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Warm-Up Predicting Heredity

Lesson Goals

Discover how can be predicted.

Determine theprobability of

combinations using aPunnett square.

Identify the

an organism based on itsgenotype.

of Define probability anduse it to explain theresults of a geneticcross.

Words to Know

Fill in this table as you work through the lesson. You may also use the glossary to help you.

the likelihood that a given event will occur

the possible genotypes that can result from the mating of two individuals

a part of a whole

to guess based on observations, prior knowledge, or reasoning

a diagram used to predict all possible allele combinations from a genetic cross

Lesson Question

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WK2

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Warm-Up Predicting Heredity

Genotype and Phenotype

The genotype is an organism’s combination.

The phenotype is the physical appearance or characteristics seen in an

.

Genotype: YY

(homozygous

)

Phenotype: Yellow

Genotype: Yy

(heterozygous)

Phenotype:

Genotype: yy

(homozygous

)

Phenotype:

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Predicting HeredityInstruction

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Probability

• Probability is the that a

given event will occur.

• Red apple: 18

• Green apple: 28

• Tangerine:

• Pear: 1

8

Probability Using Percentages

Probability can also be expressed using a . 25 + 25 + 25 + 25 = 100

Fraction: 14

Percentage: 25%

25% 25%

25% 25%

Fraction:

Percentage: 50%

25% 25%

25% 25%

25 + 25 =

Fraction: 34

Percentage: 75%

25% 25%

25% 25%

25 + 25 + 25 = 75%

Fraction: 44

Percentage: 100%

25% 25%

25% 25%

25 + 25 + 25 + 25 = 100%

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Predicting HeredityInstruction

6Slide

Genetic Cross

A is the possible

genotypes that can result from the mating of two individuals.

Genotype of for

seed color

YY ×

First-generation offspring

Punnett Squares

A Punnett square is a diagram used

to predict all possible

combinations from a genetic cross.

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Predicting HeredityInstruction

Punnett Squares

A Punnett square shows a genetic .

YY x yy

Probability of Genotypes

• The probability of each genotype

• YY −

• Yy − 50%

• yy −

25 + 50 + 25 = 100%

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Predicting HeredityInstruction

Probability of Phenotype

• The probability of each phenotype

• Yellow −

• Green −

75 + 25 = 100%

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Genotype and Phenotype

• Homozygous dominant genotypes will show the dominant trait.

• YY = seeds

• Heterozygous genotypes will show the

trait.

• Yy = yellow seeds

• Homozygous recessive genotypes will show the trait.

• yy = seeds

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Summary Predicting Heredity

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Answer

Review: Key Concepts

• A Punnett square is a used to

predict all possible allele combinations from a genetic cross.

• Phenotypes of can be

determined from the genotypes in a Punnett square.

• The of genotypes and

phenotypes can be determined using a Punnett square.

Lesson Question How can traits be predicted?

2Slide

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Summary Predicting Heredity

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