Question Details

Apoptotic bodies can be recognized with the presence of these on the surface

Options

A

phosphatidyl tyrosine

B

phosphatidylinositol

C

phosphatidylcholine

D

phosphatidylserine

Correct Answer :

phosphatidylserine

Solution :

The correct option is phosphatidylserine.

Apoptosis, or programmed cell death, is characterized by distinct morphological and biochemical changes. One key biochemical event during apoptosis is the alteration of the plasma membrane structure. In healthy cells, phospholipids are distributed asymmetrically between the inner and outer leaflets of the plasma membrane lipid bilayer.

Specifically, the phospholipid phosphatidylserine (PS) is actively maintained exclusively on the inner (cytoplasmic) leaflet of the plasma membrane by the action of ATP-dependent enzymes called flippases.
During apoptosis, this membrane asymmetry is lost. The enzyme flippase is inactivated, and scramblase enzymes are activated, which rapidly randomize the distribution of lipids across both leaflets. This results in the translocation (or "flip-flop") of phosphatidylserine to the outer (extracellular) leaflet of the plasma membrane.

The exposure of phosphatidylserine on the outer surface of apoptotic cells and apoptotic bodies serves as an essential "eat-me" signal. Phagocytic cells (such as macrophages) possess specific receptors that recognize extracellular phosphatidylserine. This recognition triggers the prompt engulfment and clearance of the apoptotic bodies, preventing tissue inflammation and damage that would otherwise occur if cell contents leaked out.

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