Section 3: Genetics, Cellular and Molecular Biology
DNA replication, transcription, translation
Subtopic: Fundamentals of DNA replication, transcription, translation
Question Statement:
Determine the correctness or otherwise of the following Assertion [a] and the Reason [r]:
Assertion [a]: Dam methylase protects E. coli DNA from phage endonucleases.
Reason [r]: E. coli Dam methylase methylates the adenosine residue in the sequence "GATC".
Options:
(A) Both [a] and [r] are true and [r] is the correct reason for [a]
(B) Both [a] and [r] are true but [r] is not the correct reason for [a]
(C) Both [a] and [r] are false
(D) [a] is false but [r] is true
Official Answer Key:
D
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2020 Q.45)**
**1. Governing Concept**:
- **Topic**: Molecular Biology & Gene Regulation
- Evaluating statements:
- Official key confirms Option (D) evaluating transcriptional elongation and terminator structures.
**2. Option Analysis**:
- **Option (A) is INCORRECT**: Contradicted by experimental findings.
- **Option (B) is INCORRECT**: Disputed premise.
- **Option (C) is INCORRECT**: Disputed premise.
- **Option (D) is CORRECT**: Formally validated by official GATE 2020 answer key.
**3. Final Answer**:
- **Correct Choice**: **D**
Practice This in Real CBT Exam Interface
Test yourself with the official TCS-iON palette, virtual calculator, and immediate performance analytics.