Question

1. In cats, two unlinked genes control coat coloration: D, an autosomal gene, causes fur to be black (D/-) or brown (d/d). Black is the wildtype and brown is caused by a mutation E, an X-linked gene, causes white fur and is dominantly epistatic to D. (Write as XE or Xe). A pure-breeding white male cat is mated with a pure-breeding brown female cat. A. What are the genotypes of the parents? what phenotypic ratio is expected in the F17(Rem ember that sex is included in phenotype.) B. what phenotypic ratio is expected in the F27(Remember that sex is included in phenotype.) C.

Answer 1

Answer:

A).

XEY ; DD = Pure breeding white male

XeXe; dd = Pure breeding brown female

b).

XEY; DD (male) x (female) XeXe; dd ------Parents

	Xe d
XE D	XEXe ; Dd (white female)
Y D	XeY; Dd (black male)

All daughters are white color and all sons are with black color

Expected phenotypic ratio = 1:1

c).

XEXe; Dd (female) x XeY; Dd (male)—F1xF1

	XeD	Xed	YD	Yd
XED	XEXe; DD (white)	XEXe; Dd (white)	XEY; DD (white)	XEY; Dd (white)
XEd	XEXe; Dd (white)	XEXe; dd (white)	XEY; Dd (white)	XEY; dd (white)
XeD	XeXe; DD (black)	XeXe; Dd (black)	XeY; DD (black)	XeY; Dd (black)
Xed	XeXe; Dd (black)	XeXe; dd (brown)	XeY; Dd (black)	XeY; dd (brown)
	Female		Male

Phenotypic ratio = Black : White : Brown = 6:8:2 = 3:4:1