In a population of 1000 individuals , 500 individuals have Aa genotype and 500 have AA genotype. What will be the proportion of a and A alleles in their gametes ?

Options

A. `1:1`
B. `1:2`
C. `1:3`
D. `3:1`

Answer

To solve the question regarding the proportion of alleles in the gametes of a population with 1000 individuals, where 500 individuals have the Aa genotype and 500 have the AA genotype, we can follow these steps:

### Step 1: Identify the Genotypes and Their Frequencies
- In the population, we have:
- 500 individuals with the Aa genotype (heterozygous)
- 500 individuals with the AA genotype (homozygous dominant)

### Step 2: Determine the Gametes Produced by Each Genotype
- The Aa individuals can produce two types of gametes:
- 50% will carry the A allele
- 50% will carry the a allele
- The AA individuals can produce only one type of gamete:
- 100% will carry the A allele

### Step 3: Calculate the Total Gametes Produced
- Total gametes from Aa individuals:
- 500 Aa individuals × 2 gametes each = 1000 gametes
- Out of these, 500 will be A and 500 will be a.

- Total gametes from AA individuals:
- 500 AA individuals × 1 gamete each = 500 gametes
- All of these will be A.

### Step 4: Sum Up the Total Gametes
- Total A gametes:
- From Aa: 500 A
- From AA: 500 A
- Total A = 500 + 500 = 1000 A gametes

- Total a gametes:
- From Aa: 500 a
- From AA: 0 a
- Total a = 500 + 0 = 500 a gametes

### Step 5: Calculate the Proportions of Each Allele
- Total gametes produced = 1000 (from Aa) + 500 (from AA) = 1500 gametes
- Proportion of A alleles = Total A gametes / Total gametes = 1000 / 1500 = 2/3
- Proportion of a alleles = Total a gametes / Total gametes = 500 / 1500 = 1/3

### Step 6: Express the Proportions as a Ratio
- The ratio of allele a to allele A is:
- a : A = 1/3 : 2/3 = 1 : 2

### Final Answer
The proportion of allele a to allele A in their gametes is 1:2.

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