Apoptosis

Question 1

Advantages to mass cell death

Answer 1

1. Tissue homeostasis
2. Tissue development
3. Elimination of pathogen infected cells
4. Remove injured cells

Question 2

what are two ways cells die

Answer 2

gene independent (murder) or gene dependent (regulated cell death)

Question 3

what are two gene-dependent classes of cell death

Answer 3

1. Developmental/evolutionarily selected

2. Accidental (druggable)

Question 4

2 general cell death morphologies

Answer 4

apoptosis, necrosis

Question 5

3 molecularly defined pathways

Answer 5

apoptosis, necroptosis, and pyroptosis

Question 6

how do caspases kill by apoptosis

Answer 6

have hundreds of protein substrates it chops up, caspase-3 activates other caspases and packages cell corpse for engulfment

Question 7

Four steps in apoptotic death pathways

Answer 7

1. Decision to die
2. Execution : first pro-apoptotic gene is a protease Caspase 3
3. Engulfment
4. Degradation

Question 8

BAX/BID role in cell death

Answer 8

Has BH3 motif that binds and inhibits BCL-2, leading to cell survival - tumor cells often “addicted” to BCL-2

Question 9

Things to look for with apoptosis detection assays (4)

Answer 9

1. Cytochrome C release
2. Nuclear condensation
3. phosphatidylserine (eat me signal) on cell surface
4. Propidium iodide permeable, indicating “leaky” cell

Question 10

How do cells die by necroptosis

Answer 10

RIPK dependent, stimulated by pathogens or tissue injury, phosphorylates MLKL which oligomerizes and leads to Rupture/Death

Question 11

How do cells die by pyroptosis

Answer 11

Inflammasomes activated by pathogens or damage, form mega complex that activates Caspase-1, which then causes Gasermin D to oligomerize and rupture