Subtopic: Fundamentals of Downstream processing (chromatography, filtration)
Question Statement:
Which of the following types of molecules act as biological catalysts?
[P] Protein
[Q] RNA
[R] Phospholipid
Options:
(A) P and Q only
(B) P and R only
(C) Q and R only
(D) P, Q and R
Official Answer Key:
A
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2020 Q.22)**
**1. Governing Concept**:
- **Topic**: Biochemistry & Biological Catalysts
- Evaluating biomolecules as catalysts:
- **[P] Proteins**: The vast majority of biological enzymes are proteins (e.g., polymerases, kinases, proteases) $\rightarrow$ **CATALYST**.
- **[Q] RNA**: Catalytic RNA molecules (**ribozymes**, e.g., the 23S/28S rRNA peptidyl transferase center of ribosomes, self-splicing group I/II introns, RNase P) act as true biological catalysts $\rightarrow$ **CATALYST**.
- **[R] Phospholipids**: Structural lipids of biological membranes; do not possess macromolecular catalytic activity $\rightarrow$ **NOT A CATALYST**.
- Therefore, only **P and Q** act as biological catalysts.
**2. Option Analysis**:
- **Option (A) [P and Q only] is CORRECT**: Proteins and RNA (ribozymes) are the two bona fide classes of biological catalysts.
- **Option (B) is INCORRECT**: Phospholipids are structural, not catalytic.
- **Option (C) is INCORRECT**: Excludes protein enzymes.
- **Option (D) is INCORRECT**: Includes phospholipids.
**3. Final Answer**:
- **Correct Choice**: **A**
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