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How Many Different Kinds of Amino Acids Make Up a Protein?

By M. Gideon Hoyle ; Updated July 18, 2017

Amino acids are substances you rely on to form all the proteins in your body. In turn, you rely on these proteins for vital functions that include gene regulation, formation of cellular structures and transportation of oxygen in your bloodstream. Any given protein contains roughly 20 different amino acids.

Amino Acid Basics

While there are more types of amino acids in your body, you need just 20 to form all of your various proteins. In alphabetical order, they are alanine, arginine, asparagine, aspartic acid, cysteine, glutamic acid, glutamine, glycine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, proline, serine, threonine, tryptophan, tyrosine and valine. Each of these acids has the same basic chemical structure, which includes a central carbon atom, a hydrogen atom, a group of atoms called an amino group and a group of atoms called a carboxyl group. The distinguishing characteristic of each amino acid is a portion of its structure called a side chain or R-group, which has a unique chemical arrangement.

Protein Formation

The specific amino acid content of any given protein is determined by the genetic instructions inside the cell that creates it. The genetic instructions from the parent cell also determine the order of the amino acids inside a protein. While all proteins contain roughly the same complement of amino acids, the order of those acids dictates both the basic shape of each protein and its function in your body. Based on their function, classes of proteins include globular proteins, which trigger chemical reactions; membrane proteins, which receive chemical messages; and fibrous proteins, which provide cellular structure.

Proteins and Peptides

The connections that hold the amino acids together inside any given protein are called peptide bonds. These bonds form between the carboxyl group of one amino acid and the amino group of its neighboring acid. The same type of amino acid can appear inside a protein multiple times. When an amino acid chain contains a relatively short sequence of acids, it is commonly called a peptide rather than a protein. Proteins, in turn, contain relatively long amino acid chains, and scientists sometimes call them polypeptides.


Your body contains roughly 100,000 different proteins. When you eat any food in your diet that contains protein, your body absorbs that protein, breaks it down into individual amino acids, then uses these acids to form the specific proteins you need to support your normal body function. The amino acids arginine, histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan and valine are commonly referred to as essential amino acids. They get this name because your body can’t make them on its own and must get them from dietary sources.

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