Title: Punnett Squares
1Punnett Squares
2Punnett Squares
A Model used to show the possible ways genes
can combine during fertilization.
3Punnett Squares
Punnett Squares
Helps you keep track of traits.
4.
Punnett Squares
Dominant and recessive alleles are represented by
letters.
5Punnett Squares
A capital letter (T) is used for dominant alleles.
T
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A lowercase letter (t) is used for recessive
alleles.
t
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If you wanted to know the type of offspring a
cross between two parents would produce, you can
use a punnett square.
Tt x Tt TT,Tt for tall Tt for short
8Punnett Squares
The letters representing the alleles from one
parent are placed along the top of the square.
T t
9Punnett Squares
The letters representing the two alleles from the
second Parent are places along the side of the
square.
T t
10Punnett Squares
T t x T t
T t
T t
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Squares are filled by writing the letter at the
top beside the letter on the side.
T t
T t
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The letters in each of the squares represents the
Genotypes of the offspring that the parents could
produce.
T t
T t
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The genotype (genetic makeup) can be used to
predict the phenotype (physical appearance) of
the offspring.
14Punnett Sqaures
Genotype Phenotype
- TT tall
- Tt tall
- Tt tall
- t t short
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Probability the ratio that a particular event
could occur.
31
3 would be tall 1 would be short
out of 4 offspring
16Punnett Squares
- Help you keep track of traits.
- Predict genotype and phenotype.
- Calculate probability.