Genetics

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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 genes, heredity, and the variation of inherited characteristics in organisms from one generation to another.

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Example: This diagram shows how genetic material is organized, from a large cell down to the nucleus, chromosomes, genes, and the DNA that makes them up.

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Heredity Noun

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[huh-red-i-tee]

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Heredity

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The biological process of passing genetic traits and characteristics from parents to their offspring through genes.

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Example: This pedigree chart shows how a specific trait (red shapes) is passed down from parents to their children and grandchildren through multiple generations.

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DNA Noun

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[dee-en-ey]

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DNA

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Deoxyribonucleic acid, a self-replicating molecule that carries the genetic instructions for the development and function of all known organisms.

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

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Chromosome Noun

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[kroh-muh-sohm]

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Chromosome

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A thread-like structure of nucleic acids and protein found in the nucleus, carrying genetic information in the form of genes.

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Example: This diagram shows that a chromosome is a structure found inside a cell's nucleus and is made of tightly coiled DNA.

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Gene Noun

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[jeen]

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Gene

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A specific sequence of nucleotides in DNA that is the basic physical and functional unit of heredity.

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Example: This diagram 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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One of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

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Example: This diagram shows alleles as different versions of a gene (represented by 'A' and 'a') on a pair of chromosomes, illustrating homozygous (AA, aa) and heterozygous (Aa) combinations.

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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 produces the same phenotype whether its paired allele is identical or different, masking the effect of a recessive allele.

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Example: This diagram shows that a dominant allele (capital 'A') is a version of a gene that is expressed in both the homozygous (AA) and heterozygous (Aa) genotypes.

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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 produces its characteristic phenotype only when its paired allele is identical, being masked by a dominant allele.

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Example: This image shows a recessive allele (labeled 'b') on a chromosome. For a recessive trait to appear, an individual must be homozygous (bb).

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Genotype Noun

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[jee-noh-tiep]

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Genotype

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The specific genetic makeup or set of alleles of an organism for a particular trait or set of traits.

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Example: This image shows examples of genotypes by illustrating the difference between homozygous (two identical alleles, like BB or bb) and heterozygous (two different alleles, like Bb) pairs on chromosomes.

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Phenotype Noun

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[fee-noh-tiep]

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Phenotype

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The set of observable physical or biochemical characteristics of an individual resulting from the interaction of its genotype with the environment.

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Example: This image shows that an organism's genetic makeup (genotype, like AA, Aa, or aa) determines its observable physical traits (phenotype, like brown or blue eyes).