Final answer:
The mitochondrial permeability during apoptosis is controlled by Bcl2 family proteins Bak and Bax by forming mitochondrial channels. Cytochrome C released into the cytoplasm activates a cascade leading to cell death.
Step-by-step explanation:
The permeability of the mitochondria during the intrinsic pathway of apoptosis is controlled by Bcl2 proteins Bak and Bax, which form channels in the outer mitochondrial membrane. When signaled, these channels allow the release of cytochrome C into the cytoplasm. Cytochrome C then interacts with adaptor proteins to form a complex that activates procaspases, leading to the caspase-mediated execution phase of apoptosis.
Under normal conditions, cytochrome C exists in a state of equilibrium, loosely bound to the inner mitochondrial membrane. Upon receiving apoptotic signals, conformational changes in Bcl2 proteins facilitate the opening of mitochondrial channels composed of Bak and Bax, thus determining the organelle's permeability. The mitochondrial (intrinsic) pathway of apoptosis is a crucial mechanism that enables damaged or unnecessary cells to undergo programmed cell death, maintaining cellular and organismal homeostasis.