Download sex-linked problems

Name _____________________________
Genetics: X Linked Genes
In fruit flies, eye color is a sex linked trait. Red is dominant to white.
1. What are the sexes and eye colors of flies with the following genotypes:
XRXr
_________________
X R Y _________________
R
R
X X
_________________
X r Y _________________
2. What are the genotypes of these flies:
white eyed, male ____________
white eyed, female ___________
red eyed female (heterozygous) ________
red eyed, male ___________
3. Show the cross of a white eyed female X r X r with a red-eyed male X R Y .
4. Show a cross between a pure red eyed female and a white eyed male.
What are the genotypes of the parents: ___________ x _______________
How many are:
white eyed, male_______
white eyed, female ______
red eyed, male ________
red eyed, female ________
5. Show the cross of a red eyed female (heterozygous) and a red eyed male.
What are the genotypes of the parents? ____________ & ________________
How many are:
white eyed, male______
white eyed, female ______
red eyed, male _______
red eyed, female _______
Hemophilia is a rare inherited bleeding disorder where the blood does not clot normally. Someone with
hemophilia may bleed for a longer time following an injury.
H = no hemophilia (normal)
h = hemophilia (x linked recessive trait)
Fill in the following phenotypes:
XHXH = __________________
XHXh = __________________
XhXh = __________________
XHY = __________________
XhY = __________________
6. In humans, hemophilia is a sex linked trait. Show the cross of a man who has hemophilia with a
woman who is a carrier.
What is the probability that their children will have the disease? __________
7. A woman who is a carrier marries a normal man. Show the cross. What is the probability that their
children will have hemophilia? What sex will a child in the family with hemophilia be?
8. A woman who has hemophilia has a phenotypically normal mother. What are the genotypes of her
mother and father?
Mom _______________________
Dad _______________________
9. A phenotypically normal woman has phenotypically normal parents. However, she has a hemophiliac
brother. a) What are the chances of being a carrier for hemophilia? ____________________
Color blindness (color vision deficiency) is a condition in which certain colors cannot be distinguished,
and is most commonly due to an inherited condition. Red/Green color blindness is the most common
form, about 99% of all color blind cases, and causes problems in distinguishing reds and greens. Another
color deficiency Blue/Yellow also exists, but is rare. Total color blindness (seeing in only shades of gray)
is extremely rare.
C = normal vision
c = color blind
10. If a normal sighted woman whose father was colorblind marries a color blind man, what is the
probability that they will have a son who is colorblind? ______________________
b) What is the probability that they will have a color blind daughter? ________________
11. What is the probability that a color blind woman who marries a man with normal vision will have a
color blind child?
In cats, the calico color pattern has black, orange/red, and white all represented in clear color blocks. The
gene for calico (multicolored) cats is codominant. Females that receive a B (Black) and an O (Orange)
gene have black and orange splotches on white coats. Males can only be black or orange, but never
calico.
Fill out the phenotypes for the following genotypes:
XBXB = ___________________
XBXO = ___________________
XOXO = ___________________
XBY = ___________________
XOY = ___________________
12. Show the cross of a female calico cat with a black male?
What percentage are black male kittens? _________
What percentage are calico female kittens? _________
13. Show the cross of a female black cat, with a male orange cat.
What percentage are calico female? _______
What color will all the male kittens be? ______