Cell biology
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:''See also [[List of basic cell biology topics]].''
'''Cell biology''' (also called '''cellular biology''' or formerly '''cytology''', from the [[Greek language|Greek]] ''kytos'', "container") is an [[list of academic disciplines|academic discipline]] that studies [[cell (biology)|cell]]s – their [[physiology|physiological]] properties, their structure, the [[organelles]] they contain, interactions with their environment, their [[cell cycle|life cycle]], [[cell division|division]] and [[apoptosis|death]]. This is done both on a [[microscope|microscopic]] and [[molecule|molecular]] level. [[Cell (biology)|Cell]] biology research extends to both the great diversity of single-celled organisms like [[bacterium|bacteria]] and the many specialized cells in multicellular [[organisms]] like [[human]]s.
Knowing the composition of cells and how cells work is fundamental to all of the [[biology|biological sciences]]. Appreciating the similarities and also 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|thumb|right|300px|Understanding cells in terms of their molecular components.]]
==Processes==
===Movement of proteins===
[[Image:FluorescentCells.jpg|thumb|left|Proteins (red and green stain) at different locations in a cell.]]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 [[protein]]s are synthesized by [[ribosome]]s in the [[cytoplasm]]. This process is also known as [[protein biosynthesis]] or simply [[translation (genetics)|protein translation]]. Some proteins, such as those to be incorporated in membranes (known as [[membrane protein]]s), are transported into the [[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. [[Kinesin|Motor proteins]] transport membrane protein-containing vesicles along [[cytoskeleton|cytoskeletal]] tracks to distant parts of cells such as [[axon]] terminals.
Some proteins that are made in the cytoplasm contain [[Nuclear Localization Signal|structural features]] that target them for transport into [[mitochondria]] or the [[nucleus (cell)|nucleus]]. Some mitochondrial proteins are made inside mitochondria and are coded for by mitochondrial DNA. In plants, [[chloroplast]]s also make some cell proteins.
Extracellular and cell surface proteins destined to be degraded can move back into intracellular compartments upon being incorporated into [[Clathrin|endocytosed]] vesicles. Some of these vesicles fuse with [[lysosome]]s where the proteins are broken down to their individual [[amino acid]]s. The degradation of some membrane proteins begins while still at the cell surface when they are cleaved by [[secretase]]s. Proteins that function in the cytoplasm are often degraded by [[proteasome]]s.
===Other cellular processes===
*[[Cell division]] - a cell division process called mitosis.
*[[Cell signaling]] - Regulation of cell behavior by signals from outside.
*[[Active transport]] and [[Passive transport]] - Movement of molecules into and out of cells.
*[[Cell adhesion|Adhesion]] - Holding together cells and tissues.
*[[Transcription (genetics)|Transcription]] and [[Splicing (genetics)|mRNA splicing]] - gene expression.
*Cell movement: [[Chemotaxis]], [[Muscle contraction|Contraction]], [[cilia]] and [[Flagellum|flagella]]
*[[DNA repair]] and [[Cell death]]
*[[Metabolism]]: [[Glycolysis]], [[Cellular respiration|respiration]], [[Photosynthesis]]
*[[Autophagy]] - The process whereby cells "eat" their own internal components or microbial invaders
==Internal cellular structures==
[[Image:Electronmicroscopynhlbi.jpg|thumb|right|Electronmicrograph.]]
*[[Organelle]] - term used for major subcellular structures
*[[Chloroplast]] - key [[organelle]] for [[photosynthesis]]
*[[Cilia]] - motile [[microtubule]]-containing structures of [[eukaryote]]s
*[[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
*[[cell membrane|Membrane]] [[lipid]] and [[protein]] barrier
*[[Lipid bilayer]] - fundamental organizational structure of [[cell membrane]]s
*[[vesicle (biology)|Vesicle]] - small membrane-bounded spheres inside cells
*[[Mitochondrion]] - major energy-producing organelle
*[[Cell nucleus|Nucleus]] - holds most of the [[DNA]] of eukaryotic cells
==Techniques used to study cells==
[[Image:Drosophila m oogenesis.png|thumb|right|300px]]
'''Cells may be observed under the microscope'''. This includes the [[Optical Microscope]], [[Transmission Electron Microscope]], [[Scanning Electron Microscope]], [[Fluorescence Microscope]], and by [[Confocal Microscopy]].
