Genetics and punnett squares

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What is genetics?

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The study of how different traits are passed from parents to offspring.

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What is a Punnett square?

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A diagram used to predict the outcome of a genetic cross by showing the possible allele combinations from the parents.

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What does homozygous mean?

Back

Having two identical alleles for a particular gene (e.g., AA or aa).

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What does heterozygous mean?

Back

Having two different alleles for a particular gene (e.g., Aa).

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What is a dominant allele?

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An allele that expresses its trait even when only one copy is present (e.g., Y in Yy).

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What is a recessive allele?

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An allele that only expresses its trait when two copies are present (e.g., aa).

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What is the phenotype?

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The observable physical or biochemical characteristics of an organism, determined by its genotype.

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What is the genotype?

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

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What is the probability of obtaining a brown-haired offspring (A-Brown hair; a-blond hair) from Aa x Aa?

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75% Brown Hair and 25% Blond Hair.

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What is the probability of obtaining a homozygous recessive offspring (aa) from Aa x Aa?

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25%.