Question

QUESTION 9 What is the map distance between lys and val? Tetrad A Tetrad B Tetrad Tetrad D Tetrad e Tetrad F lys + lys + lys val lys val lys val + val lys + lys val lys val lys + + val lys + + val + + + + + + lys + + val + val + val + + + val + + lys + | 36 12 376 81 + + + + + +1 OOOO 13.5 the loci are not linked

Answer 1

Tetrad analysis is used to determine the distance between the centromere and the gene or the distance between gene and gene.unordered tetrad is of 3 types - parenatl ditype(PD), non parental ditype (NPD) and tetra type(TT).

here tetrad c is the Parental di type.( there is no crossing over)

Tetrad A and Tetrad F are NPD ( 100% recombinant)

Tetrad B, D, E are tetra type ( 50% recombinant 50% parental)

Here the number has been given for every tetrad.

when the distance between gene is calculated , PD and NPD are considered.

if NPD=PD (approximately )genes are not linked, they are independently assorted. Here PD is 37 and NPD is 36+1= 37.

So, here the loci are not linked.