Posted On : 09.06.2017 02:51 pm
Chapter: Biotechnology Applying the Genetic Revolution: Aging and Apoptosis
Factors That Activate Senescence
Many different factors activate senescence in cells and have been implicated in the aging process.
THAT ACTIVATE SENESCENCE
Many different factors activate
senescence in cells and have been implicated in the aging process. In normal
cells, the length of the telomeres controls whether or not cells senesce.
During the replication of chromosomes, DNA polymerase cannot replicate the DNA
at the distal tips of the chromosomes. Consequently, each chromosome shortens each
time the cell divides ( Fig. 20.1 ). When the telomeres reach a critically
short length, the cell enters senescence.
Another factor that activates senescence
and may contributeto aging is DNA damage. Normal metabolic activity produces a
variety of reactive oxygen metabolites (ROM) that attack various proteins, lipids,
and the DNA. This damage accumulates until it reaches a threshold. After that
point, the cells may initiate senescence or apoptosis, depending on the severity
and extent of the damage ( Fig. 20.2 ). Consequently, highly defective cells do
not accumulate in the body.
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Biotechnology Applying the Genetic Revolution: Aging and Apoptosis : Factors That Activate Senescence |