In a Drosophila, three recessive mutations can lead to white eyes, yellow body and vestigial wings. A heterozygous fly is crossed with a fly recessive for all these mutations. Using the following data, the distance between the gene for wing shape and eye color would be ________cM. (Answer upto one point after decimal)Correct answer is between '17.1,17.5'. Can you explain this answer?

Question

Answer

q² = 0.04. Then, q = 0.2. p = 1-q = 0.8.
Frequency of heterozygotes will be 2pq = 2(0.8)(0.2) = 0.32

The gene w is in the middle. Distance between vg and w will be = Number of SCOs (79+84) + number of DCOs(8) / 1000 = 17.1 cM

Answer

q² = 0.04. Then, q = 0.2. p = 1-q = 0.8.
Frequency of heterozygotes will be 2pq = 2(0.8)(0.2) = 0.32

The gene w is in the middle. Distance between vg and w will be = Number of SCOs (79+84) + number of DCOs(8) / 1000 = 17.1 cM

Answer

To determine the distance between the gene for wing shape and eye color in Drosophila, we can use the data from the cross between a heterozygous fly (XWXwY) and a fly recessive for all three mutations (XwXwY). Here, X represents the wild-type allele, w represents the recessive allele for white eyes, and Y represents the wild-type allele for body color.

First, let's analyze the phenotypes of the offspring resulting from this cross:

- XWXwY: Wild-type eye color, yellow body, wild-type wings
- XwXwY: White eyes, yellow body, vestigial wings

Based on these phenotypes, we can deduce the genotype of the heterozygous fly:

- XWXwY: This fly must have one wild-type allele for eye color (X) and one recessive allele for wing shape (w).

Now, let's cross the heterozygous fly (XWXwY) with a fly recessive for all three mutations (XwXwY) and analyze the phenotypes of the offspring:

- XWXwY (heterozygous) x XwXwY (recessive): The possible genotypes and phenotypes of the offspring are as follows:
- XwXwY: White eyes, yellow body, vestigial wings
- XWXwY: Wild-type eye color, yellow body, wild-type wings

To determine the distance between the gene for wing shape (w) and eye color (X), we can use the formula:

Recombination frequency (RF) = (number of recombinant offspring / total number of offspring) * 100

In this case, the recombinant offspring are those that have a different combination of traits compared to the parental genotypes:

- XwXwY: White eyes, yellow body, vestigial wings
- XWXwY: Wild-type eye color, yellow body, wild-type wings

Next, we need to count the number of recombinant and non-recombinant offspring:

- Total number of offspring = Number of XwXwY + Number of XWXwY
- Number of recombinant offspring = Number of XwXwY

Using the given data, we can calculate the recombination frequency:

RF = (Number of XwXwY / Total number of offspring) * 100

Since the answer is given in centimorgans (cM), we can assume that one map unit is equal to one percent recombination frequency. Therefore, the distance between the gene for wing shape and eye color would be equal to the recombination frequency.

Now, let's calculate the recombination frequency using the data provided.

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