Scientists Say: Loci

This word describes the location of a gene in your DNA

Long strands of DNA can contain many genes. We call a gene’s spot on a DNA molecule its locus.

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Locus or loci (noun, “LO-kuss” and “LO-sigh”)

Chromosomes are pieces of coiled DNA. They contain many individual genes — segments of DNA carrying instructions for making proteins. Together those genes help make a cell run. Locus is the word we use for the precise place where a gene is located on a chromosome. Figuring out the locus of a gene can be very important to understanding what it does.

In a sentence

A new germ-stopping compound binds to germ DNA at specific loci, so the bacteria can’t breed.

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Power Words

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DNA  (short for deoxyribonucleic acid) A long, double-stranded and spiral-shaped molecule inside most living cells that carries genetic instructions. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.

chromosome  A single threadlike piece of coiled DNA found in a cell’s nucleus. A chromosome is generally X-shaped in animals and plants. Some segments of DNA in a chromosome are genes. Other segments of DNA in a chromosome are landing pads for proteins. The function of other segments of DNA in chromosomes is still not fully understood by scientists.

gene   (adj. genetic) A segment of DNA that codes, or holds instructions, for producing a protein. Offspring inherit genes from their parents. Genes influence how an organism looks and behaves.

genetic  Having to do with chromosomes, DNA and the genes contained within DNA. The field of science dealing with these biological instructions is known as genetics. People who work in this field are geneticists.

locus (in biology) The location of a gene on a chromosome. 

Bethany is the staff writer at Science News for Students. She has a Ph.D. in physiology and pharmacology from Wake Forest University School of Medicine.

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