Download X n Y

*Sex influenced traits
*The gene is NOT on a sex
chromosome, but SEX
affects the phenotype
*Example-baldnessdominant in males,
recessive in women
*If ‘B’ represents bald
and ‘b’ is hairy then
Men must be bb to keep
hair
Women can be Bb or BB
to keep hair
*Caused by a gene that
is located on a SEX
chromosome (X or Y)
*Most sex-linked traits
are found on the X
chromosome
*Is the pedigree beside
this like MOST sexlinked traits?
*
*Most are recessive
*Examples-hemophilia,
red-green colorblindness
*Males are more likely to
have these because they
cannot be carriers
*Why?
*Males are XY-if their ‘X’
has a bad gene, there is
nothing on the ‘Y’ to
dominate over it
*
*N
n
* XNXN=Normal
* XNXn=CARRIER, but IS NOT
colorblind
* XNY=Normal
* XnY=HAS red-green
colorblindess
*
*Carrier mom XNXn
*Normal Dad XNY
XN
Xn
XN
XN XN
X N Xn
Y
XNY
XnY
*
*
*Orange and Black Alleles
are on the X chromosome
in cats
*White is on another
chromosome (autosome).
*Result-some cells make
black fur, some orange
*
*Polygenic-more than one pair of alleles determines
phenotype--eye color
*Female genotype?
*Male genotype?
*What percent of
possible offspring are
female?
*What percent of
possible offspring are
male?
*
What is the genotype of a
woman who is a carrier of
hemophilia?
What is the genotype of a
man who does not have
hemophilia?
Will any of their children
potentially have hemophilia?
What sex will the child have
to be?
Last vocabulary term of
importance.
Purebred – Always breeds true to
dominant trait. i.e. homozygous
dominant individual