In an experiment, while screening for loss-of-function mutants, a student found a mutation in the gene encoding caspase-9 in the intrinsic pathway of apoptosis. The following are the possible consequences for this mutant cell:

A. Loss of mitochondrial membrane potential and release of cytochrome C.
B. Reduced formation of the apoptosome and defective initiation of apoptosis.
C. Inability to activate the death receptors.
D. Become resistant to UV irradiation-induced cell death.

Which one of the following options represents all correct statements?

Correct option is C

EXPLANATION-

A. Loss of mitochondrial membrane potential and release of cytochrome C.
This is incorrect – This occurs upstream of caspase-9 activation. A mutation in caspase-9 would not prevent loss of mitochondrial potential or cytochrome c release.

B. Reduced formation of the apoptosome and defective initiation of apoptosis.
This is correct– Caspase-9 is crucial for apoptosome formation; a loss-of-function mutation will impair this process.

C. Inability to activate the death receptors.
This is incorrect – Death receptors are part of the extrinsic pathway (involving caspase-8), not affected by caspase-9 mutation.

D. Become resistant to UV irradiation-induced cell death.
This is correct– UV damage often triggers the intrinsic pathway, so a caspase-9 mutant may resist this kind of apoptosis.

So, the correct option is (c)  B and D only