Download Cell senescence questions

Cell senescence questions. See chapter 4.
What does cell senescence and replicative senescence actually mean? Is it a good
thing?
Replicative senescence refers to the cellular response to repeated cell division (ie
shortening telomeres make the cell know that it has undergone plenty of divisions)
Senescence is a broader category. Rep. senescence is an example of cellular senescence.
Cellular senescence refers to the cell response to any of many stimuli. (cell
division/shortening telomeres is just one of these stimuli. Others include DNA damage,
oxidative stress, etc) See p. 47-p.48
However, senescent cells still produce mRNA and proteins, so they are not really DEAD
per se. It is a good thing because it protects against cancer (having short telomeres allows
for bridging of chromosomes that can lead to genetic instability) but it is also a bad thing
because senescence may contribute to the aging phenotype. (p. 55-56)
Does senescence prevent cancer? and by what mechanisms?
Senescence prevents cancer by not allowing cells to “hang around” and actively replicate
after they have been damaged or telomeres have become too short. (p. 55)
What is oncogene expression and does it promote senescence? Does it prevent or
promote cancer cells?
Oncogenes are genes that promote cancerous growth. Oncogenes have actually been
shown to block the senescent response, thereby preventing the protective senescent
response against cancer. (p. 55)