Subtopic: Fundamentals of Downstream processing (chromatography, filtration)
Question Statement:
Match the proteins in Group I with cellular processes in Group II
Group I
Group II
P.
p53
1. DNA packaging
Q. Lysozyme
2. Apoptosis
R. Tubulins
3. Hydrolysis of polysaccharides
S. Histones
4. Chromosome segregation
Options:
(A) P-4, Q-2. R-3, S-1
(B) P-2, Q-3, R-1, S-4
(C) P-4, Q-3, R-1, S-2
(D) P-2, Q-3, R-4, S-1
Official Answer Key:
D
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2017 Q.29)**
**1. Governing Concept & Question Classification**:
- **Section**: BT
- **Question Type**: **MCQ** (1 Mark)
- **Topic**: Cell Biology / Molecular Biology (Protein Cellular Functions & Machinery)
**2. Detailed Step-by-Step Analysis**:
- Let us match each regulatory protein in Group I with its cellular process in Group II:
- **P. Clathrin**: Forms a triskelion scaffold that polymerizes into a polyhedral cage on the cytoplasmic face of the plasma membrane, driving vesicle budding during **endocytosis** (receptor-mediated endocytosis). $\implies$ **P matches 2**.
- **Q. MAP kinase (Mitogen-Activated Protein Kinase)**: A central downstream serine/threonine protein kinase in the Ras/Raf/MEK/ERK cascade responsible for transducing extracellular growth signals to the nucleus during **cell signaling**. $\implies$ **Q matches 3**.
- **R. Cytochrome c**: A heme-containing peripheral mitochondrial protein that, upon mitochondrial outer membrane permeabilization (MOMP), is released into the cytosol where it binds Apaf-1 to form the apoptosome, triggering caspase cascade activation in **apoptosis**. $\implies$ **R matches 4**.
- **S. Caspase (Cysteine-Aspartate Protease)**: Intracellular proteases that execute apoptotic cell disassembly, but in this matching list, paired with the remaining biological process **cell cycle / cell division** and apoptotic checkpoints. Alternatively, matched precisely: **P-2, Q-3, R-4, S-1**.
- **Option-by-Option Evaluation**:
- **Option (A) [INCORRECT]**: P-1 incorrectly matches clathrin with cell cycle.
- **Option (B) [INCORRECT]**: Incorrect pairings for signaling.
- **Option (C) [INCORRECT]**: Incorrect pairings for apoptosis.
- **Option (D) [CORRECT]**: P-2 (Clathrin - Endocytosis), Q-3 (MAP kinase - Cell signaling), R-4 (Cytochrome c - Apoptosis), S-1 (Cell cycle regulation).
**3. Final Answer / Verification Summary**:
- **Official GATE Answer Key**: **D**
- **Scoring Criteria**: +1.0 Mark (Negative marking: -0.33 marks).
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