Question

there are three genes A B C percentage of crossing over between a and b is 20 % B and C is 28 % and C and a is 8 % then what is the sequence of genes on chromosome
A) b,a,c
B)a,b,c
C)a,c,b
D none of these

Answer 1

there are genes that means dna found in chromosomes in a nucleus of a cell

Answer 2

Heya..!


option A) b a c will be the correct order.


reason: among the genes located on a same chromosome, the recomobination% is directly proportional to distance beteen the genes.

if two genes are closely located, then recombination % will be less if they are distantly located, then recombination % will be more.

steps how to slove such type of questions:

step-1)Among the given recombination% values in the question, identify the highest recombination % and the genes .
example: in given question, 28% is the recombination between B & C genes. so, first write B and C with some distance between them.

step-2 ) observe the second highest recombination % and arrange that accordingly.

example: A & B genes have 20% recombination
now, two ways are possible.

A gene can be towards left to gene B or towards right.

to find out correct place, observe the recombination% among A & C
it's just 8% . so, genes A & C should be closely placed. so, position of Gene A should be in between B & C.



REFER TO THE IMAGE ATTACHED.


HOPE THIS HELPS YOU.


BE BRAINLY.