Apoptosis involves all but which of the following?
(A) fragmentation of the DNA
(B) cell-signaling pathways
(C) lysis of the cell
(D) digestion of cellular contents by scavenger cells
The Correct Answer and Explanation is :
Correct Answer:
(C) Lysis of the cell
Explanation:
Apoptosis, or programmed cell death, is a tightly regulated process that allows cells to self-destruct in a controlled manner, maintaining homeostasis and preventing damage to surrounding tissues. It is distinct from necrosis, which is a form of uncontrolled cell death often resulting from injury or infection.
- Fragmentation of DNA (Option A) – During apoptosis, specific enzymes called caspases activate endonucleases, which fragment chromosomal DNA into smaller pieces. This step is essential for dismantling the cell in an orderly manner and preventing damage to neighboring cells.
- Cell-signaling pathways (Option B) – Apoptosis is regulated by intricate signaling pathways, including intrinsic (mitochondrial) and extrinsic (death receptor) pathways. The intrinsic pathway is triggered by cellular stress or DNA damage, leading to mitochondrial outer membrane permeabilization and cytochrome c release. The extrinsic pathway involves external signals binding to death receptors on the cell membrane, initiating apoptosis.
- Lysis of the cell (Option C) – Incorrect – Unlike necrosis, apoptosis does not involve the lysis (bursting) of the cell. Instead, apoptotic cells undergo controlled shrinkage, membrane blebbing, and fragmentation into apoptotic bodies. These bodies are then engulfed by phagocytes, preventing inflammation.
- Digestion of cellular contents by scavenger cells (Option D) – Once apoptotic bodies form, they are swiftly recognized and engulfed by scavenger cells such as macrophages. This prevents the release of intracellular contents, ensuring a clean and non-inflammatory process.
Thus, the correct answer is (C) Lysis of the cell, as apoptosis avoids cell rupture to prevent inflammation and tissue damage. Instead, it ensures the safe removal of dying cells through phagocytosis.
Now, I’ll generate an image representing the apoptosis process.
Here is an educational illustration depicting the apoptosis process, including key stages such as membrane blebbing, DNA fragmentation, and phagocytosis by scavenger cells. Let me know if you need any modifications or further explanations!