Question

Absence of trophic factors causes caspase activation. The non-phosphorylation of Bad protein causes ions to enter mitochondria and Cyt C to exit. Cyt C + Apaf1 --> procaspase 9 --> caspase 9 --> procaspase 3 --> caspase 3 --> cleavage of substrates, cell death.

Answer 1

The discussion focuses on apoptosis, a programmed cell death mechanism involving cytochrome C release from mitochondria, leading to caspase activation and cell death.

Step-by-step explanation:

The process being described in the question is apoptosis, which is programmed cell death essential for the removal of damaged, superfluous, or potentially dangerous cells in an organism. The initial signal for apoptosis can be the absence of trophic factors leading to caspase activation. Cytochrome C (Cyt C) plays a critical role when it exits the mitochondria and, along with Apaf1, helps convert procaspase 9 into caspase 9, which subsequently activates caspase 3 through procaspase 3. This leads to the cleavage of cellular substrates, culminating in cell death. Key proteins involved in this process include Bad, which when not phosphorylated, allows ions to enter mitochondria; and Bcl2 proteins Bak and Bax, which are involved in the release of Cyt C. Moreover, external signaling, such as from the extracellular matrix or due to viral infection, can also initiate apoptosis.