Genotypes and Phenotypes

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What is a genotype?

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A genotype is the genetic makeup of an organism, represented by the alleles it possesses.

Tags

NGSS.HS-LS3-1

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What is a phenotype?

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A phenotype is the observable physical or biochemical characteristics of an organism, determined by its genotype.

Tags

NGSS.HS-LS4-3

NGSS.HS-LS4-4

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What does it mean if an organism is homozygous?

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An organism is homozygous if it has two identical alleles for a particular gene (e.g., AA or aa).

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What does it mean if an organism is heterozygous?

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An organism is heterozygous if it has two different alleles for a particular gene (e.g., Aa).

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What is a dominant allele?

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A dominant allele is an allele that expresses its trait even when only one copy is present in the genotype.

Tags

NGSS.HS-LS3-1

NGSS.HS-LS3-2

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What is a recessive allele?

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A recessive allele is an allele that only expresses its trait when two copies are present in the genotype.

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How are dominant alleles represented?

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Dominant alleles are represented by capital letters (e.g., A).

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How are recessive alleles represented?

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Recessive alleles are represented by lowercase letters (e.g., a).

Front

What is the phenotype of a homozygous dominant genotype (AA)?

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The phenotype of a homozygous dominant genotype is the dominant trait.

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What is the phenotype of a homozygous recessive genotype (aa)?

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The phenotype of a homozygous recessive genotype is the recessive trait.