Scientists Say: Intron | Science News for Students

Scientists Say: Intron

Not all DNA makes proteins
Jul 9, 2018 — 6:30 am EST

Some parts of DNA code for proteins. Other pieces — called introns — get left out on purpose.


Intron (noun, “IN-tron”)

This is a section of DNA that is removed during the process of making a protein. DNA contains all of the instructions for life in its code, in stretches called genes. DNA is transcribed into RNA, which is a copy of those instructions. Then the RNA is translated into a protein. But the DNA for a protein isn’t one continuous segment. Often, the parts of the DNA that have protein instructions are peppered with introns. The introns get copied into the RNA but are sliced out before the RNA is translated into a protein.

Though introns may not contain instructions for proteins, they’re not junk. Introns help control how genes are translated into proteins. They can help a single gene code for many different proteins, for example, by determining how the RNA formed from the DNA is spliced together. Introns can also protect important parts of DNA from damage — such as when a strand of DNA breaks.

In a sentence

The wings of peppered moths changed color because an intron jumped from one set of DNA to another — carrying a dark wing color with it.

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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. It is built on a backbone of phosphorus, oxygen, and carbon atoms. In all living things, from plants and animals to microbes, these instructions tell cells which molecules to make.

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

intron     A section of DNA or RNA that does not carry the blueprints for making some protein. 

protein     A compound made from one or more long chains of amino acids. Proteins are an essential part of all living organisms. They form the basis of living cells, muscle and tissues; they also do the work inside of cells. Among the better-known, stand-alone proteins are the hemoglobin (in blood) and the antibodies (also in blood) that attempt to fight infections. Medicines frequently work by latching onto proteins.

RNA     A molecule that helps “read” the genetic information contained in DNA. A cell’s molecular machinery reads DNA to create RNA, and then reads RNA to create proteins.