Punnett Squares

Front

What is a Punnett Square?

Back

A Punnett Square is a diagram used to predict the outcome of a genetic cross by showing the possible combinations of alleles from the parents.

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What does homozygous mean?

Back

Homozygous refers to having two identical alleles for a particular gene (e.g., AA or aa).

Front

What does heterozygous mean?

Back

Heterozygous refers to having two different alleles for a particular gene (e.g., Aa).

Front

What is a genotype?

Back

A genotype is the genetic makeup of an organism, represented by the alleles it possesses (e.g., AA, Aa, aa).

Front

What is a phenotype?

Back

A phenotype is the observable physical or biochemical characteristics of an organism, determined by its genotype (e.g., tall or short plants).

Front

What is the significance of dominant alleles?

Back

Dominant alleles are expressed in the phenotype even when only one copy is present (e.g., A in Aa).

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What is the significance of recessive alleles?

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Recessive alleles are only expressed in the phenotype when two copies are present (e.g., aa).

Front

How do you determine the possible genotypes from a Punnett Square?

Back

By filling in the squares with the combinations of alleles from each parent, you can determine the possible genotypes of the offspring.

Front

What is the expected genotype ratio from a monohybrid cross of two heterozygous parents (Aa x Aa)?

Back

The expected genotype ratio is 1 AA : 2 Aa : 1 aa.

Front

What is the expected phenotype ratio from a monohybrid cross of two heterozygous parents (Aa x Aa)?

Back

The expected phenotype ratio is 3 dominant : 1 recessive.