Monohybrid Cross

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Heredity Noun

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[huh-red-i-tee]

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Heredity

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The passing of traits from parents to offspring through their genes.

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Example: This diagram shows how traits are passed from parents to children, where two carrier parents can have offspring who are unaffected, carriers, or affected.

Front

Trait Noun

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[trayt]

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Trait

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A specific feature or characteristic of an organism that is inherited from its parents.

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Example: This chart shows how a trait, like eye color, is inherited from parents, displaying the percentage chance for different outcomes in their children.

Front

Gene Noun

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[jeen]

Back

Gene

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A section of DNA that carries the information for a specific trait.

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Example: This image shows that a gene is a specific section of a DNA molecule, which is tightly coiled to form a chromosome inside a cell's nucleus.

Front

Allele Noun

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[uh-leel]

Back

Allele

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One of the different forms or versions of a single gene.

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Example: This image shows alleles, which are different versions of a gene (like 'A' and 'a'), located on homologous chromosomes.

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Dominant Allele Noun

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[dom-uh-nuhnt uh-leel]

Back

Dominant Allele

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An allele that masks the effect of another allele and is expressed in the phenotype.

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Example: This Punnett square shows that when an allele for green pods (G) is present, the pod is green, making 'G' the dominant allele.

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Recessive Allele Noun

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[ri-ses-iv uh-leel]

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Recessive Allele

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An allele that is only expressed in the phenotype when two copies are present.

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Example: This diagram shows a recessive allele (labeled 'b') on a chromosome, contrasting how it pairs in a homozygous genotype ('bb') versus a heterozygous one ('Bb').

Front

Genotype Noun

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[jee-noh-tahyp]

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Genotype

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The specific combination of alleles, or genetic makeup, that an organism possesses for a particular trait.

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Example: This image shows the three types of genotypes for a single gene: homozygous dominant (AA), heterozygous (Aa), and homozygous recessive (aa) on chromosomes.

Front

Phenotype Noun

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[fee-noh-tahyp]

Back

Phenotype

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

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Example: This diagram shows how an organism's genetic makeup (genotype) determines its observable physical trait (phenotype), such as brown or blue eye color.

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Homozygous Adjective

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[hoh-moh-zahy-guhs]

Back

Homozygous

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Having two identical alleles for a particular gene.

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Example: This diagram shows that a homozygous genotype has two identical alleles (like AA or aa) for a gene on a pair of chromosomes.

Front

Heterozygous Adjective

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[het-er-oh-zahy-guhs]

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Heterozygous

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Having two different alleles for a particular gene.

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Example: This diagram shows a heterozygous genotype (Bb), where a pair of homologous chromosomes has two different alleles for the same gene (one yellow, one blue).