Patterns of Inheritance

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Gene Noun

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[jeen]

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Gene

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A segment of DNA that provides instructions for a specific protein, which in turn influences a particular trait.

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

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Allele Noun

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[uh-leel]

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Allele

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A specific version or variant of a gene that occupies a specific position on a chromosome and controls a trait.

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Example: This diagram shows that an allele is a specific version of a gene (like the pink 'A' or blue 'a') located on a chromosome.

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Genotype Noun

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[jee-noh-tahyp]

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Genotype

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The specific combination of alleles, such as homozygous or heterozygous, that an individual possesses for a particular genetic trait.

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Example: This image shows examples of genotypes, which are the specific letter combinations for a gene, like AA, Aa, or aa, found on chromosomes.

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Phenotype Noun

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[fee-noh-tahyp]

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Phenotype

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The set of observable physical or biochemical characteristics of an individual resulting from their genotype and environmental influences.

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Example: An organism's genetic code (genotype), represented by DNA, determines its observable physical traits (phenotype), represented by the person.

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Homozygous Adjective

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[hoh-moh-zahy-guhs]

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Homozygous

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A genetic condition where an individual has inherited two identical alleles for a particular gene from their parents.

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Example: This diagram shows that homozygous means having two identical alleles for a gene, like the two capital 'B's (BB) or two lowercase 'b's (bb).

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Heterozygous Adjective

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[het-er-oh-zahy-guhs]

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Heterozygous

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A genetic condition where an individual has inherited two different alleles for a particular gene from their parents.

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Example: This shows a heterozygous gene pair, where the two alleles (versions of a gene) are different, represented by a capital 'A' and a lowercase 'a'.

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Gamete Noun

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[gam-eet]

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Gamete

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A mature reproductive cell, such as an egg or sperm, that contains a single set of chromosomes (haploid).

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Example: This image shows the two types of gametes, or reproductive cells: the sperm and the ovum. These are the cells that join during fertilization.

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Autosome Noun

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[aw-tuh-sohm]

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Autosome

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Any chromosome that is not a sex chromosome and appears in pairs in the somatic cells of an organism.

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Example: This image shows the 22 pairs of autosomes, which are the non-sex chromosomes found in humans, arranged in a circle for clear visualization.

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Sex Chromosome Noun

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[seks kroh-muh-sohm]

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Sex Chromosome

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A type of chromosome involved in determining the sex of an organism, typically designated as X or Y.

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Example: This image shows the 'X' shape of a replicated chromosome, a structure that carries genetic information. Sex chromosomes, like this one, determine an organism's biological sex.

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Incomplete Dominance Noun

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[in-kuhm-pleet dom-uh-nuhns]

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Incomplete Dominance

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A form of inheritance where the heterozygous phenotype is an intermediate blend between the two homozygous parental phenotypes.

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Example: Crossing a red flower with a white flower results in all pink offspring, because neither the red nor white allele is completely dominant.