Punnett Squares and Heredity

Front

Heredity Noun

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[huh-red-i-tee]

Back

Heredity

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

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Example: This pedigree chart shows how a specific trait (red shape) is passed down from parents to offspring through multiple generations, illustrating heredity in a family.

Front

Genetics Noun

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[juh-net-iks]

Back

Genetics

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

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Example: This diagram shows how genetic information is organized, from a whole cell, to the nucleus, to a chromosome, and finally to the DNA that makes up a gene.

Front

Trait Noun

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[trayt]

Back

Trait

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A specific, genetically determined characteristic or quality of an organism, such as eye color or height.

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Example: This image shows how different combinations of alleles (versions of a gene, shown as 'A' and 'a') on chromosomes create different genotypes (homozygous/heterozygous).

Front

Acquired Trait Noun

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[uh-kwahy-erd trayt]

Back

Acquired Trait

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A characteristic that an organism develops after birth through environmental influences, which is not genetically inherited.

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Example: The muscular bodies shown are acquired traits, developed through exercise and lifestyle, not traits that are inherited from parents.

Front

Gene Noun

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[jeen]

Back

Gene

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A distinct sequence of nucleotides in DNA that codes for a functional product, such as a protein or RNA molecule.

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Example: This diagram shows that a gene is a specific segment of a DNA molecule, which is tightly coiled to form a chromosome, found inside the nucleus of a cell.

Front

DNA Noun

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[dee-en-ey]

Back

DNA

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The molecule carrying genetic instructions for the development, functioning, growth, and reproduction of all known organisms.

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Example: This diagram shows the structure of a DNA molecule, a double helix made of a sugar-phosphate backbone and paired nitrogenous bases (A, T, C, G).

Front

Allele Noun

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[uh-leel]

Back

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, which are different forms of a gene (like 'A' and 'a'), located on a pair of chromosomes.

Front

Dominant Allele Noun

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[dom-uh-nuhnt uh-leel]

Back

Dominant Allele

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An allele that produces the same phenotype whether its paired allele is identical or different.

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Example: This Punnett square shows that when an offspring has both a green allele (G) and a yellow allele (g), it has a green pea pod because the green allele is dominant.

Front

Recessive Allele Noun

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[ri-ses-iv uh-leel]

Back

Recessive Allele

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An allele that produces its characteristic phenotype only when its paired allele is identical.

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Example: This Punnett square shows that a recessive allele ('b') is masked by a dominant allele ('B'), and its trait only appears in offspring with two copies ('bb').

Front

Genotype Noun

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[jee-noh-tahyp]

Back

Genotype

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The specific combination of alleles that constitutes the genetic makeup of an organism for a particular trait.

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Example: This diagram shows that a genotype is the specific combination of alleles (like B and b) on an organism's chromosomes for a particular gene.