Everwin Matric. Hr. Sec. School

09.09.19 Bio-Botany Material Std: XII

Ch-3 Chromosomal Basis of Inheritance

1. Determine the sequence of genes along a chromosome

based on the following recombination frequencies.

AB=8 map units AC=28 map units

AD=25 map units BC=20 map units

BD=33 map units

Order of the gene is C B A D

D A B C

2. If parent recombination between AB 5% BC 3% A&C 8%

what is the order of the gene?

Single cross over

+ + + wild

x

p q r Recessive

↓

+ q r Last 2 gene swapping

P + + (RP)

Single cross over

+ + +

x

p q r

↓

+ + r Swapping in last gene

P q + (RP)

Double cross over + + +

x x p q r Swapping in centre ↓ + q + Recombinant products P + r