Apoptsis

Question 1

what happens during apoptosis?

Answer 1

cytoskeleton collapses, nuclear envelope disassembles
nuclear DNA breaks into fragments
phosphatidylserine on cell surface causes phagocytosis

Question 2

how can apoptosis be triggered?

Answer 2

extrinsic pathway- death receptor activation

intrinsic pathway- internal trigger

Question 3

what does an active caspase do?

Answer 3

invoke apoptosis, digest certain proteins

Question 4

how does a caspase get activated?

Answer 4

apoptosis signals clusters inactive caspases. inactive procaspases get their prodomains cleaved. this cleaves executioner caspases then cleave other substrates

Question 5

how does DNA get cleaved?

Answer 5

executioner caspase cleaves inhibitory CAD and then the now active CAD cleaved DNA

Question 6

explain extrinsic pathway

Answer 6

receptors binds with fas ligand thats on a killer lymphocyte. FADD adaptor protein’s death doman binds to receptors death domain. caspase 8’s death effector domain binds to FADD’s death effector domain. receptor+FADD+caspase=DISC. procaspases cluster and cleave each other, activating the caspases

Question 7

explain intrinsic pathway

Answer 7

cytochrome c released from intermembrane space in mitochondria and binds to Apaf 1. CARD domain on Apaf 1 bind on other Apaf 1s and form a wheel looking shit called apoptosome. procaspase 9’s CARD domain binds to apoptosome’s and clusters to cleave each other

Question 8

how is a procaspase different from a caspase?

Answer 8

a procaspase turns into a caspase when they cluster and cleave each other

Question 9

what regulates release of cytochrome c in the intrinsic pathway?

Answer 9

Bcl-2 family

Question 10

what are the 3 categories of the Bcl-2 family?

Answer 10

anti-apoptotic Bcl-2
pro-apoptotic effector
pro-apoptotic BH3-only

Question 11

what are Bcl-2 homology domains?

Answer 11

areas where proteins look similar

Question 12

anti-apoptotic Bcl-2 has what BHs?

Answer 12

all 4, BH4/3/1/2

Question 13

pro-apoptotic effector has what BHs?

Answer 13

BH3/1/2

Question 14

pro-apoptotic BH3-only protein has what BHs?

Answer 14

BH3

Question 15

what does pro-apoptotic effector do?

Answer 15

apoptotic stimulus causes them to aggregate and cluster to releases cytochrome c

Question 16

what does the anti-apoptotic Bcl-2 do?

Answer 16

inhibit pro-apoptotic effector to stop release of cytochrome c

Question 17

what does pro-apoptotic BH3-only do?

Answer 17

inhibits anti-apoptotic Bcl-2 thats inhibits pro-apoptotic effector to stop release of cytochrome c (ALL IN ALL MOVES FORWARD WITH APOPTOSIS) and helps aggregate pro-apoptotic effector has what too

Question 18

what is IAP?

Answer 18

bind to activated caspase to block them when they are spontaneously activated, inhibitors of apoptosis

Question 19

what is anti-IAP?

Answer 19

gets released with cytochrome c to inhibit IAP to allow for apoptosis

Question 20

how do you regulate apoptosis?

Answer 20

1. increased production of anti-apopototic bcl2 family protein
2. inactivation of pro-apoptotic BH3-only protein
3. inactivation of anti-IAPs

Question 21

how does increased production of anti-apopototic bcl2 family protein help regulate apoptosis?

Answer 21

survival factor and receptor activates transcription regulator to produce Bcl2 protein to block apoptosis

Question 22

how does inactivation of pro-apoptotic BH3-only protein block apoptosis?

Answer 22

survival factor binds to receptor which activates Akt kinase to take away Bcl2 inhibitor (Bad, BH3 only) through phosphorylation

Question 23

how does inactivation of anti-IAPs regulate apoptosis?

Answer 23

survival factor and receptor activates map kinase to phosphorylate Hid to inactive it. active Hid will inhibit IAPs.