QuestionSBA
QuestionChoice
Cytochrome C molecules released by the MOMP activate APAF1 which associates with pro-caspase 9 to form the apoptosome. Pro-caspase 9 is then cleaved, activating its own protease activity. Caspase 9 cleaves effector caspases 3 and 7 which activate apoptotic enzymes such as caspase-dependent DNase.
10001121
a
Pro-caspase 9 is cleaved
QuestionChoice
Cytochrome C molecules released by the MOMP activate APAF1 which associates with pro-caspase 9 to form the apoptosome. Pro-caspase 9 is then cleaved, activating its protease activity. Caspase 9 cleaves effector caspases 3 and 7 which activate apoptotic enzymes such as caspase-dependent DNase.
10001124
d
Released cytochrome C inhibits APAF1
QuestionChoice
BH3-only is a protein activated by p53 after DNA damage or endoplasmic reticulum stress. It activates BAX/BAK which oligomerises in the mitochondrial outer membrane to form a pore through which factors including cytochrome C can be released to cause apoptosis. This action is therefore upstream of the MOMP.

<br>
10001125
e
BH3-only activates BAX/BAK
QuestionChoice
XIAP is an inhibitor of apoptosis that is constitutively active in cells and inhibits the activity of caspase 9 in the apoptosome and effector caspases 3 and 7 to prevent the inappropriate activation of apoptosis. XIAP levels decrease upon apoptotic signalling. In type 1 cells (mostly immune cells), this is initiated by the activation of death receptors without the need for a MOMP. In type 2 cells (most other cells), this is mediated by MOMP release of SMAC which inhibits XIAP.
10001123
c
XIAP levels rise
QuestionChoice
Caspase 8 is an initiator caspase which is activated by proximity to other caspase 8 molecules. This occurs upon trimeric death receptor activation by extracellular ligands, resulting in the recruitment of FADD to the cytoplasmic components which in turn recruits caspase 8. Caspase 8 can then cleave effector caspases 3/7 or cleave BID to tBID to activate BAX/BAK formation of the MOMP. This action is therefore upstream of the MOMP.
10001122
b
Caspase 8 activation
Concept
Chapter
2693
3886
Apoptosis
Topic
181
Structure and Function of Cells
12771
The formation of the mitochondrial outer membrane pore (MOMP) leads to which of the following events?
a