Scientists Say: Amino Acid

These tiny molecules wear many useful hats


This is the basic structure of an amino acid. On the left is an amine, a nitrogen atom with two hydrogen atoms. On the right is a carboxyl, a carbon atom with two oxygen atoms and a hydrogen. In the center is the “R” group, a part of the molecule that is different for every type of amino acid.

YassineMrabet/Public Domain

Amino Acid (noun, “Ah-MEEN-oh AH-sid”)

This is a type of molecule found in living cells. Amino acids by themselves can serve as chemical messengers. When they link up into chains, amino acids form proteins, the engines that help our cells function.

Each amino acid is made of three parts. One is an amine, which is a nitrogen atom bound to two hydrogens. Another is a carboxyl group. This is a carbon atom with two oxygen atoms and one hydrogen atom. The third group is called the “R” group. The “R” group is a chain of atoms that is specific to each type of amino acid. It can be as simple as a single hydrogen atom, as in the amino acid glycine. Or it can be as complex as a big double ring of carbon atoms, like in the amino acid tryptophan (famously found in turkey).

Animals, including humans, need about 20 amino acids to construct all the proteins we require for survial. But we can only make about half of those in our own cells. Those are called nonessential amino acids, because our bodies can make them on their own. The others are essential amino acids. It’s essential that we get these amino acids from the food we eat.

In a sentence

A single amino acid change could be what makes Zika such a brain cell killer.   

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Bethany Brookshire was a longtime staff writer at Science News Explores and is the author of the book Pests: How Humans Create Animal Villains. She has a Ph.D. in physiology and pharmacology and likes to write about neuroscience, biology, climate and more. She thinks Porgs are an invasive species.

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