Question

Percentage of recombinant between A and B is 9%, A and C is 17%, B and C is 26%, then the arrangement of genesis
(A) ABC
(B) ACB
(C) BCA
(D) BAC

Answer 1

Hint: Since recombination frequency is directly proportional to the space between genes and the genes are located on a chromosome. Here, three genes A, B, and C can assume any of three linear sequences.

Complete answer:
In modern genetic analysis, the best test for determining whether two genes are linked is predicated on the concept of recombination. Recombination is observed during a sort of situation but, for this, let’s define it as meiosis. Meiotic recombination is any meiotic process that generates a haploid product with a genotype that differs from both haploid genotypes that constituted the meiotic diploid cell. the merchandise of meiosis so generated is named a recombinant. For genes corresponding on an equivalent chromosome pair, the physical connection of parental allele combinations makes dominant assortment difficult and therefore produces recombinant frequencies significantly less than 50 percent. Recombination frequency for A and B (X) is equal to 9%, that for A and C (Y) is equal to 17% and for B and C (Z) is equal to 26%.
As we will see that Z is equal to X + Y or 26 equal to 17 + 9 which suggests that genes B and C are present at extremes and A is within the middle. Thus, the sequence of genes is B-A-C.
Thus, the correct option is Option D - BAC

Note: One map unit or centimorgan is like the tenth recombination between the two genes. The frequency of recombination is often wont to depict the arrangement of the genes. By using the three possibilities of their arrangements A-B C, A -C-B, and B- A-C, it had been found that the three genes must be arranged within the order B-A-C with the expanse between B -A being 9 cand A-C being 17 cm and accordingly the distance between B-C being 26 cm.