Cell biology (formerly cytology, from the Greek kytos, "container") is an academic discipline that studies cells – their physiological properties, their structure, the organelles they contain, interactions with their environment, their life cycle, division and death. This is done both on a microscopic and molecular level. Cell biology research encompasses both the great diversity of single-celled organisms like bacteria and protozoa, as well as the many specialized cells in multicellular organisms like humans.
Knowing the components of cells and how cells work is fundamental to all biological sciences. Appreciating the similarities and differences between cell types is particularly important to the fields of cell and molecular biology as well as to biomedical fields such as cancer research and developmental biology. These fundamental similarities and differences provide a unifying theme, sometimes allowing the principles learned from studying one cell type to be extrapolated and generalized to other cell types. Hence, research in cell biology is closely related to genetics, biochemistry, molecular biology, Immunology, and developmental biology.
Each type of protein is usually sent to a particular part of the cell. An important part of cell biology is the investigation of molecular mechanisms by which proteins are moved to different places inside cells or secreted from cells.
Most proteins are synthesized by ribosomes in the cytoplasm. This process is also known as protein biosynthesis or simply protein translation. Some proteins, such as those to be incorporated in membranes (known as membrane proteins), are transported into the "rough" endoplasmic reticulum (ER) during synthesis. This process can be followed by transportation and processing in the Golgi apparatus. From the Golgi, membrane proteins can move to the plasma membrane, to other subcellular compartments, or they can be secreted from the cell. The ER and Golgi can be thought of as the "membrane protein synthesis compartment" and the "membrane protein processing compartment", respectively. There is a semi-constant flux of proteins through these compartments. ER and Golgi-resident proteins associate with other proteins but remain in their respective compartments. Other proteins "flow" through the ER and Golgi to the plasma membrane. Motor proteins transport membrane protein-containing vesicles along cytoskeletal tracks to distant parts of cells such as axon terminals.
Some proteins that are made in the cytoplasm contain structural features that target them for transport into mitochondria or the nucleus. Some mitochondrial proteins are made inside mitochondria and are coded for by mitochondrial DNA. In plants, chloroplasts also make some cell proteins.
Extracellular and cell surface proteins destined to be degraded can move back into intracellular compartments upon being incorporated into endocytosed vesicles. Some of these vesicles fuse with lysosomes where the proteins are broken down to their individual amino acids. The degradation of some membrane proteins begins while still at the cell surface when they are cleaved by secretases. Proteins that function in the cytoplasm are often degraded by proteasomes.
Several different techniques exist to study cells.
Purification of cells and their parts Purification may be performed using the following methods:
This is the main page for the Cell Biology course, in the Department of Cell Biology. Cell biology is typically one of the specialized courses taken by students after they have had a more general introduction to modern biology. A basic introduction to biology, as can be gained from Michael McDarby's Online Introduction to Biology or the General Biology textbook at Wikibooks, is a possible prerequisite. Chemistry is the backbone of Cellular Biology so some knowledge of Biochemistry is necessary for the concepts. Check out these sites for more information chemistry or biochemistry. However, Cell Biology is fundamental to all of biology, and can serve as a reasonable starting point for students exploring the field.
It seems that many people checking out this page are looking to supplement their coursework. Which was what I was looking for too when I found this site. I have added lectures that are the equivalent to the college course normally offered a junior or senior level. It correlates with the free video lectures available on ITunes U. I would love for someone to post additional resources, notes or comments. This can be a resource that will help other students share information for years to come. As you can tell from below, there are lectures with a more general aim and then the lectures that delve more deeply into the subject and require a greater knowledge of biochemistry.
Lesson 1: Introduction to Cell Biology
Lesson 2: Membrane Structure: Lipids
Lesson 3: Membrane Structure: Proteins
Lesson 4: Membrane Structure: Dynamics
Lesson 7: Membrane Assembly: Signal Hypothesis
Lesson 8: Membrane Assembly: Mechanism
Lesson 9: Membrane Assembly: Topography
Lesson 10: Cholesterol Regulation
Lesson 11: Membrane Vesicular Transport
Lesson 12: Lysosomal Protein Transport
Lesson 13: Action Potential
Lesson 14: Synaptic Transmission
Lesson 15: Membrane Fusion
Lesson 16: Visualizing Cells: Principles of Microscopy
Lesson 18: Actin-binding Proteins and Cell Migration
Lesson 21: Cell Adhesion, Motility and Division
Lesson 22: Intermediate Filaments and Septins
Lesson 25: Nuclear and Chromatin Structure
Lesson 26: Mitosis and Cell Division
Lesson 27: Mitotic Spindle Assembly and Function
Lesson 28: Meiosis
Lesson 29: Cell Communication: Ligand and Receptors
Lesson 30: Receptors
Lesson 31: G-Protein Coupled Receptor Signaling I
Lesson 32: G-Protein Coupled Receptor Signaling II
Lesson 33: Receptor Tyrosine Kinase Signaling
Lesson 34: The Ras-MAP Kinase Pathway
Lesson 35: Regulation of Cell Growth
Lesson 36: The Cell Cycle I
Lesson 37: The Cell Cycle II
Lesson 38: The Cell Cycle III
Lesson 39: Checkpoints
Lesson 40: Apoptosis
Lesson 41: Cancer
Lesson 42: Cancer Review
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(note: all of the above were added when this page existed at Wikibooks)
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Cell biology is the study of how living cells work. This includes the structure and function of the cell organelles, and the carbon-based molecules which cells produce. The most important molecules are DNA, RNA and proteins.
The most important structures in the cell are the nucleus and the chromosomes, but there are many others. The structure of eukaryotic cells is much more complex than prokaryotic cells. This is because endosymbiosis has occurred: some or all of the eukaryote organelles are former prokaryotes. Examples are mitochondria and plastids.
The most important function of cells is to divide by mitosis or meiosis. Cells in a multicellular organism also specialise in different functions, and the different types may look quite to each other.