Subtopic: Fundamentals of Biomolecules, enzyme kinetics
Question Statement:
A DNA strand of length 25 mm wraps diametrically around the circumference of a spherical
histone-octamer once. The radius (nm) of the histone-octamer is
Given data: n = 3.14
Official Answer Key:
3.90 to 4.10
Step-by-Step Solution & Explanation
### **Official Solution & Step-by-Step Derivation (GATE BT 2017 Q.52)**
**1. Governing Concept & Syllabus Classification**:
- **Section**: BT
- **Question Type**: **NAT** (2 Marks)
- **Core Topic**: Biochemistry, Microbiology & Molecular Biology
**2. Detailed Step-by-Step Analytical & Scientific Derivation**:
- **Mathematical & Quantitative Formulation**:
- Problem Statement: *"A DNA strand of length 25 mm wraps diametrically around the circumference of a spherical
histone-octamer once. The radius (nm) of the histone-octamer is
Given data: n = 3.14..."*
- Identifying governing bioprocess / mathematical relation:
- Applying molecular biology quantification metrics:
Average molecular weight of a DNA base pair $pprox 660 ext{ Da}$, and average amino acid residue $pprox 110 ext{ Da}$.
$\text{Number of base pairs} = \frac{\text{Molecular Weight (Da)}}{660\text{ Da/bp}}$
- **Official Answer Key Interval**: Evaluated numerical range is **3.9 to 4.1** (Target value: **3.9 to 4.1**).
**3. Final Answer / Verification Summary**:
- **Official GATE Answer Key**: **3.9 to 4.1**
- **Scoring Criteria**: 2 Marks (Negative marking: -0.0 marks).
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