The following X-linked traits are found in fruit flies: vermilion eyes are reces
ID: 217374 • Letter: T
Question
The following X-linked traits are found in fruit flies: vermilion eyes are recessive to red eyes, miniature wings are recessive to long wings, and sable body is recessive to gray body. A cross was made between wild-type males with red eyes, long wings, and gray bodies to females with vermilion eyes, miniature wings, and sable bodies The heterozygous females from this cross, which had red eyes, long wings, and gray bodies, were then crossed to males with vermilion eyes, miniature wings, and sable bodies. The following outcome was obtained: Males and Females 1320 vermilion eyes, miniature wings, sable body 1346 red eyes, long wings, gray body 102 vermilion eyes, miniature wings, gray body 90 red eyes, long wings, sable body 42 vermilion eyes, long wings, gray body 48 red eyes, miniature wings, sable body 2 vermilion eyes, long wings, sable body 1 red eyes, miniature wings, gray body Calculate the map distance between the three genes.Explanation / Answer
Answer
According to the question, it is a trihybrid cross
Then,
cross RRLLGG X rrllgg
gametes RLG rlg
F1 RrLlGg
Let us suppose F1 individual is Female
So,
RrLlGg X rrllgg
Gametes RLG RLg RlG Rlg rLG rLg rlG rlg X rlg
Genotype F1 RrLlGg, RrLlgg, RrllGg, Rrllgg, rrLlGg, rrLlgg, rrllGg, rrllgg
F2 genotype ration 27:9:9:9:3:3:3:1
From the genotype construction, we have seen that max are a parental type.
From the outcome of a result, maximum individuals are parental types.
It is defined that map distance between genes is equaled to the percentage crossing over frequency.
From the given data
The distance between R------L
No of an individual of Single crossover + No of individual of a double crossover X 100
Total no of individual
= 42+48+2+1 X 100
2951
=3.15cM
The distance between R------g
= No of an individual of Single crossover + No of individual of a double crossover X 100
Total no of individual
= 102+90+2+1 X 100
2951
= 6.6cM
Map is R-----------L-------------g