degrading Down Syndrome Information: Frequently Asked Questions (FAQ) Down syndrome is a chromosomal disorder in which there is an extra copy of chromosome 21 in the cells of the developing fetus.

    .This means there is an extra, abnormal chromosome.^ Y Chromosome Down Syndrome Information: Causes of Down Syndrome Down syndrome is a chromosomal disorder in which there is an extra copy of chromosome 21 in the cells of the developing fetus.

    ^ Degrading Down Syndrome Information: Frequently Asked Questions (FAQ) Down syndrome is a chromosomal disorder in which there is an extra copy of chromosome 21 in the cells of the developing fetus.

    ^ X Chromosome Down Syndrome Information: Characteristics of Down Syndrome Down syndrome is a chromosomal disorder in which there is an extra copy of chromosome 21 in the cells of the developing fetus.

    Features depend on the origin of the extra genetic material. .Cat-eye syndrome and isodicentric chromosome 15 syndrome (or Idic15) are both caused by a supernumerary marker chromosome, as is Pallister-Killian syndrome.
  • Triple-X syndrome (XXX).^ Y Chromosome Down Syndrome Information: Causes of Down Syndrome Down syndrome is a chromosomal disorder in which there is an extra copy of chromosome 21 in the cells of the developing fetus.

    ^ Chromosome Klinefelter Syndrome--When Your Baby Boy Has a Chromosome Abnormality This syndrome affects only males and is caused by the wrong number of chromosomes upsetting the natural balance of the body.

    ^ Dogma Edwards Syndrome and Chromosome 18 Edwards' syndrome is a disease that is caused by a gene abnormality, where a person has a third copy of chromosome eighteen.

    XXX girls tend to be tall and thin. They have a higher incidence of dyslexia.
  • Turner syndrome (X instead of XX or XY). .In Turner syndrome, female sexual characteristics are present but underdeveloped.^ Speech Delays Finding Information Online About Turner's Syndrome Turner's Syndrome is an inherited, chromosome disorder that only affects females.

    People with Turner syndrome often have a short stature, low hairline, abnormal eye features and bone development and a "caved-in" appearance to the chest.
  • XYY syndrome. XYY boys are usually taller than their siblings. Like XXY boys and XXX girls, they are somewhat more likely to have learning difficulties.
  • Wolf-Hirschhorn syndrome, which is caused by partial deletion of the short arm of chromosome 4. It is characterized by severe growth retardation and severe to profound mental health issues.
.Chromosomal mutations produce changes in whole chromosomes (more than one gene) or in the number of chromosomes present.^ We have one less chromosome than apes.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

^ Chromosomal mutations produce changes in whole chromosomes (more than one gene) or in the number of chromosomes present.
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

^ The progeny obtained from the treated plants produced a number of abnormal phenotypes, the same as, or similar to, known mutations.
  • Fluoride's Mutagenicity (Genotoxicity) 19 January 2010 9:53 UTC www.fluoridealert.org [Source type: Academic]

  • Deletion – loss of part of a chromosome
  • Duplication – extra copies of a part of a chromosome
  • Inversion – reverse the direction of a part of a chromosome
  • Translocation – part of a chromosome breaks off and attaches to another chromosome
.Most mutations are neutral – have little or no effect.^ In sum, the mutations of bacteria and viruses are merely hereditary fluctuations around a median position; a swing to the right, a swing to the left, but no final evolutionary effect.” .
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

Chromosomal aberrations are the changes in the structure of chromosomes. It has a great role in evolution. .A detailed graphical display of all human chromosomes and the diseases annotated at the correct spot may be found at[49].^ Two 3D multiplex FISH (M-FISH) protocols were used for the differential coloring of all 24 human chromosome types (22 autosomes plus X and Y).
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

^ Why the diseases that plague you now may not be all your fault after all.

^ Figure 3 displays the positive correlation obtained in quiescent human fibroblasts for the mean normalized radial CN–CT distances and the DNA content of the chromosomes.
  • PLoS Biology: Three-Dimensional Maps of All Chromosomes in Human Male Fibroblast Nuclei and Prometaphase Rosettes 19 January 2010 9:53 UTC www.plosbiology.org [Source type: Academic]

Human chromosomes

.Chromosomes can be divided into two types--autosomes, and sex chromosomes.^ Autosome A chromosome not involved in sex determination.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Chromosomes Biology Concepts: Meiosis Meiosis is the process in which sex cells divide into four daughter cells, each with a haploid chromosomes (half the normal amount).

