Problem

Solutions For An Introduction to Genetic Analysis Chapter 4 Problem 33P

Step-by-Step Solution

Solution 1

A plant with homozygous (hyg/hyg. her/her) was crossed with wild type (hyg⁺/ hyg⁺. her⁺/ her⁺). The resultant F₁ (filial generation-1) progeny would be heterozygous (hyg⁺/ hyg. her⁺/ her). The selfing of F₁ yields following progeny:

Therefore, 56.25% of seeds have neither drug, or nor herbicide resistance, 18.75% of seeds have only herbicide resistance, 18.75% of seeds have only drug resistance, and 6.25% of seeds have both drug and herbicide resistance.

Step #2 of 5

If two genes are unlinked, and they are placed on the medium containing hygromycin and herbicide, then only 6.25% of progeny were expected to grow. This is because only one out of 16 seeds would have shown drug and herbicide resistance.

Thus, the answer is

Step #3 of 5

Under normal circumstances (unlinked) only 6.25% of seeds are expected to grow, but in the given condition 13% of seeds grew. This is a double amount than the normal expected range. So, assume that the genes are linked, and then the cross would be as follows:

From the obtained results, 13% of seeds have both drug and herbicide resistance (hyg/hyg. her/her). Therefore, yes the percentage support the hypothesis of no linkage. This class represents a combination of two parental chromosomes, which is equal to

Step #4 of 5

Where,

• = 0.72

So,

The frequency of recombinants is about 1-0.72 = 0.28. Thus, the gene distance between hyg/her is

Step #5 of 5

A test cross is defined as a crossing between an organism, which is heterozygous for one or more genes, and an organism, which is homozygous for the recessive alleles. The test cross of F₁ is as follows: