Question

A female fruit fly with vermilion eyes and normal wings is crossed to a male with normal red eyes and cut wings. The F1 progeny consist of females with red eyes and normal wings, and males with vermilion eyes and normal wings. When the F1 progeny are interbred, the F2 consists of two types of females vermilion eyes, normal wings (1/2) and red eyes, normal wings (12), and two types of males-vermilion eyes, normal wings (12) and red eyes, cut wings (12). Are the genes for eye color and wing type X-linked or autosomal? Multiple Choice The eye-color gene is X-linked and the wing-type gene is autosomal The eye-color gene is autosomal and the wing-type gene is linked Both genes are xnked Oo ooc Both genes are autosomal More than one of the choices is consistent with the data

Answer 1

We have been given that,

Female = Vermilion eye color and normal wing

Male = Normal Red eye and cut wing

F1 progenies are :

female = Red eye and normal wing

Male = Vermilion eye and normal wing

F2 progenies are :

Female = 1/2 vermilion eye and normal wing

1/2 Red eye and normal wing

Male = 1/2 vermilion eye and normal wing

1/2 Red eye and cut wings.

As we analyse the pattern in F2 only males get cut wings on crossing F1. So,this means the gene for wings is in X-chromosome.

In F1 progenies femlaes are red eyes and males are Vermilion from the parents in which female have Vermilion eye and male had normal Red eye. This means the gene is X-linked.

Answer is both genes are X-linked, option C.

Red is Dominant = R

Vermilion is recessive = r

Normal wing = dominant = N

Cut wing is recessive = n

P1 = Vermilion eye and normal wing female = XrN XrN

Normal Red eye and cut wing male = XRn Y

	XrN	XrN
XRn	XRn XrN	XRn XrN
Y	XrN Y	XrN Y

F1 progenies are :

Females = Red eye and Normal wings

Males = Vermilion eye and Normal wings

When F1 are crossed = Red eye and Normal wing female X Vermilion eye and Normal wing

XRn XrN X XrN Y

	XRn	XrN
XrN	XRn XrN	XrN XrN
Y	XRn Y	XrN Y

F2 progenies are

Femlaes = 1/2 -- XRn XrN = Red eye normal wings

= 1/2 ---- XrN XrN = Vermilion eye normal wings

Males = 1/2 ---- XRn Y = Red eye and cut wings

= 1/2 ---- XrN Y = Vermilion eye and Normal wings

So,both genes are X-linked.

Thank you...

Expect a ???