Question

Genetics problem: I am looking for help with (e) but I have provided (d) for the added input it has on the problem set. Thank you to whomever is able to answer the problem.

(d) (2 pts) F' merodiploid strains are constructed for the region of the chromosome that includes the histidine biosynthetic operon. Below are the results of pairwise complementation tests: a"+" indicates growth without added histidine: F' His Donor His mutant# 10 4. 2 his Growth on minimal medium without added histidine Recipient Mutant # 1 4 10 Based on these results, how many genes seem to be involved in the biosynthesis of histidine (a minimal estimate)? (e) (9 pts) What can you say about mutant #10 Give me two different mutant types that account for the results presented for mutant 10. Tell me whether each type is dominant or recessive and whether it acts in cis or trans.

Answer 1

d) It is clear that there are minimal 8 genes involved in the biosynthesis of histidine.

Cross between recepient 1 and donor 2 shows the mutation is present on different gene can complement growth of the diploid strain represent gene1. Explaining on same line gene 2 ( cross among recepient 1 and donor 3). Gene 4( Cross among recepient 1 and donor 4). Gene 5 ( cross among recepient 1 and donor 5). Gene 5 ( cross among recepient 1 and donor 6). Gene 6 (cross among recepient 1 and donor 7). Gene 7 (cross among recepient 1 and donor 8). Gene 8 (cross among recepient 1 and donor 9).

e) Mutant 10 has mutation on same gene hence it does not complement with either recepient mutant 1,2,3,4,5,6,7,8 and thereby do not grow on minimal essential media without histidine.

Mutant 10 crossed with any recepient mutant do not complement, it states that they exhibit two recessive mutation on same gene that thereby is His mutant and do not grow on minimal media without histidine.

These mutations are on same gene hence it acts in cis form.