Question #54544

A test cross of F1 flies +a/+b produced the following offspring :
++/ab = 9
ab/ab = 9
+b/ab = 41
+a/ab = 41
What will be the distance between the linked genes and how?
(1) 82 cM
(2) 18 cM (cis)
(3) 20 cM
(4) 18 cM (trans)

Expert's answer

P: +a//+b X ab//ab

Organism +a//+b produces the following types of gametes:

Normal gametes: +a/, +b/

Gametes after crossover: ++/, ab/

Organism ab//ab produces the following types of gametes: ab/

G: +a/, +b/, ++/, ab/ X ab/

F1: +a//ab, +b//ab, ++//ab, ab//ab

Results:

++/ab = 9

ab/ab = 9

+b/ab = 41

+a/ab = 41

According to the results the crossover percentage – 18% (9+9).

The distance between the linked genes – 18 cM

Answer: (4) 18 cM (trans)

Organism +a//+b produces the following types of gametes:

Normal gametes: +a/, +b/

Gametes after crossover: ++/, ab/

Organism ab//ab produces the following types of gametes: ab/

G: +a/, +b/, ++/, ab/ X ab/

F1: +a//ab, +b//ab, ++//ab, ab//ab

Results:

++/ab = 9

ab/ab = 9

+b/ab = 41

+a/ab = 41

According to the results the crossover percentage – 18% (9+9).

The distance between the linked genes – 18 cM

Answer: (4) 18 cM (trans)

## Comments

Assignment Expert27.11.17, 17:15Dear visitor,

please use panel for submitting new questions

Unnathi26.11.17, 13:40why is it trans and not cis

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