Week 5 Holy - Cell Death

Question 1

What are the three types of cell death discussed in class?

Answer 1

1. Necrosis
2. Apoptosis
3. Autophagy

Question 2

What are the distinct morphological changes in the cell during Apoptosis?

Answer 2

1. Condensation of chromatin
2. Plasma membrane exhibits blebbing
3. Entire cell shrinks
4. Nucleus becomes fragmented

Question 3

How does the apoptotic cell trigger phagocytosis?

Answer 3

• Changes in the plasma membrane
  
  • phosphatidylserines are flipped out
    
    • signals macrophages
• Acidification of the cytoplasm
• Nuclear destruction

Question 4

True/False: Inflammation reactions occur in apoptosis.

Answer 4

FALSE!

Inflammation reactions do NOT occur in apoptosis!

(they can in necrosis)

Question 5

Proteases that are responsible for the destruction of the cell during apoptosis are called what?

Answer 5

CASPASES!

(named due to their function: cysteine-aspartic acid proteases)

Question 6

How do caspaces become activated?

Answer 6

• Initiator caspaces associate with DISC
• Active initiator caspaces activate effector caspases
• Caspases dimerization
• Proteolytic cleavage
• Activate themselves & others!
  
  • Caspace cascade

Question 7

What events trigger the extrinsic apoptotic pathway?

Answer 7

Signaling events at the cell surface/plasma membrane.

Death Receptors… Mwuhahaha

Ligands, Receptors, Caspase activation

Question 8

What events trigger the intrinsic apoptotic pathway?

Answer 8

• Involves damage or stress
  
  • transmitted to mitochondria → outer membrane pore opening (MOMP
  • release of cytochrome C
  • form APOPTOSOME (cyt C + APAF-1 + caspase 9)
• Caspase-8 from the Extrinsic pathway can also transmit to the mito to release cyt C

Question 9

What are the two functional groups (kinds) of caspaces?

Answer 9

1. Initiator caspases
2. Effector caspases

Question 10

What are three ligands involved in the extrinsic pathway of apoptosis?

Answer 10

1. TNF family of cytokines (tumor regression and septic shock)
2. FAS ligand
3. TRAIL (TNF-related apoptosis-inducing ligand)

*ligands are either membrane-associated proteins that are anchored to the membrane or released

*usually form trimers

Question 11

What are the three types of receoptors involved in the extrinsic pathway of apoptosis?

Answer 11

1. TNF-receptor family
2. FAS receptor
3. TRAIL receptor

*ALL are integral membrane proteins

Question 12

How is the DISC (death-inducing signaling complex) formed from the recptors of the extrinsic pathway of apoptosis?

Answer 12

• Receptors trimerize during ligand binding
• recruit adaptor proteins with death domains
• form scaffold = DISC (death-inducing signaling complex)
  
  • which binds and activates initiator caspases