Question

Select the correct sequence of morphological changes occurring in Apoptosis
A. Membrane blebbing
B. Phagocytosis
C. Nuclear fragmentation
D. Apoptotic bodies

• A. A, B, C, D
• B. D, C, A, B
• C. A, C, D, B
• D. D, A, C, B

Hint:

Chronological steps of Apoptosis:
1. Membrane Blebbing $\to$ 2. Nuclear Fragmentation $\to$ 3. Apoptotic Bodies formation $\to$ 4. Phagotic clearance (Phagocytosis).

Answer 1

The Correct Option is C

Step 1: Understanding the Question:
The question asks for the correct temporal order of morphological and cellular events taking place during programmed cell death (apoptosis).

Step 2: Key Formula or Approach:
Apoptosis follows a strictly regulated, orderly sequence of morphological transformations that prevents release of intracellular contents and inflammatory responses:
Membrane Blebbing (A) $\rightarrow{}$ Nuclear Fragmentation (C) $\rightarrow{}$ Formation of Apoptotic Bodies (D) $\rightarrow{}$ Phagocytosis (B)

Step 3: Detailed Explation:

• 1. Cell Shrinkage and Membrane Blebbing (A): Early in apoptosis, executioner caspases cleave cytoskeletal proteins, leading to cell shrinkage and dymic cell membrane bulging known as membrane blebbing.

• 2. Nuclear Condensation and Fragmentation (C): Pyknosis (chromatin condensation) is followed by karyorrhexis, where endonuclease activation (CAD) fragments nuclear chromatin into nucleosomal units.

• 3. Formation of Apoptotic Bodies (D): The dying cell pinches off into multiple membrane-bound vesicles containing cytosol, organelles, and nuclear fragments, termed apoptotic bodies.

• 4. Phagocytosis (B): Apoptotic bodies display "eat-me" sigls (such as exterlized phosphatidylserine) on their surface and are rapidly recognized and engulfed by phagocytes (macrophages) without inducing inflammation.

Step 4: Fil Answer:
The correct sequential order of apoptotic morphological events is A, C, D, B.