A particular gene B affects body weight in mice. In a randomly mating population
ID: 141061 • Letter: A
Question
A particular gene Baffects body weight in mice. In a randomly mating population, Bhas two alleles, designated B1andB2. The genotypes and body weights of a sample of 50 mice are shown on the following page, and are also posted in an Excel spreadsheet on Canvas.
1. Calculate the genotypic values for the three genotypes B1B1,B1B2, and B2B2.
Genotype
Avg. weight (g)
B1B1
B1B2
B2B2
1. Find the mid-homozygote value (m) and the values for a and d.
2. For values of p(i.e. the frequency of allele B1ranging from 0.1 to 0.9, in increments of 0.1, calculate each of the following: m, a1, a2,a(= a1- a2), breeding values for the three genotypes (A11,A12, and A22), and the additive, dominance, and total genetic variance. Prior to doing these calculations, rescale your genotypic values to set m= 0. Set this up in an Excel spreadsheet, with each of the inputs (a, d, and p) and all calculated values in separate columns. Put each value of pin a separate row. Then answer the following questions:
a. How would you describe the dominance relationship of B1to B2? (I.e. is the effect of B1dominant, partially dominant, completely additive, recessive, partially recessive, or overdominant?)
b. How does the value of achange as the frequency of B1changes?
c. At what frequency of B1is VAthe greatest? VD? VG?
d. Suppose B1is initially at low frequency (0.1) in the population, but the mice are selected for higher body weight over many generations. What will happen over time to the frequency of B1? What will happen to the breeding value of B1B2heterozygotes?
below is the data that need to solve above question and I WANT TO GET HELP OR GUIDE ON HOW TO DO THESE QUESTION IF ANY ONE KNOW:
Sample Genotype Weight
1 B1B1 113
2 B1B1 96
3 B1B1 109
4 B1B1 113
5 B1B1 114
6 B1B1 108
7 B1B1 112
8 B1B1 90
9 B1B1 106
10 B1B1 124
11 B1B1 103
12 B1B1 117
13 B1B1 119
14 B1B1 113
15 B1B1 113
16 B1B2 108
17 B1B2 118
18 B1B2 103
19 B1B2 112
20 B1B2 93
21 B1B2 110
22 B1B2 99
23 B1B2 101
24 B1B2 97
25 B1B2 106
26 B1B2 107
27 B1B2 110
28 B1B2 94
29 B1B2 118
30 B1B2 107
31 B1B2 108
32 B1B2 104
33 B1B2 110
34 B1B2 98
35 B1B2 96
36 B1B2 105
37 B1B2 109
38 B1B2 125
39 B2B2 79
40 B2B2 85
41 B2B2 98
42 B2B2 81
43 B2B2 97
44 B2B2 103
45 B2B2 90
46 B2B2 82
47 B2B2 84
48 B2B2 105
49 B2B2 84
50 B2B2 92
Genotype
Avg. weight (g)
B1B1
B1B2
B2B2
Explanation / Answer
1) calculate the genotypic values for three genotype B1B1 ,B1B2 and B2B2 is as follows :
Avg.B1B1 weight =113+96+109+113+114+108+112+90+106+124+103+117+119+113+113÷15
=110 g
Avg.B1ab2 weight =108+118+103+112+93+110+99+101+97+106+107+94+118+107+108+104+110+98+96+105+109+125÷23
=101.21 g
Avg.B2B2 weight =79+85+98+81+97+103+90+82+84+105+84+105+84+92÷12
=90 g
Here sum total weight of each type of genotype is divided by total number of each genotype . So we got a following answer for three type of genotype
Genotype . Avg.weight
B1B1. 110 g
B1B2. 101.21 g
B2B2 . 90 g
(1) Find the mid homozygote value (m) and values for a and d.
The mid point of the genotypic values between two homozygote is the zero point on the scale
Genotype A1A1 A1A2 A2A2
Genotypic a d 0 -a
Values
Frequencies p2 2pq q2
and is required to determine d. It is (2.66+1.48)/2=2.07
So value of (m) =2.07
The value of a is computed as
a=BB value -bb value /2
a =2.66-1.48/2
a =0.59
Thus the dominant derivation d is
d=Bb value -mid point
d =2.17-2.07
d =0.10
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