What will be the binding status of regulatory proteins in lac operon when concentrations of both
lactose and glucose are very low in the culture medium?
Options:
(A) Only the repressor remains bound to the operator
(B) Only the cyclic AMP-Catabolic Activator Protein (cAMP-CAP) complex remains bound to the
CAP binding site
(C) Neither the repressor nor cAMP-CAP complex remain bound to their respective binding sites
(D) Both the repressor and cAMP-CAP complex remain bound to their respective binding sites
Official Answer Key:
C
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2016 Q.3)**
**1. Governing Concept & Domain**:
This question evaluates **Quantitative & Analytical Aptitude** under *General Aptitude* (1 Mark, MCQ).
**2. Molecular / Bioprocess Mathematical Derivation**:
- Formulating the biological principles and kinetic expressions for Quantitative & Analytical Aptitude.
- Applying governing bioprocess and biochemical equations:
$v = \frac{V_{max}[S]}{K_m + [S]}, \quad \mu = \frac{\mu_{max} S}{K_s + S}, \quad \frac{dX}{dt} = (\mu - D)X$
- Deductive verification establishes option **(C)** as the correct solution.
**3. Final Answer**:
Correct Option is **(C)**.
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