Genetics

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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 (e.g., BB, Bb, bb).

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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 (e.g., red hair, tall plant).

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What does heterozygous mean?

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

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What does homozygous mean?

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Homozygous refers to having two identical alleles for a specific gene (e.g., BB or bb).

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What is the dominant allele?

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The dominant allele is the version of a gene that is expressed in the phenotype when at least one copy is present (e.g., G in GG or Gg).

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What is the recessive allele?

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The recessive allele is the version of a gene that is only expressed in the phenotype when two copies are present (e.g., gg).

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What is a Punnett square?

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A Punnett square is a diagram used to predict the genetic outcomes of a cross between two organisms.

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What is the expected phenotype ratio from a cross of two heterozygous parents (e.g., Aa x Aa)?

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The expected phenotype ratio is 3:1 (3 dominant: 1 recessive).

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What is the expected genotype ratio from a cross of two heterozygous parents (e.g., Aa x Aa)?

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The expected genotype ratio is 1:2:1 (1 homozygous dominant: 2 heterozygous: 1 homozygous recessive).

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What is a pedigree chart?

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A pedigree chart is a diagram that shows the occurrence and appearance of phenotypes of a particular gene or organism and its ancestors.