Q.40 Match the chemical (Column I) with its use (Column II).
Column I Column II
P. Diethylpyrocarbonate 1. Chelation of magnesium ion during DNA purification
Q. Cesium chloride 2. Prevention of RNA degradation in aqueous environment
R. Ethidium bromide 3. Separation of DNA by density gradient centrifugation
S. Ethylenediaminetetraacetic acid 4. Staining of RNA in agarose gel
(A) P-4; Q-1; R-3; S-2
(B) P-4; Q-3; R-2; S-1
(C) P-2; Q-1; R-4; S-3
(D) P-2; Q-3; R-4; S-1
Diethylpyrocarbonate (DEPC), Cesium chloride (CsCl), Ethidium bromide (EtBr), and EDTA play key roles in nucleic acid handling. The correct matching identifies their standard lab applications.
Correct Answer
Option (D) P-2; Q-3; R-4; S-1 is correct.
Matches Explained
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P. Diethylpyrocarbonate → 2. Prevention of RNA degradation: DEPC inactivates RNases by carbethoxylation, ensuring RNase-free solutions for RNA work.
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Q. Cesium chloride → 3. Separation of DNA by density gradient centrifugation: CsCl forms equilibrium gradients under ultracentrifugation, separating DNA by buoyant density, as in Meselson-Stahl experiments.
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R. Ethidium bromide → 4. Staining of RNA in agarose gel: EtBr intercalates nucleic acids, fluorescing under UV to visualize both DNA and RNA bands.
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S. Ethylenediaminetetraacetic acid → 1. Chelation of magnesium ion during DNA purification: EDTA chelates Mg²⁺, inhibiting nucleases and stabilizing DNA extracts.
Option Analysis
| Option | P Match | Q Match | R Match | S Match | Status |
|---|---|---|---|---|---|
| (A) | 4 (Wrong: RNA staining) | 1 (Wrong: Mg chelation) | 3 (Wrong: centrifugation) | 2 (Wrong: RNase inhibition) | Incorrect |
| (B) | 4 (Wrong) | 3 (Correct) | 2 (Wrong: RNA protection) | 1 (Correct) | Incorrect |
| (C) | 2 (Correct) | 1 (Wrong) | 4 (Correct) | 3 (Wrong) | Incorrect |
| (D) | 2 (Correct) | 3 (Correct) | 4 (Correct) | 1 (Correct) | Correct |