[[Immunostaining]] can also be imploded to observe cells. Such examples are:
*[[Gene knockdown]] and [[Transfection]]
*[[Cell culture]] and [[Radioactive tracer]]s
*[[PCR]] and [[In situ hybridization]]
*[[DNA microarray]] screens of gene expression
*[[Computational genomics]] approaches are used to find patterns in genomic information <ref>Cristianini, N. and Hahn, M. [http://www.computational-genomics.net/ ''Introduction to Computational Genomics''], Cambridge University Press, 2006. (ISBN-13: 9780521671910 | ISBN-10: 0521671914)</ref>
'''Purification of cells and their parts'''
Purification may be performed using the following methods:
*[[Flow cytometry]]
*[[Cell fractionation]]
**Release of cellular organelles by disruption of cells.
**Separation of different organelles by [[centrifugation]].
*Proteins extracted from [[cell membrane]]s by [[detergent]]s and [[salt]]s or other kinds of chemicals.
*[[Immunoprecipitation]].
==See also==
*[[List of basic cell biology topics]]
*[[Cell disruption]]
*[[List of publications in biology#Cell biology|Important publications in cell biology]]
*[[Institute of Molecular and Cell Biology]]
*[[The American Society for Cell Biology]]
===Notable cell biologists===
[[Image:Palade01.jpg|thumb|right|[[George Emil Palade]]]]
*[[Robert Hooke]]
*[[Anton van Leeuwenhoek]]
*[[Günter Blobel]]
*[[Marc Kirschner]]
*[[Peter Agre]]
*[[Keith R. Porter]]
*[[Ira Mellman]]
*[[Paul Nurse]]
*[[H. Robert Horvitz]]
*[[Christian de Duve]]
*[[Edmund Beecher Wilson]]
*[[Peter D. Mitchell]]
*[[Michael Swann]]
*[[George Emil Palade]]
*[[Geoffrey M. Cooper]]
==References==
*Cell and Molecular Biology by Karp 5th Ed.
*{{NCBI-scienceprimer}}
{{reflist}}
==External links==
{{Wikibooks}}
*[http://www.ascb.org/ American Society for Cell Biology]
*[http://www.kcl.ac.uk/kis/schools/life_sciences/biomed/bscb/top.html British Society for Cell Biology]
*[http://www.cellsalive.com/cells/cell_model.htm Cells Alive]
*[http://www.biomedcentral.com/1471-2121/ BMC Cell Biology] - online journal, open access
*[http://www.jcb.org/contents-by-date.0.shtml Journal of Cell Biology] - older issues free
*[http://jcs.biologists.org/contents-by-date.0.shtml Journal of Cell Science] - older issues free
*[http://www.zytologie-online.net/ Cell Biology - School and University - graphics]
*[[Nature Reviews Molecular Cell Biology]] ([http://www.nature.com/nrm/index.html journal home])
*[http://www.biochemweb.org/ The Virtual Library of Biochemistry and Cell Biology]
*[http://www.centreofthecell.org/ Centre of the Cell online resource]
*[http://www.springerprotocols.com Springer Protocols] for cell biology research
<div class="infobox sisterproject">
<div style="float: left;">[[Image:Wikiversity-logo.svg|50px|none|Wikiversity]]</div>
<div style="margin-left: 60px;">[[Wikiversity]] has learning resources related to this subject:<div style="margin-left: 10px;">'''''[[v:{{{1|Special:Search/Cell biology}}}|{{{1|Cell biology}}}]]'''''</div>
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===Online cell biology textbooks===
*''[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=cell+biology+AND+mboc4%5Bbook%5D+AND+373693%5Buid%5D&rid=mboc4 Molecular Biology of the Cell]'' fourth edition, edited by Bruce Alberts (2002) published by Garland Science.
*''[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=cell+biology+AND+mcb%5Bbook%5D+AND+105032%5Buid%5D&rid=mcb.chapter.145 Molecular Cell Biology]'' fourth edition, edited by Harvey Lodish (2000) published by W. H. Freeman and Company.
*''[http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Search&db=books&doptcmdl=GenBookHL&term=cell+biology+AND+cooper%5Bbook%5D+AND+165077%5Buid%5D&rid=cooper.chapter.89 The Cell - A Molecular Approach]'' second edition, by Geoffrey M. Cooper (2000) published by Sinauer Associates.
<!--*[http://web.mit.edu/esgbio/www/cb/cbdir.html MIT Hypertext Cell Biology] Now defunct see <nowiki>[http://web.mit.edu/esgbio/www/]</nowiki>-->
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