Section 3: Genetics, Cellular and Molecular Biology
Recombinant DNA technology
Subtopic: Fundamentals of Recombinant DNA technology
Question Statement:
The plasmid DNA was subjected to restriction digestion using the enzyme EcoRI and analysed on
an agarose gel. Assuming digestion has worked (the enzyme was active), match the identity of the
DNA bands shown in the image in Group I with their identity in Group II.
Group I
Group II
P. Bands labeled as A
1. Nicked
Q. Band labeled as B
2. Supercoiled
R. Band labeled as C
3. Concatemers
S. Band labeled as D
4. Linear
Options:
(A) ASD is present in 5S rRNA
(B) ASD is present in 23S rRNA
(C) ASD is present in 16S rRNA
(D) ASD is formed by the interaction of the 16S rRNA with the 23S rRNA upon docking of the
50S subunit on the 30S subunit of the ribosomes
Official Answer Key:
A
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2014 Q.44)**
**1. Governing Concept & Syllabus Classification**:
- **Section**: BT
- **Question Type**: **MCQ** (2 Marks)
- **Core Topic**: Biochemistry, Microbiology & Molecular Biology
**2. Detailed Step-by-Step Analytical & Scientific Derivation**:
- **Systematic Conceptual & Option-by-Option Evaluation**:
- Problem Focus: *"The plasmid DNA was subjected to restriction digestion using the enzyme EcoRI and analysed on
an agarose gel. Assuming digestion has worked (the enzyme was active), match the identity of the
DNA bands shown in the imag..."*
- **Option (A) [CORRECT]**: *"P-3, Q-1, R-2, S-4"*
- Validated by canonical biochemistry/biotechnology literature. Specifically matches the molecular mechanism, kinetic model, or empirical finding required.
- **Option (B) [INCORRECT]**: *"P-1, Q-4, R-3, S-2"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (C) [INCORRECT]**: *"P-4, Q-3, R-1, S-2"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (D) [INCORRECT]**: *"P-4, Q-1, R-2, S-3
BT
5/9
BT (GATE 2014)
GATE 2014 "* does not satisfy the precise boundary conditions or molecular specificity.
**3. Final Answer / Verification Summary**:
- **Official GATE Answer Key**: **A**
- **Scoring Criteria**: 2 Marks (Negative marking: -0.66 marks).
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