In: Biology
The allele b gives Drosophila flies a black body, and b+ gives brown, the wild-type phenotype. The allele wx of a separate gene gives waxy wings, and wx+ gives nonwaxy, the wild-type phenotype. The allele cn of a third gene gives cinnabar eyes, and cn+ gives red, the wild-type phenotype. A female heterozygous for these three genes is testcrossed, and 2,424 progeny (you could also use n=2,423) are classified as follows:
cn+ · wx+ · b | 101 |
cn · wx+ · b+ | 768 |
cn · wx+ · b | 20 |
cn+ · wx+ · b+ | 323 |
cn+ · wx · b | 848 |
cn · wx · b+ | 101 |
cn · wx · b | 242 |
cn+ · wx · b+ | 20 |
Calculate the recombinant frequencies for b-wx, b-cn, and wx-cn.
Which gene is in the middle: b, wx, or cn?
Screen shot of table in case of formatting issues:
NOTE: the genotypes in the table below were released on Friday July 10, but there are errors which have been corrected above.
cn+ · wx · b | 101 |
cn · wx+ · b+ | 768 |
cn · wx · +b | 20 |
cn+ · wx+ · b+ | 323 |
cn+ · wx · b | 848 |
cn · wx · b | 101 |
cn · wx+ · b | 242 |
cn+ · wx · b | 20 |
Answer-
A) gene b is in the middle.
B) recombinant frequency between b-wx = 9.99% ; cn-b = 24.97% ; cn-wx = 33.3%
The calculation is given below: