Question

Complete the following question by providing detailed explanations with examples.

What is apoptosis? Explain cell signaling pathways that triggers it.

Answer 1

Apoptosis is the programmed cell death.

It is controlled and regulated by the rate of cell division; when the cell is not needed, pathway of cell death is activated.

Signaling pathways:

The triggering factors act at the cell membrane, either intracellularly or extracellularly. These include:

I) transmembranois- withdrawal of signals required for normal cell survival (eg. Absence of certain hormones, growth factors, cytokines?

2) extracellularly triggering factors. Eg. Activation of FASS receptor belonging to TNF-R family)

3) intracellular stimuli include heat, radiation, hypoxia etc.

Process:

Activation of caspases➡️ activation of death receptors ➡️ activation of growth controlling gene ➡️ cell death

Phagocytosis

In this membrane changes (eg. Expression of phosphatidylserine, thrombospondin)

There are no inflammatory cells present.