Clone (cell biology)
You don't need to be Editor-In-Chief to add or edit content to WikiDoc. You can begin to add to or edit text on this WikiDoc page by clicking on the edit button at the top of this page. Next enter or edit the information that you would like to appear here. Once you are done editing, scroll down and click the Save page button at the bottom of the page.
Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1] Phone:617-525-6884
Please Take Over This Page and Apply to be Editor-In-Chief for this topic: There can be one or more than one Editor-In-Chief. You may also apply to be an Associate Editor-In-Chief of one of the subtopics below. Please mail us [2] to indicate your interest in serving either as an Editor-In-Chief of the entire topic or as an Associate Editor-In-Chief for a subtopic. Please be sure to attach your CV and or biographical sketch.
A clone is a group of identical cells that share a common ancestry, meaning are derived from the same mother cell.[1]
Clonality implies the state of a cell or a substance being derived from one source or the other. Thus there are terms like polyclonal--derived from many clones; oligoclonal[1]--derived from a few clones; and, monoclonal--derived from one clone. These terms are most commonly used in context of antibodies or immunocytes.
Contexts
This concept of clone assumes importance as all the cells that form a clone share common ancestry with a very important consequence--shared genotype.
- One of the most prominent usage is in describing a clone of B cells. The B cells in the body have two important phenotypes (functional forms)--the antibody secreting, terminally differentiated (that is, they cannot divide further) plasma cells, and the memory and the naive cells, both of which retain their proliferative potential.
- Another important area where one can talk of "clones" of cells is neoplasms.[1] Many of the tumors derive from one (sufficiently) mutated cell, so they are technically a single clone of cells. However, during course of cell division, one of the cells can get mutated further and acquire new characteristics to diverge as a new clone. This is how, in fact, drug resistance could be acquired in many cases.
- All the granulosa cells in a Graafian follicle are in fact a clone.
- Paroxysmal nocturnal hemoglobinuria is a disorder of bone marrow cells resulting in shortened life of red blood cells, which is also a result of clonal expansion, i.e., all the altered cells are originally derived from a single cell, which also somewhat compromises the functioning of other "normal" bone marrow cells.[1]
Basis of clonal proliferation
Most of the other cells cannot divide indefinitely as after a few cycles of cell division the cells stop expressing an enzyme telomerase. The genetic material in form of deoxyribonucleic acid (DNA) keeps on getting shortened with each cell division, and cells stop dividing when they sense that their DNA is critically shortened. However, this enzyme in "youthful" cells replaces these lost bits (nucleotides) of DNA thus making almost unlimited cycles of cell division possible. It is believed that the above mentioned tissues have a constitutional elevated expression of telomerase. When ultimately many cells are produced by a single cell, clonal expansion is said to have taken place.
Concept of clonal colony
A somewhat similar concept is that of clonal colony (also called a genet), wherein the cells (usually unicellular) also share a common ancestry, but which also requires the products of clonal expansion to reside at "one place", or in close proximity. A clonal colony would be well exemplified by a bacterial culture colony, or the bacterial films that are more likely to be found in vivo (in infected multicellular hosts). Whereas, the cells of clones dealt with here are specialized cells of a multicellular organism (usually vertebrates), and may be residing at quite distant places. For instance, two plasma cells belonging to the same clone could be derived from different memory cells (in turn with shared clonality), and be residing in quite distant locations like the cervical (in the neck) and inguinal (in the groin) lymph nodes.
See also
References
Into Matter |
|---|
| Organism → System → Organ → Tissue → Cell → Organelle → Molecule → Atom → Subatomic particle (Composite particle . Elementary particle) |
Cell Potency |
|---|
← More Potent ... Less Potent → |
Acknowledgement and Attribution Regarding Sources of Content
Some of the initial content on this page may be incorporated in part from copyleft sources in the public domain including wikis such as Wikipedia and AskDrWiki. Drug information for patients came from the The National Library of Medicine. Infectious disease information may have come from the Centers for Disease Control (CDC). Differential Diagnoses are drawn from clinicians as well as an amalgamation of 3 sources: 1.The Disease Database; 2. Kahan, Scott, Smith, Ellen G. In A Page: Signs and Symptoms. Malden, Massachusetts: Blackwell Publishing, 2004:3; 3. Sailer, Christian, Wasner, Susanne. Differential Diagnosis Pocket. Hermosa Beach, CA: Borm Bruckmeir Publishing LLC, 2002:7 .
