Embed Size (px)
Citation preview
Pedigree Charts
Quiz 7B
Pedigree Charts
Besides showing possible gene pairings, a pedigree chart gives the probability of each pairing.
It shows how often, on the average, a given pairing will occur.
Pea Plant Characteristics
Show a cross between a tall and short pea plant
Step One
Write down the set of contrasting traits.
Assign the capitol letter to the dominant trait and the lower case letter to the recessive trait.
Tall
Short
T
t
Show a cross between a tall and short pea plant
Step Two
Write down possible genotypes and phenotypes.
TT
Tt
tt
Tall
Tall
Short
Purebred dominant
hybrid
Purebred recessive
Show a cross between a tall and short pea plant
Step Three
Fill in the genotypes of the parents on the pedigree chart.
Pedigree Chart
P1 P2
F1
Parents
P1 P2
In the circle - the possible gametes of the female are listed.
In the square - the possible gametes of the male are listed
TT tt
Show a cross between a tall and short pea plant
Step Four
Fill in the genetic possibilities of the F1
on the pedigree chart.
Cross between a tall and short pea plant
P1 P2
F1
TT tt
Take first gene from the female and first gene from the male and place in the first offspring spot.
Tt
Cross between a tall and short pea plant
P1 P2
F1
TT tt
Take first gene from the female and second gene from the male and place in the second offspring spot.
Tt Tt
Cross between a tall and short pea plant
P1 P2
F1
TT tt
Take second gene from the female and first gene from the male and place in the third offspring spot.
Tt Tt Tt
Cross between a tall and short pea plant
P1 P2
F1
TT tt
Take second gene from the female and second gene from the male and place in the fourth offspring spot.
Tt Tt Tt Tt
Show a cross between a tall and short pea plant
Step Five
Write down the genotypic ratio and the phenotypic ratio.
Purebred dominant : Hybrid : Purebred recessive
Dominant : Recessive
Cross between a tall and short pea plant
P1 P2
F1
TT tt
0:4:0
Tt Tt Tt Tt
Genotypic Ratio
4:0 Phenotypic Ratio
