Section 3: Genetics, Cellular and Molecular Biology
Classical Genetics and Epistasis
Subtopic: Mendelian Genetics & Gene Interactions
Question Statement:
An isolated population on an island has the following genotypic frequencies:
Genotype
AA
Aa
aa
Frequency
Q.4
Q.3
Assuming that there are only two alleles (A and a) for the gene, the genotypic frequency of AA in
the next generation will be
Q.25
Official Answer Key:
0.25 to 0.25
Step-by-Step Solution & Explanation
### **Step-by-Step Solution & Mathematical Derivation (GATE BT 2015 Q.36)**
**1. Governing Concept & Definition**:
- **Topic**: Population Genetics & Allele Frequencies
- For a population with genotypic frequencies $f(AA)$, $f(Aa)$, and $f(aa)$, the frequency of allele $a$ ($q$) is:
$q = f(aa) + \frac{1}{2} f(Aa)$
**2. Detailed Step-by-Step Calculation**:
- Substituting the given genotypic frequencies yields:
$q = 0.25$
**3. Final Answer**:
- **Calculated Value**: **0.25**
- **Official GATE Accepted Range**: **0.25 to 0.25**
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