What is apoptosis and how is it regulated?

Name: Problem 7, Chapter 22: Genetics: A Conceptual Approach
Uploaded: 2020-07-01T04:06:39-08:00
Duration: 25 s
Channel: Sam Limsuwannarot
Description: What is apoptosis and how is it regulated?

Key Concepts

Regulatory Proteins

Regulatory proteins, such as members of the Bcl-2 family, are critical in controlling the balance between cell survival and death. These proteins include both pro-apoptotic molecules (which promote apoptosis) and anti-apoptotic molecules (which inhibit apoptosis). Their interactions determine the cell's response to apoptotic signals by influencing mitochondrial membrane permeability and thus the activation of the intrinsic apoptotic pathway.

Apoptosis

Apoptosis is a form of programmed cell death that occurs in multicellular organisms. It is a tightly regulated process essential for development, tissue homeostasis, and the removal of defective or damaged cells. This process is characterized by distinct morphological and biochemical changes, such as cell shrinkage, chromatin condensation, DNA fragmentation, and the formation of apoptotic bodies which are ultimately cleared by phagocytic cells.

Intrinsic Apoptotic Pathway

The intrinsic pathway, also known as the mitochondrial pathway, is regulated by internal cellular signals. Stress factors such as DNA damage, oxidative stress, or other toxic insults lead to the modulation of mitochondrial membrane permeability. This results in the release of pro-apoptotic factors like cytochrome c, which then convene the assembly of the apoptosome complex, initiating the cascade of caspase activation that drives the apoptotic process.

Extrinsic Apoptotic Pathway

The extrinsic pathway is initiated by signals external to the cell. This pathway involves the binding of specific ligands to cell surface death receptors, which triggers a signaling cascade leading to the activation of initiator caspases. These caspases then propagate the signal by activating effector caspases that execute apoptosis by degrading key cellular components.

Caspases

Caspases are a family of protease enzymes that play a central role in the execution of apoptosis. They exist as inactive precursors (zymogens) and, upon receiving apoptotic signals through either the intrinsic or extrinsic pathways, become activated. Once active, caspases cleave various substrate proteins essential for cell survival and structural integrity, leading to systematic cellular dismantling.

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