Scientists Say: Strain

In cell biology, this word isn’t about stretching

These mice look incredibly different but are the same species. What are they? Strains!

Enrique Ramos Lopez/istockphoto

Strain (noun, “Strayn”) 

This is a way to characterize organisms that belong to the same species, but that have small, definite differences. For example, scientists have bred different strains of lab mice that may always be large, small or perhaps susceptible to different diseases. Animals belonging to different strains are still able to interbreed. Animals aren’t the only organisms that show “strain” differences. Fungi and microbes can as well.

In a sentence

By tweaking genes, scientists created a strain of yeast that stored more fat and lived longer.

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Power Words

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species   A group of similar organisms capable of producing offspring that can survive and reproduce.

strain    (in biology) Organisms that belong to the same species that share some small but definable characteristics. For example, biologists breed certain strains of mice that may have a particular susceptibility to disease. Certain bacteria or viruses may develop one or more mutations that turn them into a strain that is immune to the ordinarily lethal effect of one or more drugs. (in medicine) Stretching or tearing of muscle or tendons, which are the fibrous bands that connect muscle to bone. (in physics) The forces or stresses that seek to twist or otherwise deform a rigid or semi-rigid object.

taxonomy   The study of organisms and how they relate or have branched off (over evolutionary time) from earlier organisms. Often the classification of where plants, animals or other organisms fit within the Tree of Life will be based on such features as how their structures are formed, where they live (in air or soil or water), where they get their nutrients. Scientists who work in this field are known as taxonomists.

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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