cell death Flashcards
why is cell death necessary?
it is needed for regulation and it helps get rid of unwanted things in the body
describe apoptosis
it is programmed cell death with no resulting inflammation. cellular content does not leak into the open space, rather DNA is fragmented and packaged into apoptotic bodies
describe necrosis
it is cell death due to injury, heat, lack of oxygen, and infection. cellular contents leak due to damage to plasma membrane. swelling and bursting causes inflammation.
what is the different methods of apoptosis
suicide: an absence of trophic factors, or factors that keep the cell living and working
murder: presence of a killing signal where one cell activates a killing signal in another cell and kills it
what enzyme mediates cell death?
caspases
how do caspases meditate cell death?
they use calcium to cut the c terminal to aspartic acid. they begin as procaspase which is cleaved and then an activated caspase (anything with aspartic acid gets cut)
what are the two types of capsases?
initiator (caspase 8 and 9) and executioner (caspase 3, 6, 7)
how is apoptosis initiated?
- cytochrome c is released from the intermembrane space of mitochondria
- cytochrome c binds to APAF1 adaptor protein
- binded cyt c and APAF1 oligomerize and recruit procaspase-9 molecules
- this forms a apoptosome (cyt c, APAF1, and procaspase-9)
- activation of procaspase-9 within apoptosome causes caspase cascade (activation of executioner caspases) leading to apoptosis
Bcl-2/Bcl-xL
inhibit Bak/Bax to form channel that release cyt c
Bim, Puma, Bad
remove Bcl-2 and Bcl-xL to allow Bak/Bax to form channel to allow cytochrome c to be released
DNA damage (ex: cell exposed to radiation) induces expression of _____
Puma
Bim binds to and inhibits
Bcl-2/Bcl-xL
SMAC/DIABLO
pro-apoptotic
inhibit XIAP
XIAP
inhibitor of apoptosis by inhibiting activation of caspase inhibitors and effectors
caspase 8 and 9 activity occurs in
parallel to ensure rapid dispersion of cell signal
