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Senescence: Difference between revisions
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There are three different ways that a cell can start the process of apoptosis. The first is to trigger it by sending internal signals through the mitochondrial pathway. The second way is through external signals through the death receptor pathway. Finally, the cell can trigger apoptosis through an inducing factor. [http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/Apoptosis.html] | There are three different ways that a cell can start the process of apoptosis. The first is to trigger it by sending internal signals through the mitochondrial pathway. The second way is through external signals through the death receptor pathway. Finally, the cell can trigger apoptosis through an inducing factor. [http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/A/Apoptosis.html] | ||
{| | {| border="1" cellpadding="2" | ||
|- | !width="20"| '''Space''' | ||
In a healthy cell, the outer membranes of its mitochondria display the protein Bcl-2 on their surface. | !width="20"| '''Time''' | ||
Internal damage to the cell (e.g., from reactive oxygen species) causes | |- | ||
| | |||
| In a healthy cell, the outer membranes of its mitochondria display the protein Bcl-2 on their surface. | |||
|- | |||
| | |||
| Internal damage to the cell (e.g., from reactive oxygen species) causes | |||
Bcl-2 to activate a related protein, Bax, which punches holes in the outer mitochondrial membrane, causing | Bcl-2 to activate a related protein, Bax, which punches holes in the outer mitochondrial membrane, causing | ||
cytochrome c to leak out. | cytochrome c to leak out. | ||
The released cytochrome c binds to the protein Apaf-1 ("apoptotic protease activating factor-1"). | |- | ||
| | |||
| The released cytochrome c binds to the protein Apaf-1 ("apoptotic protease activating factor-1"). | |||
|} | |||
Using the energy provided by ATP, | Using the energy provided by ATP, | ||
these complexes aggregate to form apoptosomes. | these complexes aggregate to form apoptosomes. | ||
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degradation of chromosomal DNA, and | degradation of chromosomal DNA, and | ||
phagocytosis of the cell. | phagocytosis of the cell. | ||
== Senesence Hormones == | == Senesence Hormones == | ||
