Subtopic: Fundamentals of Downstream processing (chromatography, filtration)
Question Statement:
The process by which intracellular macromolecules are supplied for lysosomal
degradation during nutrient starvation is
Options:
(A) apoptosis
(B) autophagy
(C) phagocytosis
(D) pinocytosis
Official Answer Key:
B
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2021 Q.22)**
**1. Governing Concept**:
- **Topic**: Cell Biology & Intracellular Protein Degradation
- **Autophagy** ("self-eating") is the catabolic cellular process wherein damaged organelles and cytoplasmic macromolecules are sequestered into double-membrane vesicles (**autophagosomes**) that fuse with **lysosomes** for degradation, recycling nutrients and amino acids during nutrient starvation.
**2. Option Analysis**:
- **Option (A) [apoptosis] is INCORRECT**: Programmed cell death.
- **Option (B) [autophagy] is CORRECT**: The specific lysosomal degradation pathway activated by nutrient starvation.
- **Option (C) [phagocytosis] is INCORRECT**: Engulfment of large extracellular particles.
- **Option (D) [pinocytosis] is INCORRECT**: Non-specific fluid-phase endocytosis.
**3. Final Answer**:
- **Correct Choice**: **B**
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