Question

In yeast, one haploid strain is unable to synthesize uracil but able to synthesize leucine, while

Answer 1

Answer:

The two genes are come from one chromosome.

Explanation:

a. One haploid can synthesize uracil, another one can synthesized leucine. Assume that there is not any mutation, two different amino acids should be encoded by different genes.

b. The genotypes of two haploid strains are different. Each has contained single chromosomes, as same as gametes in any Eukaryotic organism.

c. Firstly, yeast is an Eukaryotic organism, diploid. It means they have chromosomes in pair. Secondly, haploid cell contains half of the chromosomes from parent cell. Due to the theory of meiosis, the half chromosome encoding leucine go to one haploid cell, the other encoding uracil go to another haploid cell. If they are from different chromosomes, there is a chance to have a haploid which can produce both uracil and leucine. Thus, the only possible answer is that they are from a chromosome in opposite long-arm or short-arm of the chromosome, which is later divided into two haploid.

d. There is not any haploid strain which is able to produce both uracil and leucine.