Transcript woman and flowers

Gentoypes and Phenotypes
Monohybrid Crosses
Dihybrid Crosses
In certain breeds of dogs, deafness is
due to a recessive allele (d), and normal
hearing is due to its dominant allele (D).
What percentage of the offspring of a
normal heterozygous (Dd) dog and a
deaf dog (dd) would be expected to
have normal hearing?
DD = normal
Dd = normal
dd = deaf
D
d
d
Dd
dd
d
Dd
dd
2/4 = 50%
d
d
D
Dd
Dd
D
Dd
Dd
DD = normal
Dd = normal
dd = deaf
100%
In humans, normal pigmentation is due to a
dominant allele (C), and albinism is due to
it’s recessive allele (c).
A normal man marries an albino woman.
Their first child is albino. What are
the genotypes of these three people?
Dad had to carry the recessive allele to be able to pass it on to the
child.
If Dad had the genotype (CC), then every offspring would be (Cc),
which would be normal pigmentation.
In minks, brown is dominant over silverblue color.
What are the possible genotypes for the
offspring if you cross a homozygous brown
mink with a silver-blue mink?
b
b
B
Bb
Bb
B
Bb
Bb
In snapdragons, red is not completely
dominant over white flowers. What color
flowers would you expect when you cross a
red flower with a white flower?
What would be the genotypic and
phenotypic ratios of the offspring be?
This is an example of Incomplete Dominance
What type of inheritance pattern is
shown?
In cattle, a cross between a white (rr)
and a red (RR) cow produces a roan
colored cow.
Cross a red-haired and roan colored
cow.
What are the genotypes of the parents?
What are the phenotypic ratios of the
offspring?
• RR x Rr = parent genotypes
RR to Rr = 2:2
R
R
R
RR
RR
r
Rr
Rr
50% Red
50% Roan
In humans, acondroplasia “dwarfism” (D) is dominant
over normal (d).
A homozygous dominant (DD) person dies before the
age of one.
A heterozygous (Dd) person is dwarfed.
A homozygous recessive individual is normal.
A heterozygous dwarf man marries a dwarf
heterozygous woman.
Give the genotypic ratio and the
phenotypes of the possible offspring.
1:2:1 genotypic ratio
D
D
d
DD
Dd
d
Dd
dd
50% chance of having a
dwarf child
25% chance of having a
child with normal
height
25% chance of a DD,
homozygous dwarf
which dies before the
age of one
Sponge Bob Dihybrid Genetics
(S = squarepants, s = roundpants; Y = yellow body, y = blue body)
• If Sponge Bob is heterozygous squarepants,
homozygous yellow body:
• What is his genotype?
• SsYY
• Using the FOIL method, what would the 4 possible
gamete combinations be?
• SY
• SY
• sY
• sY
Sponge Susie Dihybrid Genetics
• If Sponge Susie is roundpants, heterozygous
yellow body:
• What is her genotype?
• ssYy
• Use the FOIL method to find the 4 possible
gamete combinations
• sY
• sy
• sY
• sy
Patrick Dihybrid Genetics
(T = tall head, t = short head; P = pink body, p= orange body)
• If Patrick is heterozygous tall head, heterozygous
pink body:
• What is his genotype?
• TtPp
• Use the FOIL method to find his 4 possible gamete
combinations
• TP
• Tp
• tP
• tp