Transcript 11-2 Probability and Punnett Squares

11-2 Probability and Punnett
Squares
11-2 Probability and Punnett Squares
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11-2 Probability and Punnett Squares
Genetics and Probability
Genetics and Probability
The likelihood that a particular event will occur is
called probability.
Let’s consider a coin toss.
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11-2 Probability and Punnett Squares
PROBABILITY CAN BE USED
TO PREDICT THE OUTCOMES
OF GENETIC CROSSES.
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11-2 Probability and Punnett Squares
Punnett Squares
Punnett Squares
Offspring can be determined by a Punnett
square.
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11-2 Probability and Punnett Squares
Punnett Squares
A capital letter
represents the
dominant allele for tall.
A lowercase letter
represents the
recessive allele for
short.
In this example,
T = tall
t = short
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11-2 Probability and Punnett Squares
Punnett Squares
Gametes produced by
each F1 parent are
shown along the top
and left side.
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11-2 Probability and Punnett Squares
Punnett Squares
Organisms that have two identical alleles for a
particular trait are said to be homozygous (TT or tt).
Organisms that have two different alleles for the
same trait are heterozygous (Tt).
Homozygous organisms are true-breeding for a
particular trait.
Heterozygous organisms are hybrid for a particular
trait.
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11-2 Probability and Punnett Squares
Punnett Squares
All of the tall plants have the same Phenotype, or
Physical characteristics.
The tall plants do not have the same Genotype, or
Genetic makeup.
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11-2 Probability and Punnett Squares
The genotype of one third of the tall plants is TT,
While the genotype of two thirds of the tall plants is Tt.
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11-2 Probability and Punnett Squares
Punnett Squares
These plants have
different genotypes
(TT and Tt), but they
have the same
phenotype (tall).
TT
Homozygous
Tt
Heterozygous
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11-2
Click to Launch:
Continue to:
- or -
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11-2
Two F1 plants that are homozygous for
shortness are crossed. What percentage of the
offspring will be tall?
a. 100%
b. 50%
c. 0%
d. 25%
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11-2
The Punnett square allows you to predict
a. only the phenotypes of the offspring from a
cross.
b. only the genotypes of the offspring from a
cross.
c. both the genotypes and the phenotypes
from a cross.
d. neither the genotypes nor the phenotypes
from a cross.
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END OF SECTION