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GENETICS Please Help! The answers have been provided under the questions but I r

ID: 168049 • Letter: G

Question

GENETICS Please Help! The answers have been provided under the questions but I really need to see the work/explanation for each as I do not understand. Thank you very much!!

94. What is the genotype of the females that gave rise to these progeny?   
px sp cn+/px+ sp+ cn

95. Using the two point cross method, what are the distances between these three genes?   
px-sp = .2 m.u., px-cn = 30 m.u., cn-sp = 30.2 m.u.

96. Using the three point cross method, determine which gene is in the middle (which has to be flipped).   
px.

Females heterozygous for the recessive second chromosome mutations pn, px, and sp are mated to a male homozygous for all three mutations. The offspring are as follows: px sp cn 1,461 px sp 3,497 px 11 sp cn 9 sp 0 cn 3,482 539 10000

Explanation / Answer

Answer:

94). px sp +/ + + cn

95).

sp-px = 0.21 mu

px-cn = 30.06 mu

sp-cn= 30.2 mu

96). The middle gene is px

Explanation:

Imagine the order is px sp + / + + cn

1. If single cross over (SCO) occurs between px & sp

Normal order= px --------- sp & + ----- +

After cross over= px-----+ & +------sp

px-----+ recombinants are 1+11= 12

+------sp recombinants are 9 +0 = 9

Total recombinants = 21

RF = (21/10000)*100 =0.21%

2. If single cross over (SCO) occurs between sp & +

Normal order= sp --------- + & + ------ cn

After cross over= sp ----- cn & +------ +

sp ----- cn recombinants are 1461 + 9 = 1470

+------ + recombinants are 1539 + 11= 1550

Total recombinants = 3020

RF = (3020/4197)*100 = 30.2%

3. If single cross over (SCO) occurs between px & cn

Normal order= px-------- + & +------ cn

After cross over= px-----cn & +------+

px-----cn recombinants are 1461+1= 1467

+------+ recombinants are 1539+0= 1539

Total recombinants = 3006

RF = (3006/4197)*100 = 30.06%

% RF = Map unit distance

The order of genes is -----

sp----0.21 m.u.---px----------30.06 m.u.------------cn