Download Sex Linked Inheritance Worksheet

SEX-LINKED INHERITANCE
 This is a form of inheritance where the gene/allele for the characteristic being
studied is on the
chromosome.
 Diseases such as color-blindness and hemophilia are inherited this way, and are
more common in
than females.
HEMOPHILIA
 Alleles, Genotypes and Phenotypes for Hemophilia (Blood-Clotting Inability)
XH – allele for normal blood clotting
Xh – allele for hemophilia
XHXH – genotype of normal female
XhXh – genotype of hemophiliac female
XHXh – genotype of carrier female (with normal blood-clotting ability, but who can
pass the gene to her children)
XHY – genotype of normal male
XhY – genotype of hemophiliac male
 Example 1 – Hemophilia
A man with normal blood-clotting ability (XHY) marries a woman who is a
hemophiliac (XhXh). The possible phenotypes of their children are...
XH
Y
Xh
Xh
Possible genotypes = __________________________________
Possible phenotypes=
________________________________
 Example 2 – Hemophilia
A normal woman (XHXH) marries a hemophiliac man (XhY). The possible genotypes
and phenotypes of the children are...
XH
XH
Xh
Y
Possible genotypes = ____________________________________
Possible phenotypes=
______________________________
RED-GREEN COLOR BLINDNESS
 Alleles, Genotypes and Phenotypes for Color-blindness
XB - allele for normal color vision
Xb - allele for color-blindness
XBXB - genotype of normal female
XbXb - genotype of color-blind female
XBXb - genotype of carrier female (with normal colour vision, but who can pass the
defective gene to her children)
XBY - genotype of normal male
XbY - genotype of color-blind male
 Example 3 – Color Blindness
A male with normal vision (XBY) and a colorblind female (XbXb) have children. The
possible genotypes and phenotypes of the children are ...
XB
Y
Xb
Xb
Possible genotypes =
Possible phenotypes =
 Example 4 – Color Blindness
A carrier female (XBXb ) marries a normal-visioned male (XBY). The possible
genotypes and phenotypes of the children are...
XB
XB
Y
Possible genotypes=
Possible phenotypes=
Xb