An in vitro translation system can synthesize peptides in all three reading frames of the RNA
template. When 5' - UCUCUCUC--(UC)UCUCUCUC - 3' was used as the template in this in
vitro translation system, the synthesized peptides contained 50% each of serine and leucine. When
5' - CCUCCUCCU-(CCU)CCUCCU- 3' was used as the template, the synthesized peptides
contained 33.3% each of serine, leucine, and proline. Deduce the codon for proline.
Options:
(A) UCU
(B) CUC
(C) CCU
(D) UCC
Official Answer Key:
C
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2015 Q.58)**
**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: *"An in vitro translation system can synthesize peptides in all three reading frames of the RNA
template. When 5' - UCUCUCUC--(UC)UCUCUCUC - 3' was used as the template in this in
vitro translation system, the synthesized ..."*
- **Option (C) [CORRECT]**: *"CCU"*
- Validated by canonical biochemistry/biotechnology literature. Specifically matches the molecular mechanism, kinetic model, or empirical finding required.
- **Option (A) [INCORRECT]**: *"UCU"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (B) [INCORRECT]**: *"CUC"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (D) [INCORRECT]**: *"UCC
Options :
1. *
A
2. * B
3. 9 C
4. * D"* does not satisfy the precise boundary conditions or molecular specificity.
**3. Final Answer / Verification Summary**:
- **Official GATE Answer Key**: **C**
- **Scoring Criteria**: 2 Marks (Negative marking: -0.66 marks).
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