GATE 2021 BT – Question 22

Genetics, Cellular and Molecular Biology · Cell Biology: Post-translational modifications, protein trafficking, cell death and autophagy, extracellular matrix · 1 mark · Multiple choice

The process supplying intracellular macromolecules for lysosomal degradation during nutrient starvation is

apoptosis
autophagy
phagocytosis
pinocytosis

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Correct answer: (B) autophagy

Explanation

During starvation a cell has to recycle its own material for energy.

**Autophagy** does this: a double-membrane vesicle (the **autophagosome**) engulfs cytoplasmic components such as proteins and damaged organelles, and fuses with a **lysosome**, where the contents are degraded and the building blocks reused.

**Apoptosis:** programmed cell death.
**Phagocytosis:** engulfing large **external** particles.
**Pinocytosis:** taking up external fluid in small vesicles.

Only autophagy supplies **intracellular** macromolecules to the lysosome. Answer **B**.