Section 3: Genetics, Cellular and Molecular Biology
Classical Genetics and Epistasis
Subtopic: Mendelian Genetics & Gene Interactions
Question Statement:
In a random mating population, Y and y are dominant and recessive
alleles, respectively. If the frequency of Y allele in both sperm and egg is
Q.70, then the frequency of Y/y heterozygotes (rounded off to two decimal
places) is
Official Answer Key:
0.41 - 0.43
Step-by-Step Solution & Explanation
### **Step-by-Step Solution & Mathematical Derivation (GATE BT 2021 Q.58)**
**1. Governing Concept & Definition**:
- **Topic**: Population Genetics & Hardy-Weinberg Equilibrium
- For a biallelic locus with alleles $Y$ (frequency $p$) and $y$ (frequency $q = 1 - p$):
- Frequency of heterozygotes ($Y/y$) $= 2pq$.
**2. Detailed Step-by-Step Calculation**:
- **Given**:
- Frequency of dominant allele $Y$: $p = 0.70$
- **Frequency of recessive allele $y$**:
$q = 1 - p = 1 - 0.70 = 0.30$
- **Heterozygote Frequency ($2pq$)**:
$2pq = 2 \times 0.70 \times 0.30 = 0.42$
**3. Final Answer**:
- **Calculated Value**: **0.42**
- **Official GATE Accepted Range**: **0.41 to 0.43**
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