^ The human genome consists of 22 pairs of autosomes, and one pair of sex chromosomes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.Certain genetic traits are linked to your sex, and are passed on through the sex chromosomes.^ Genetic Counseling Cystic Fibrosis and the Genetic Link with Chromosome 7 This article discusses the inheritance of the Cystic Fibrosis gene and the symptoms, treatments and the global statistics of the disease.

^ Y Chromosome A Look at Genetic Genealogy DNA analysis can help family historians break through brick walls and uncover information on genetic disorders and disease.

^ Chromosome Fragile X Synrome Fragile X syndrome is a genetic disorder that is passed from parent to child through the X chromosome.

The autosomes contain the rest of the genetic hereditary information. .All act in the same way during cell division.^ Gap phase G1 and G2 phases in cell division, during which there is no DNA synthesis.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Mitosis The process of chromosome segregation that occurs during the division of eukaryotic cells.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ S Top S phase The stage of the cell division cycle during which DNA is synthesized.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.Human cells have 23 pairs of large linear nuclear chromosomes, (22 pairs of autosomes and one pair of sex chromosomes) giving a total of 46 per cell.^ The human genome consists of 22 pairs of autosomes, and one pair of sex chromosomes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Autosome A chromosome not involved in sex determination.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Chromosomes Biology Concepts: Meiosis Meiosis is the process in which sex cells divide into four daughter cells, each with a haploid chromosomes (half the normal amount).

.In addition to these, human cells have many hundreds of copies of the mitochondrial genome.^ Several copies of the mitochondrial genome are found in each organelle.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ More Chimp-Human Genome Problems – Cornelius Hunter Excerpt: Even more interesting, at these locations the chimp’s genome is quite similar to other primates–it is the human that differs from the rest, not the chimp.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

.Sequencing of the human genome has provided a great deal of information about each of the chromosomes.^ Sequencing of the human genome has provided a great deal of information about each of the chromosomes.
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

^ Below is a table compiling statistics for the chromosomes, based on the Sanger Institute 's human genome information in the Vertebrate Genome Annotation (VEGA) database.
  • Chromosome encyclopedia topics | Reference.com 19 January 2010 9:53 UTC www.reference.com [Source type: Academic]

^ (If found, it would provide support for the hypothesis that two short ancestral chromosomes joined to create human chromosome 2; if not found, it would support the idea that the two ancestral chromosomes did not join, or if they did, that their telomeres may have been lost.
  • NOVA Online | Teachers | Classroom Activity | Judgment Day: Intelligent Design on Trial | PBS 20 September 2009 15:32 UTC www.pbs.org [Source type: FILTERED WITH BAYES]

.Below is a table compiling statistics for the chromosomes, based on the Sanger Institute's human genome information in the Vertebrate Genome Annotation (VEGA) database.^ The Human Body Straight from the Horse's Mouth: First Draft of Horse Genome Sequenced The first draft of the horse genome sequence has been deposited in public databases and is freely available to researchers.

^ The human genome consists of 22 pairs of autosomes, and one pair of sex chromosomes.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Curators remove redundancy from submitted data, incorporate annotations, and add reference information and links to external databases.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

[50] .Number of genes is an estimate as it is in part based on gene predictions.^ The criteria governing the gene classification were based on the results of the integrated results of computational analysis using exon prediction programs and sequence similarity searches.
  • The DNA sequence of human chromosome 21 : Article : Nature 20 September 2009 15:32 UTC www.nature.com [Source type: Academic]

^ Yes, the prediction being based on the fact that we are supposed to be closely related to chimps, and therefore should have the same number of chromosomes.
  • A Bogey Moment: The Human Chromosome Count | Uncommon Descent 20 September 2009 15:32 UTC www.uncommondescent.com [Source type: FILTERED WITH BAYES]

^ Chromosome walking A strategy for locating a gene based on sequencing a panel of overlapping clones that span the estimated location of a gene.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

