Genetics Terminology

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Allele

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A section of DNA that codes for a specific trait, represented by a letter.

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Genotype

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A two-letter code used to identify a person's genetic makeup.

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Phenotype

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Physical characteristics/appearance of an individual.

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Homozygous

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An individual that has two identical alleles represented in a genotype, also known as purebred.

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Heterozygous

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An individual that has two different alleles represented in a genotype, also known as a hybrid.

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Recessive

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A trait that is only expressed when no dominant trait is present. It is represented by a lowercase letter.

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Dominant

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A trait that will always show up if the dominant allele is present, represented by an uppercase letter.

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Punnett Square

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Used to predict the traits that the offspring of two parents will have; it shows what is likely to happen in a genetic cross.