110,311
edits
Senescence: Difference between revisions
From CreationWiki, the encyclopedia of creation science
Jump to navigationJump to search
→Apoptosis
No edit summary |
|||
| Line 11: | Line 11: | ||
Senescence is thought to be due to the degradation of [[telomeres]]. Telomeres are caps at the end of [[chromosomes]] that prevent chromosomes from fusing together. After each division of the cell, the length of the telomere shortens. When the telomere is finally gone, the cell cannot divide anymore and dies. [[Cancer]] cells can avoid this eventual death by introducing telomerase into its cells. Telomerase is a reverse-transcriptase enzyme that makes the telomeres longer after each division, thus preventing them from disappearing. [http://www.senescence.info/telomeres.html] | Senescence is thought to be due to the degradation of [[telomeres]]. Telomeres are caps at the end of [[chromosomes]] that prevent chromosomes from fusing together. After each division of the cell, the length of the telomere shortens. When the telomere is finally gone, the cell cannot divide anymore and dies. [[Cancer]] cells can avoid this eventual death by introducing telomerase into its cells. Telomerase is a reverse-transcriptase enzyme that makes the telomeres longer after each division, thus preventing them from disappearing. [http://www.senescence.info/telomeres.html] | ||
{{clearboth}} | |||
== Apoptosis == | == Apoptosis == | ||
:''Main Article: [[Apoptosis]]'' | |||
[[Image:Apoptosis.jpg|thumb|150px|right|Flower dying through apoptosis]] | [[Image:Apoptosis.jpg|thumb|150px|right|Flower dying through apoptosis]] | ||
Programmed cell death is called [[apoptosis]]. This is commonly seen in plants, but can happen in all kinds of organisms. There are two main reasons for an [[organism]] to kill its own cells: It is needed for proper development, and it is needed to destroy cells that pose a threat to the entire organism. This can be seen in the development of the human brain, where synapses must form by getting rid of surplus cells through apoptosis, or destroying cancer cells or cells infected with viruses through induced apoptosis. [http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/Apoptosis.html] | Programmed cell death is called [[apoptosis]]. This is commonly seen in plants, but can happen in all kinds of organisms. There are two main reasons for an [[organism]] to kill its own cells: It is needed for proper development, and it is needed to destroy cells that pose a threat to the entire organism. This can be seen in the development of the human brain, where synapses must form by getting rid of surplus cells through apoptosis, or destroying cancer cells or cells infected with viruses through induced apoptosis. [http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/Apoptosis.html] | ||
| Line 59: | Line 60: | ||
| The activation of these "executioner" caspases creates an expanding cascade of proteolytic activity (rather like that in blood clotting and complement activation) which leads to digestion of structural proteins in the cytoplasm, degradation of chromosomal DNA, and phagocytosis of the cell | | The activation of these "executioner" caspases creates an expanding cascade of proteolytic activity (rather like that in blood clotting and complement activation) which leads to digestion of structural proteins in the cytoplasm, degradation of chromosomal DNA, and phagocytosis of the cell | ||
| | | | ||
|} | |} | ||
== Senesence Hormones == | == Senesence Hormones == | ||