.Total chromosome length is an estimate as well, based on the estimated size of unsequenced heterochromatin regions.^ The euchromatin corresponds to regions in which the chromosomes are dispersed, and the heterochromatin to the regions in which chromosomes are condensed.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

^ Chromosome walking A strategy for locating a gene based on sequencing a panel of overlapping clones that span the estimated location of a gene.
  • Drug Discovery & Development - Glossary 19 January 2010 9:53 UTC www.dddmag.com [Source type: Academic]

Genes and bases on chromosomes.png
Chromosome Genes Total bases Sequenced bases[51]
1 4,220 247,199,719 224,999,719
2 1,491 242,751,149 237,712,649
3 1,550 199,446,827 194,704,827
4 446 191,263,063 187,297,063
5 609 180,837,866 177,702,766
6 2,281 170,896,993 167,273,993
7 2,135 158,821,424 154,952,424
8 1,106 146,274,826 142,612,826
9 1,920 140,442,298 120,312,298
10 1,793 135,374,737 131,624,737
11 379 134,452,384 131,130,853
12 1,430 132,289,534 130,303,534
13 924 114,127,980 95,559,980
14 1,347 106,360,585 88,290,585
15 921 100,338,915 81,341,915
16 909 88,822,254 78,884,754
17 1,672 78,654,742 77,800,220
18 519 76,117,153 74,656,155
19 1,555 63,806,651 55,785,651
20 1,008 62,435,965 59,505,254
21 578 46,944,323 34,171,998
22 1,092 49,528,953 34,893,953
X (sex chromosome) 1,846 154,913,754 151,058,754
Y (sex chromosome) 454 57,741,652 25,121,652
Total 32,185 3,079,843,747 2,857,698,560

See also

External links

References

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  50. ^ http://vega.sanger.ac.uk/Homo_sapiens/index.html All data in this table was derived from this database, Nov 11, 2008.
  51. ^ Sequenced percentages are based on fraction of euchromatin portion, as the Human Genome Project goals called for determination of only the euchromatic portion of the genome. Telomeres, centromeres, and other heterochromatic regions have been left undetermined, as have a small number of unclonable gaps. See http://www.ncbi.nlm.nih.gov/genome/seq/ for more information on the Human Genome Project.

Simple English

[[File:|thumb|220px|Diagram of a duplicated and condensed metaphase eukaryotic chromosome.
(1) Chromatid – one of the two parts of the chromosome after duplication.
(2) Centromere – the point where the two chromatids touch.
(3) Short arm. (4) Long arm.]] The chromosomes of a cell are in the cell nucleus. They carry the genetic information. Chromosomes are made up of DNA and protein combined as chromatin. Each chromosome contains many genes. Chromosomes come in pairs: one set from the mother; the other set from the father. Cytologists label chromosomes with numbers.[1]

Chromosomes are present in every cell nucleus. This means they are found in all eukaryotes, since only eukaryotes have cell nuclei. When eukaryote cells divide, the chromosomes also divide. When a somatic (body) cell (such as a muscle cell) divides, the process is called mitosis. Before mitosis, the cell copies all the chromosomes and then it can divide. When they duplicate, chromosomes look like the letter "X". They are called chromatids when they are doubled (see diagram).

There are 46 chromosomes in a human, 23 pairs. Everyone has a set of chromosomes from their father, and a matching set from their mother. They include a pair of sex chromosomes. The mother's eggs always contain an X chromosome, while the father's sperm contains either a Y chromosome or an X chromosome. That determines the sex of the child. To produce sex cells (gametes), the stem cells go through a different division process called meiosis. This reduces the 23 pairs (diploid) to 23 singles (haploid). These, when combined by fertilisation, produce the new set of 23 pairs.

Different animals have different numbers of chromosomes. If a person does not have the usual number of chromosomes, they may die or have one or more peculiarities. For example, they might get a genetic disorder like Down syndrome (extra chromosome 21) and Klinefelter's syndrome (a male with two X chromosomes). Some genetic disorders are more common than others.

References

  1. White M.J.D. 1973. The chromosomes, 6th ed. London: Chapman and Hall


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