Genetics and Heredity

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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 observable, heritable traits from parents to offspring from one generation to the next.

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Example: This pedigree chart shows how a genetic trait (indicated by the red shapes) is passed down through three generations of a family.

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Trait Noun

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[trayt]

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Trait

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A specific characteristic of an individual organism, which can be either inherited from parents or acquired during life.

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Example: This diagram shows how a single trait, like the beak shape of finches, can have many variations that are adapted for different functions, like eating seeds or insects.

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DNA Noun

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[dee-en-ey]

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DNA

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Deoxyribonucleic acid, the genetic material containing instructions for an organism to grow, maintain itself, and reproduce.

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Example: This diagram shows that DNA is a double helix structure made of a sugar-phosphate backbone and specific base pairs: Adenine (A) with Thymine (T), and Guanine (G) with Cytosine (C).

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Genetics Noun

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[juh-net-iks]

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Genetics

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The scientific study of heredity, genes, and the variation of inherited characteristics in living organisms.

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Example: This diagram shows how genetic information is organized, starting from a cell, zooming into a chromosome in the nucleus, and then to a gene made of DNA.

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Gene Noun

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[jeen]

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Gene

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A specific segment of DNA that codes for a protein or RNA molecule, controlling an expressed characteristic.

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Example: This diagram shows that a gene is a specific section of a long DNA molecule, which is tightly coiled to form a chromosome inside a cell.

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Allele Noun

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[uh-leel]

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Allele

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One of the different forms or variants of a particular gene that can exist at a specific locus.

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Example: This diagram shows that alleles are different versions of a gene (like 'A' and 'a') located at the same spot on a pair of chromosomes.

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Dominant Allele Noun

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[dom-uh-nuhnt uh-leel]

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Dominant Allele

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An allele that is expressed as a physical trait even when only one copy is present in the genotype.

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Example: This diagram shows two chromosomes, each with an allele for the same gene. The 'dominant' allele represents the version of a gene that is expressed.

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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 as a physical trait when two copies are present in the genotype.

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

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Genotype Noun

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[jee-noh-tahyp]

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Genotype

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

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Example: This diagram shows that a genotype is the specific combination of alleles (like 'A' and 'a') on a pair of chromosomes, resulting in types like AA, Aa, or aa.

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Phenotype Noun

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[fee-noh-tahyp]

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Phenotype

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The observable physical appearance or expressed characteristics of an organism, resulting from its genotype and environment.

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Example: This image shows how different combinations of genes (genotype) on chromosomes result in an observable physical trait, like brown or blue eye color (phenotype).