Transcript Single-gene (monohybrid) cross

Cross homozygous dominant tall plant and a
heterozygous tall plant.
a.
What are the Parent genotypes?
b.
What are the F1 phenotype frequencies?
c.
What are the F1 genotype frequencies?
Cross homozygous dominant tall plant and a
heterozygous tall plant.
a.
What are the Parent genotypes?
b.
What are the F1 phenotype frequencies?
c.
What are the F1 genotype frequencies?
T
T = tall
T = short
T
T
TT
TT
tall
t
Tt
tall
tall
Tt
tall
a. TT and Tt
b. All Tall
c. 2 TT : 2 Tt
What gametes can be formed from the
following organism?
TtHh
T=
t =
H=
h=
straight-tailed
curly-tailed
short-haired
long-haired
What gametes can be formed from the
following Straight-tailed, short-haired dog?
TtHh
Use the foil method:
TH
Th
tH
th
What are the genotype and
phenotype ratios from crossing
TtHh with TTHH?
TtHh x TTHH
TH
TH
TH
Th
tH
th
T = straight tailed
t = curly tailed
H = short haired
h = long haired
F1 Phenotype ratio:
TH
F1 Genotype ratio:
TH
TH
TH
TH
Th
tH
th
TTHH
TTHh
TtHH
TtHh
Straight, short Straight, short Straight, short Straight, short
T = straight tailed
t = curly tailed
TTHH
H = short haired
h = long haired
TTHh
TtHH
TtHh
Straight, short Straight, short Straight, short Straight, short
TH
TTHH
TTHh
TtHH
TtHh
Straight, short Straight, short Straight, short Straight, short
TH
TTHH
TTHh
TtHH
TtHh
Straight, short Straight, short Straight, short Straight, short
F1 Phenotype ratio:
All straight-tailed
All short-haired
F1 Genotype ratio:
4 TTHH
4 TTHh
4 TtHH
4 TtHh
If cross-pollinating a red snapdragon and
white snapdragon produce all pink
snapdragons:
a.
What is the percent chance a
white flower will result from the
self pollination of one of the pink
offspring?
b.
What kind of inheritance is this?
W
R = red
W = white
R
R
RW
RW
pink
W
RW
pink
pink
RW
pink
R
R = red
W = white
R
W
RR
RW
red
W
pink
RW
WW
pink
white
a. 25% chance two pink-flowered plants produce a whiteflowered plant
b. Type of inheritance: incomplete dominance
Can a type A mother and type B father
have a child with type O blood?
IA = A allele
IB = B allele
i = O allele
Genotype possibilities for Type A mom:
IAIA or
IAi
Genotype possibilities for Type B dad:
IBIB
or
IBi
Can a type A mother and type B father
have a child with type O blood?
IA = A allele
IB = B allele
i = O allele
Genotype possibilities for Type A mom:
IAIA
or
IAi
Ib
Genotype possibilities for Type B dad:
IBIB
or
IBi
i
Ia
i
IaIb
Ibi
Type AB
Type B
Iai
ii
Type A
Type O
What percent chance does a child have
of being colorblind if the mother is normal
but a carrier, and the father is normal?
What if the father was colorblind?
What is mom’s genotype?
What is dad’s genotype?
What percent chance does a child have of
being colorblind if the mother is normal but a
carrier, and the father is normal? What if the
father was colorblind?
Problem 1: Carrier mother, Normal father
What is mom’s genotype? XBXb
What is dad’s genotype? XBY
What percent chance does a child have of
being colorblind if the mother is normal but a
carrier, and the father is normal? What if the
father was colorblind?
Problem 1: Carrier mother, Normal father
What is mom’s genotype?
XBXb
XB
What is dad’s genotype?
XBY
B B
XB X X
•
•
Daughters: 0%
Sons: 50%
Xb
Y
XBY
Normal female
Normal male
XBXb
XbY
Carrier female
Colorblind male
What percent chance does a child have of
being colorblind if the mother is normal but a
carrier, and the father is normal? What if the
father was colorblind?
Problem 2: Carrier mother, Colorblind father
What is mom’s genotype? XBXb
What is dad’s genotype? XbY
What percent chance does a child have of
being colorblind if the mother is normal but a
carrier, and the father is normal? What if the
father was a carrier?
Problem 2: Carrier mother, Colorblind father
What is mom’s genotype?
b
X
XBXb
What is dad’s genotype?
BXb
B
X
X
XbY
Carrier female
•
•
Daughters: 50%
Sons: 50%
Xb
XbXb
Colorblind female
Y
XBY
Normal male
XbY
Colorblind male
Feather length in ducks can be short or long. Choose a letter to use for the feather
length gene. Determine which allele (short or long) is dominant and which is
recessive. Supply the genotypes and phenotypes of the individuals in the pedigree.
You will have five individuals where you only know one allele.
Feather length in ducks can be short or long. Choose a letter to use for the feather
length gene. Determine which allele (short or long) is dominant and which is
recessive. Supply the genotypes and phenotypes of the individuals in the pedigree.
You will have five individuals where you only know one allele.
ff
ff
ff
F = short
f = long
ff
ff
Feather length in ducks can be short or long. Choose a letter to use for the feather
length gene. Determine which allele (short or long) is dominant and which is
recessive. Supply the genotypes and phenotypes of the individuals in the pedigree.
You will have five individuals where you only know one allele.
F_
F_
ff
ff
F_
F_
F_
F_
F_
ff
F_
F_
ff
F = short
f = long
F_
ff
F_
F_
F_
F_
F_
Feather length in ducks can be short or long. Choose a letter to use for the feather
length gene. Determine which allele (short or long) is dominant and which is
recessive. Supply the genotypes and phenotypes of the individuals in the pedigree.
You will have five individuals where you only know one allele.
Ff
Ff
ff
ff
Ff
Ff
F_
Ff
F_
ff
Ff
F_
ff
F = short
f = long
F_
ff
Ff
Ff
Ff
Ff
F_
An unaffected man marries a woman who is a carrier
for Duchenne Muscular Dystrophy, which is attributed
to an X-linked gene. They have four children, one with
Duchenne, one carrier daughter and a daughter and
son who are unaffected. The child with Duchenne
Muscular Dystrophy dies in childhood. The carrier
daughter marries and has three children of her own,
two of which are carriers and one of which is
unaffected.
a. Draw a pedigree for this family.
b. What is the most likely sex of these two carrier
children given the fact that they are unaffected by
the X-linked gene?
An unaffected man marries a woman who is a carrier for Duchenne
Muscular Dystrophy, which is attributed to an X-linked gene. They have
four children, one with Duchenne, one carrier daughter and a daughter
and son who are unaffected. The child with Duchenne Muscular
Dystrophy dies in childhood. The carrier daughter marries and has three
children of her own, two of which are carriers and one of which is
unaffected.
a.
b.
Draw a pedigree for this family.
What is the most likely sex of these two carrier children given the fact
that they are unaffected by the X-linked gene?
-For a sex-linked recessive disorder, only females can be carriers.
XDY XDXd
XdY or XDXD
XDXd
XDXd XDY
XDXD
XDXd
XDXD
XDY
Male
Normal
44
none
2
Male
Abnormal
44
XXY
3
Female
Normal
45
Trisomy 21
2
Male
Abnormal
45
Trisomy 18
2
Male
Abormal
45
Trisomy 13
2