Cell Death

Question 1

Necrosis vs Apoptosis

Answer 1

Necrosis - involves a cellular response to injury that causes local inflammation and the bursting of the cell (pathological)
Apoptosis - cellular response to cellular stresses that cause the shrinkage of the cell to be taken up by phagocytes (physiological)

Question 2

Six mechanisms of cell injury that would lead to cell death

Answer 2

ATP depletion, mitochondrial damage, accumulation of reactive oxygen species, influx of calcium, increased permeability of cellular membranes, accumulation of damaged DNA/misfolded proteins

Question 3

Intrinsic pathway of apoptosis

Answer 3

DNA damaged, lack of O2 or other stress, increases mitochondrial permeability via Bcl2 effector activation. Cytochrome C is released to trigger activation of APAF-1 and initiator caspase 9. APAF-1 forms the apoptosome and pro-caspase 9 binds to this and autoactivates. Caspase 9 cleaves and activates caspase 3,6,7 (executioner caspases) and leads to cell death

Question 4

Death receptors

Answer 4

Contain cytoplasmic death domain

Question 5

Bcl family

Answer 5

Proteins that interact with the mitochondrial membrane and each other

Question 6

Three types of Bcl-2 family proteins

Answer 6

Regulators, effectors, and sensors

Question 7

Regulator Bcl-2 proteins

Answer 7

Bcl-2 or Bcl-X, maintain mitochondrial membrane permeability, anti-apoptotic

Question 8

Effector Bcl-2 proteins

Answer 8

Bax or Bak, also known as BH123 proteins, form pores in the mitochondrial outer membrane, pro-apoptotic

Question 9

Sensor Bcl-2 proteins

Answer 9

Bad, Bid, Bim, Puma, Noxa, also called BH3-only proteins, inhibit Bcl-2 and activate effectors, pro-apoptotic

Question 10

Adaptors

Answer 10

APAF-1 (intrinsic) and FADD (extrinsic) both are pro-apoptotic

Question 11

Caspases

Answer 11

Proteases that degrade cellular components

Question 12

DNases

Answer 12

Digest genome

Question 13

IAPs

Answer 13

Inhibitors of apoptosis

Question 14

Anti-IAPs

Answer 14

Anti-inhibitors of apoptosis

Question 15

Initiator caspases

Answer 15

Activate themselves and then activate effector or executioner caspases to start a signal cascade

Question 16

Cellular stress (intrinsic)

Answer 16

Triggers activation of p53 or BH3-only proteins

Question 17

p53 (intrinsic)

Answer 17

Triggers the activation of BH3-only proteins

Question 18

BH3-only proteins

Answer 18

Inhibit Bcl-2 and activate BH123 proteins

Question 19

Bcl-2

Answer 19

Inhibits BH123 proteins from continuing apoptosis

Question 20

BH123 proteins

Answer 20

Activate anti-IAPs and trigger release of cytochrome c

Question 21

Cytochrome c

Answer 21

Activates APAF-1

Question 22

APAF-1

Answer 22

Activates caspase 9

Question 23

Caspase 9

Answer 23

Activate Caspases 3, 6, and 7

Question 24

Caspases 3, 6, 7

Answer 24

Activate various death substrates

Question 25

Extrinsic pathway of apoptosis

Answer 25

Cell surface death receptor is bound by TNF family ligand, receptors cluster and bind FADD, pro-caspase 8 or 10 bind FADD and autoactivate. Caspase 8 or 10 cleave executioner caspases to cause cell death

Question 26

Apoptosome

Answer 26

Made up of cytochrome c, APAF-1 and caspase 9

Question 27

DISC

Answer 27

Death receptor, FADD, and caspase 8 or 10

Question 28

Cellular stress (extrinsic)

Answer 28

Triggers activation of p53

Question 29

p53 (extrinsic)

Answer 29

Activates death receptor/ligand complex

Question 30

FADD

Answer 30

Activates caspases 8/10

Question 31

Caspases 8/10

Answer 31

Activate caspases 3, 6, and 7

Question 32

Apoptosis and health

Answer 32

Apoptosis is normal and helps maintain cellular functions. Any disorder in apoptosis will lead to cancer or other diseases.

Question 33

Other types of cell death

Answer 33

Necroptosis, pyroptosis, and autophagy