Single-Factor Punnett Square Notes. Punnett Square A diagram that can be used to predict the gene combinations that might result from a cross.
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Single-Factor Punnett Square Notes
Punnett Square
A diagram that can be used to predict the gene combinations that might result from a cross
Basic Problems:
T = Tall t = short
Tt x TT
T
t
T T
TT TT
Tt Tt
T t
T T
TT TT
Tt Tt
TT: Tt : tt
Genotypic Ratio:_____________
Phenotypic Ratio:_____________
2 : 2 : 0
4 : 0
Basic Problems:
T = Tall t = short
Tt x Tt
T
t
T t
TT Tt
Tt tt
T t
T t
TT Tt
Tt tt
TT: Tt : tt
Genotypic Ratio:_____________
Phenotypic Ratio:_____________
1 : 2 : 1
3 : 1
Word Problems
A = Axial flowers a = terminal flowers
Cross homozygous axial plant with a terminal plant.
__________ X _________ AA aa
Basic Problems:
A = axial a = terminal
AA x aa
A
A
a a
Aa Aa
Aa Aa
A A
a a
Aa Aa
Aa Aa
AA: Aa : aa
Genotypic Ratio:_____________
Phenotypic Ratio:_____________
0 : 4 : 0
4 : 0
Word Problems
A = Axial flowers a = terminal flowers
Cross 2 plants that are heterozygous for axial flowers.
__________ X _________ Aa Aa
Basic Problems:
A = axial a = terminal
Aa x Aa
A
a
A a
AA Aa
Aa aa
A a
A a
AA Aa
Aa aa
AA: Aa : aa
Genotypic Ratio:_____________
Phenotypic Ratio:_____________
1 : 2 : 1
3 : 1
Backwards Problems
G = Green pods g = yellow pods
¾ of the plants produced by a cross between 2 unknown pea plants have green pods and ¼ have yellow pods. What are the genotypes of the parent plants?
__________ X _________
G G
G gg
G
g
G g
G G
G gg
G g
g
Parents Genotypes are….
Gg X Gg
Backwards Problems
G = Green pods g = yellow pods
What cross would result in ½ of the offspring having green pods and ½ of the offspring having yellow pods?
__________ X _________
G G
gg gg
G
g
g g
G G
gg gg
g g
Parents Genotypes are….
Gg X gg
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