In a cross between an individual who is RrPp and one who is rrpp, the following
ID: 318369 • Letter: I
Question
In a cross between an individual who is RrPp and one who is rrpp, the following offspring are obtained: 27 RrPp 21 rrrp 25 Rrpp 20 Rrpp a) Are the R and P genes linked to each other? How do you know? b) Are the R and P genes on the same chromosome as each other? In a series of crosses to look at the relationship of different genes with each other, the following crosses were performed. The numbers of offspring obtained from each cross are shown. a) For each one. note whether the genes are linked, and if so how closely (in mu); and whether the alleles are present in coupling or repulsion in the heterozygous parent. b) Which genes are most tightly linked (closest together on the same chromosome)?Explanation / Answer
3. a) As the genotypes are showing 1:1:1:1 ratio, those are not linked genes.
For further conformation adopting chisquare test
Null hypothesis: The observed values are not deviating form the Expected 1:1:1:1 ratio.
Category
RrPp
rrpp
Rrpp
rrPp
Total
Observed values
27
21
25
20
93
Exptected Ratio
1
1
1
1
4
Exprected Values
23.25
23.25
23.25
23.25
Deviation
3.75
-2.25
1.75
-3.25
D^2
14.0625
5.0625
3.0625
10.5625
D^2/E
0.604839
0.217742
0.13172
0.454301
1.408602
X^2
1.408602
Degrees of freedom
4-1
3
Inference: The calculated chi square value is lessthan the table value @ 3 DF and 0.05 probability i.e. 7.815, Hence null hypothesis accepted.
b) As the genes are showing independent assortment, which means both genes are present on same chromosome.
According to chegg guidelines we have to answer one question at a time, so post the other question as sperate question then I can help you.
Category
RrPp
rrpp
Rrpp
rrPp
Total
Observed values
27
21
25
20
93
Exptected Ratio
1
1
1
1
4
Exprected Values
23.25
23.25
23.25
23.25
Deviation
3.75
-2.25
1.75
-3.25
D^2
14.0625
5.0625
3.0625
10.5625
D^2/E
0.604839
0.217742
0.13172
0.454301
1.408602
X^2
1.408602
Degrees of freedom
4-1
3