Cell biology

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Cell biology (also called cellular biology or formerly cytology, from the Greek kytos, "container") is an academic discipline that studies cells. This includes 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 extends to both the great diversity of single-celled organisms like bacteria and the many specialized cells in multicellular organisms like humans.

Knowing the composition of cells and how cells work is fundamental to all of the biological sciences. Appreciating the similarities and differences between cell types is particularly important to the fields of cell and molecular biology. These fundamental similarities and differences provide a unifying theme, allowing the principles learned from studying one cell type to be extrapolated and generalized to other cell types. Research in cell biology is closely related to genetics, biochemistry, molecular biology and developmental biology.

Image:NIEHScell.jpg

1 Processes
- 1.1 Movement of proteins
- 1.2 Other cellular processes
2 Techniques
- 2.1 Purification of cells and their parts
3 Some structures inside cells
4 See also
- 4.1 Notable cell biologists
5 References
6 External links
- 6.1 Online cell biology textbooks

[edit] Processes

[edit] Movement of proteins

Image:FluorescentCells.jpg

Every cell typically contains hundreds of different kinds of macromolecules that function together to generate the behavior of the cell. Each type of protein is usually sent to a particular part of the cell. An important part of cell biology is 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 (membrane proteins), are transported into the ER during synthesis and further processed 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 mebrane 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.

[edit] Other cellular processes

Cell division - The origin of new cells.
Cell signaling - Regulation of cell behavior by signals from outside.
Active transport and Passive transport - Movement of molecules into and out of cells.
Adhesion - Holding together cells and tissues.
Transcription and mRNA splicing - gene expression.
Cell movement: Chemotaxis, Contraction, cilia and flagella
DNA repair and Cell death
Metabolism: Glycolysis, respiration, Photosynthesis

[edit] Techniques

Microscopy and Immunostaining
Gene knockdown and Transfection
Cell culture and Radioactive tracers
PCR and In situ hybridization
DNA microarray screens of gene expression

[edit] Purification of cells and their parts

Purification of cells and their parts is achieved in the following ways:

Flow cytometry
Cell fractionation
- Release of cellular organelles by disruption of cells.
- Separation of different organelles by centrifugation.
Proteins extracted from cell membranes by detergents and salts or other kinds of chemicals.
Immunoprecipitation

[edit] Some structures inside cells

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Organelle - term used for major subcellular structures
Chloroplast - key organelle for photosynthesis
Cilia - motile microtubule-containing structures of eukaryotes
Cytoplasm - contents of the main fluid-filled space inside cells
Cytoskeleton - protein filaments inside cells
Ribosome - RNA and protein complex required for protein synthesis in cells
Endoplasmic reticulum - major site of membrane protein synthesis
Flagella - motile structures of bacteria, archaea and eukaryotes
Golgi apparatus - site of protein glycosylation in the endomembrane system
Membrane lipid and protein barrier
Lipid bilayer - fundamental organizational structure of cell membranes
Vesicle - small membrane-bounded spheres inside cells
Mitochondrion - major energy-producing organelle
Nucleus - holds most of the DNA of eukaryotic cells

[edit] See also

[edit] Notable cell biologists

[edit] References

This article contains material from the Science Primer published by the NCBI, which, as a US government publication, is in the public domain.

[edit] External links

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Wikibooks has more on the topic of

Cell biology

American Society for Cell Biology
British Society for Cell Biology
BMC Cell Biology - online journal, open access
Journal of Cell Biology - older issues free
Journal of Cell Science - older issues free
Cell Biology - School and University - graphics
Cell Biology News

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Wikiversity has learning resources related to this subject:

Cell biology

[edit] Online cell biology textbooks

Molecular Biology of the Cell fourth edition, edited by Bruce Alberts (2002) published by Garland Science.
Molecular Cell Biology fourth edition, edited by Harvey Lodish (2000) published by W. H. Freeman and Company.
The Cell - A Molecular Approach second edition, by Geoffrey M. Cooper (2000) published by Sinauer Associates.
MIT Hypertext Cell Biology

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