PCD

Question 1

PCD v Necrosis

Answer 1

PCD: mediated, controlled, regulated, cell suicide. Orderly controlled dissolution of cell components
Necrosis: forced, accidental, no control

Question 2

Morphological changes during apoptosis

Answer 2

Cell shrinks
Membrane blebs
Pyknosis
Karyorrhexis

Question 3

Morphological changes during necrosis

Answer 3

Cell swells
Membrane Ruptures 
Pyknosis
Karyorrhexis
Karyolysis

Question 4

Apoptotic process v necrotic process

Answer 4

A: programmed, caspase signalling, non-lytic, non-inflam

N: accidental, non-caspase, lytic, inflam

Question 5

Physiological apoptosis processes

Answer 5

Sculpting stuctures (lose interdigital webbing)
Deletion of structures (larva-adult fly/ persistant mullerian duct syndrome)
Regulating cell no. (Embryo neurones & oocytes, hormone resp eg prostate/mammary)

Question 6

Disease causes of apoptosis

Answer 6

Cancer

Pathogen infection

Question 7

What is a caspase

Answer 7

Enzymes (proteases)
Synthesised as inactive pro-caspase then (auto)cleaved just after aspartate residue.
Form cascades activating next in line
Can also be involved in inflam and differentiation
Initiator and executioner

Question 8

Initiator caspase

Answer 8

Inactive monomer - dimerise - active dimer
8&9, have 3 domains
Can self cleave
Found early in pathway- needed to activate executioner caspase
V specific (only a few substrates)
Can self cleave

Question 9

Executioner caspase

Answer 9

3&7
Inactive dimer - active dimer via active initiator caspase
2 domains
Occur downstream from initiator
Less specific (many substrates) cause cellular changes seen in apoptosis

Question 10

Intrinsic pathway

Answer 10

Dna damage - BAK/BAX activation - act on mitochondria - cause MOMP - cytochrome c leak out - bind APAF1 - bind procaspase 9 (in apoptosome) - activate caspase 3&7 - cause apoptosis

Question 11

Extrinsic pathway

Answer 11

Signal eg necrosis factor - activate death rec - activate caspase 8 (can x talk and affect BAK & BAX) - activate caspase 3&7 - cause apoptosis

Question 12

Engulfment process

Answer 12

Sensing of apoptotic cell (find me)
Recognition of ap cell (eat me)
Internalisation of ap cell
Digestion of ap cell

Question 13

Which cells carry out engulfment

Answer 13

Macrophages or dendritic cells

Question 14

Describe the eat me signal

Answer 14

Phosphatidylserine externalisation

A phospholipid normally found on the inner leaflet that is flipped due to an apoptotic signal

Question 15

Antiapoptotic proteins

Answer 15

AA BCL-2 proteins

Inhibitors of apoptosis proteins (IAPs)

Question 16

AA BCL-2 fx

Answer 16

Interfere with BAK/BAX activation

Question 17

IAP fx

Answer 17

Interfere with caspase 3&7 activation

Interfere with procaspase 9 activation to caspase 9 amd so apoptosome formation

Question 18

Cellular changes during apoptosis

Answer 18

Caspase activation and protein cleavage
Phosphatidylserine externalisation
Chromosome DNA cleavage into internucleosomal fragments

Question 19

Factors promoting apoptosis inhibition

Answer 19

GFs
Androgens
Some viral pros

Question 20

How does Vaccinia virus inhibit apoptosis

Answer 20

Pros N1 and F1 have similar structure to AA BCL-2 so bind BAX and BAK so prevent them from altering the MOMP so prevent apoptosis

Question 21

How does African Swine Fever prevent apoptosis

Answer 21

Pro A24L is similar to cellular IAP pros so binds casp 3 and so prevent apoptosis

Question 22

Describe autophagy

Answer 22

PCD type in response to lack of nutrients or damaged cell components (eg misfolded pro response)
Recycles its own organelles and macromolecules by forming autophagosomes. Creates vacuolated cytoplasm. Reversible up to a point
Can occur in the same cell at the same time as apoptosis and is a back up cell death method

Question 23

Describe pyroptosis

Answer 23

Uses casp 1 
Inflammatory and lytic
Mechanism of overcoming IC survival by some pathogens
Chromatin condense but no karyorrhexis
Half way between apoptosis and necrosis

Question 24

Cells that carry out pyroptosis

Answer 24

Only macrophages and dendritic cells

Question 25

Describe entosis

Answer 25

Cell cannibalism
Neughbouring cells eat cells (mostly at epi membrane) that have detached from the ECM - often occurs in cancer
No casp act or phosphotidylserine (diff eat me signal) so not apoptosis

Question 26

Possible entosis purposes

Answer 26

Anti-cancer mech

Way to recycle nutrients