Molecular Evolution

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Hox gene Noun

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[hoks jeen]

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Hox gene

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A type of regulatory gene that determines which parts of an embryo develop into specific body structures like limbs.

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Example: This diagram shows that the order of Hox genes on the chromosome matches the head-to-tail order of the body parts they control in a fly.

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Gene Duplication Noun

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[jeen doo-pli-kay-shun]

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Gene Duplication

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A process that produces an extra copy of a gene, which can then mutate and potentially acquire a new function.

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Example: This image shows how a section of a chromosome, which contains genes, is copied, resulting in a duplicated segment.

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Molecular Clock Noun

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[muh-lek-yuh-ler klok]

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Molecular Clock

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A method using mutation rates in DNA to estimate the time that two species have been evolving independently from a common ancestor.

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Example: This diagram shows that as more time passes, more differences (mutations) appear in the DNA of related species, acting like a 'clock' to measure evolutionary time.

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Gene Families Noun

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[jeen fam-uh-leez]

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Gene Families

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A group of related genes that have descended from a single ancestral gene through duplication and modification over evolutionary time.

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Example: This diagram shows how a single ancestral gene evolved differently in various species (like humans and tuna), creating a 'family' of similar but distinct genes.

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Neutral Mutation Noun

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[noo-trul myoo-tay-shun]

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Neutral Mutation

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A genetic mutation that has no discernible effect on an organism's phenotype and tends to accumulate at a constant rate.

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Example: A point mutation changes one DNA base (T to C) in a sequence. This change is 'neutral' if it has no effect on the organism, which the image does not show.

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Genetic Rearrangement Noun

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[juh-net-ik ree-uh-reynj-muhnt]

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Genetic Rearrangement

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A process where parts of genes, such as exons, are mixed and combined, potentially producing new genes with different functions.

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Example: This diagram shows bacterial conjugation, where one bacterium transfers genetic material (a plasmid) to another, resulting in a genetic rearrangement in the recipient cell.