Download Genetics Problems

Genetics Problems
Dominant/Recessive Type
• A Black fly is crossed with a
gray fly to produce offspring
of which 1/2 are black and
1/2 are gray. What are the
genotypes of the parents?
• In sesame plants, normal leaf is dominant
to wrinkled leaf. Determine the
genotypes for the two parents for
following offspring:
–
–
–
–
318 normal, 98 wrinkled
400 normal
150 normal, 138 wrinkled
300 wrinkled
Codominant Type Problem
• A male parent with curly hair
mates with a female parent
with straight hair. Now, their
daughter wants to know
what the chances are that
her kids will be afflicted with
straight hair? She is married
to a male with straight hair.
Dominant/Recessive Problem
• A man has six fingers on
each hand and six toes on
each foot. His wife and their
daughter have normal
number of digits. Extra digits
is a dominant trait. What
fraction of this couple's
children would be expected
to have extra digits?
Multiple Allele Problem
• A case was presented before a judge
in Pennsylvania, in which a woman
(Ricki) of blood type B (Ricki’s mom
was type A & dad was type B),
presented a baby (Bryan) of blood
type O, claiming that Maury was the
father. Maury has type A blood
(Mom- type AB & Dad – type B).
You are the judge. What is your
decision and why?
Dominant/Recessive
• Oak Trees can have either a normal
looking leaf or a very wide looking
leaf. The wide leaf is actually the
dominant trait. If a heterozygous
Oak tree is crossed with a
homozygous normal leaf tree, what
is the chance that the tree will have
wide leaves?
Multiple Allele Problem
• Victor, type AB blood, and Kate,
type A blood, dated for 5 years then
broke up. A year after they broke
up, Victor found out that Kate had a
child, Barney, type O blood. Victor
takes Kate to court for custody of
Barney. Kate claims Barney isn’t
Victors. Is Barney Victor’s son?
Explain
• Darwin’s point is a recessive human
trait where there is a point in the upper
part of the ear. If a heterozygous
person mates with a person with
Darwin’s point, what is the chance that
their kid will NOT have the point?
• Fruit flies are born with wings.
However, they may be born with really
long wings or short wings. Actually, the
short wings are the dominant trait. If a
homozygous long winged fly is crossed
with the heterozygous genotype, what is
the chance that you end up with long
winged flies?
• Humans hairline is a fluctuating experience.
Some people have normal hairlines and some
have severely receding hairlines. However,
normal blends with severely receding to show
somewhat receding. If the male child of two
people with severely receding hairlines, mates
with a woman with no receding hairline, what is
the chance that their kids having any sort of
receding hairline?
• Prince George has the genotype XNY and
does not have hemophilia. His wife,
Princess Margarite is also normal. The
Prince and Princess have had a son die at
the age of 3 of hemophilia.
– What is Princess Margarite's genotype?
– What are the chances that their future children
will have hemophilia? Prove with a square!
• In corn plants a dominant allele is
inherited for yellow kernel color.
However, in the same field we see
yellow kernel corn, brown kernel
corn and white kernel corn. How
could this be explained?
• A man has six fingers on each
hand and six toes on each
foot. His wife and their
daughter have normal
number of digits. Extra digits is
a dominant trait. What
fraction of this couple's
children would be expected
to have extra digits?
• Phenylketonuria (PKU) is an
inherited disease caused by a
recessive allele. If a woman and
her husband are both carriers, what
are the chances that at least one of
their children will have PKU?
1. Guinea Pigs come in two main colors, Black & Yellow.
However, every once in awhile we see a speckled color
Guinea Pig. We find out that Black & Yellow are
codominant. If a black guinea pig and a speckled
guinea pig are mated, what is the chance that you will
end up with a yellow guinea pig?
2. Phenylketonuria (PKU) is an inherited
disease caused by a recessive allele. If
a woman and her husband are both
carriers, what are the chances that at
least one of their children will have
PKU?