Question

QUESTION 6 A bacterial strain with the genotype his leu* gal* strain was used as the donor to transform another strain with the genotype his leu gal. The genotypes of the transformed cells were as follows: I Number of cells 112 - 32 98 Genotype hist leut gat his leut gal hist leu galt hist leut galt his leu galt his leu gal his leut galt - 54 What is the order of the genes? Please explain your reasoning. Which two genes are closest to each other? How do you know?

Answer 1

A)The greater number of cross over tell that the genes are closer apart. And the less number are found. Now look in the table, his+ leu+ gal+ are lesser in number. It means there is found more cross over. This is possible only, when the his gene is in middle.

That's why order is leu his gal.

Look in image

neut his galt X X X X + teu hist gal lent hist galt 4 crossover required

B)

Now we have to find the genes which are closest.

The greatee cross over numbee is found, when genes are far apart

Whereas small number are found in the genes which are found to be closest.

deur hist galt - leu hist galt (54) It means leu and leu hist gal his are far apart reut his galt een histx gae- but his-gai-32:

That's why his and gal are closest to each other.