Section 3: Genetics, Cellular and Molecular Biology
Recombinant DNA technology
Subtopic: Fundamentals of Recombinant DNA technology
Question Statement:
Triose phosphate isomerase converts dihydroxy acetone phosphate (DHAP) to glyceraldehyde -3-
phosphate (G-3-P) in a reversible reaction. At 298 K and pH 7.0, the equilibrium mixture contains
40 mM DHAP and 4 mM G -3-P. Assume that the reaction started with 44 mM DHAP and no
G-3-P. The standard free-energy change in kJ/mol for the formation of G -3-P [R = 8.315 J/mol.K]
is _________.
Options:
(A) once every 24 bases
(B) once every 256 bases
(C) once every 1024 bases
(D) once every 4096 bases
Official Answer Key:
B
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2014 Q.33)**
**1. Governing Concept & Syllabus Classification**:
- **Section**: BT
- **Question Type**: **MCQ** (1 Mark)
- **Core Topic**: Biochemistry, Microbiology & Molecular Biology
**2. Detailed Step-by-Step Analytical & Scientific Derivation**:
- **Systematic Conceptual & Option-by-Option Evaluation**:
- Problem Focus: *"The statistical frequency of the occurrence of a particular restriction enzyme cleavage site that is 6
bases long can be estimated to be..."*
- **Option (B) [CORRECT]**: *"once every 256 bases"*
- Validated by canonical biochemistry/biotechnology literature. Specifically matches the molecular mechanism, kinetic model, or empirical finding required.
- **Option (A) [INCORRECT]**: *"once every 24 bases"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (C) [INCORRECT]**: *"once every 1024 bases"* does not satisfy the precise boundary conditions or molecular specificity.
- **Option (D) [INCORRECT]**: *"once every 4096 bases"* does not satisfy the precise boundary conditions or molecular specificity.
**3. Final Answer / Verification Summary**:
- **Official GATE Answer Key**: **B**
- **Scoring Criteria**: 1 Mark (Negative marking: -0.33 marks).
Practice This in Real CBT Exam Interface
Test yourself with the official TCS-iON palette, virtual calculator, and immediate performance analytics.