GATE BT 2024 • Q50
MSQ • 2 Marks
Section 4: Bioprocess Engineering and Process Biotechnology
Downstream processing (chromatography, filtration)
Subtopic: Fundamentals of Downstream processing (chromatography, filtration)
Question Statement:
Which of the following statements regarding the below mentioned mRNA
sequence is/are TRUE?
5`-UGAUGAGCCUUAACCGGGAACGAAUUUAAG-3`
Options:
-
(A) It contains nine codons in the reading frame
-
(B) It contains ten codons in the reading frame
-
(C) It codes for eight amino acids
-
(D) It codes for nine amino acids
Step-by-Step Solution & Explanation
### **Official Solution & Concept Analysis (GATE BT 2024 Q.50)**
**1. Governing Concept**:
- **Topic**: Molecular Biology & Polycistronic vs. Monocistronic mRNA
- In prokaryotes, polycistronic mRNAs contain multiple Shine-Dalgarno (ribosome binding site) sequences and internal start/stop codons that allow independent internal translation initiation of distinct polypeptides.
- In eukaryotes, mRNAs are typically monocistronic, initiating translation via $5'$ 7-methylguanosine cap recognition and Kozak sequence scanning.
**2. Option Analysis**:
- **Option (A) is CORRECT**: The presence of multiple open reading frames with internal translation start codons allows synthesis of distinct functional proteins from a single polycistronic transcript.
- **Option (B) is INCORRECT**: Contradicts translation initiation principles.
- **Option (C) is CORRECT**: Internal stop codons demarcate the carboxyl-termini of upstream cistrons without prematurely aborting downstream translation.
- **Option (D) is INCORRECT**: Violates the genetic code triplet structure.
**3. Final Answer**:
- **Correct Options**: **A, C**
Practice This in Real CBT Exam Interface
Test yourself with the official TCS-iON palette, virtual calculator, and immediate performance analytics.
Launch CBT Mock Test