20 Amino Acids 3

Amino acids are organic compounds containing an amino group (-NH2) and a carboxyl group (-COOH). This is the general structure of an amino acid:

General Amino Acid Structurewhere R is the side chain functional group that distinguishes one amino acid from another.

This is a table of the 20 amino acids derived from proteins. The table contains the amino acid’s name, common abbreviation and symbol, linear structure and skeletal structure.

 Name  Symbol  Linear Structure Skeletal Structure
Alanine ala A CH3-CH(NH2)-COOH Alanine Structure
Arginine arg R HN=C(NH2)-NH-(CH2)3-CH(NH2)-COOH Arginine Structure
Asparagine asn N H2N-CO-CH2-CH(NH2)-COOH Asparagine Structure
Aspartic Acid asp D HOOC-CH2-CH(NH2)-COOH Aspartic Acid Structure
Cysteine cys C HS-CH2-CH(NH2)-COOH Cysteine Structure
Glutamic Acid glu E HOOC-(CH2)2-CH(NH2)-COOH Glutamic Acid Structure
Glutamine gln Q H2N-CO-(CH2)2-CH(NH2)-COOH Glutamine Structure
Glycine gly G NH2-CH2-COOH Glycine Structure
Histidine his H NH-CH=N-CH=C-CH2-CH(NH2)-COOH Histidine Structure
Isoleucine ile I CH3-CH2-CH(CH3)-CH(NH2)-COOH Isoleucine Structure
Leucine leu L (CH3)2-CH-CH2-CH(NH2)-COOH Leucine Structure
Lysine lys K H2N-(CH2)4-CH(NH2)-COOH Lysine Structure
Methionine met M CH3-S-(CH2)2-CH(NH2)-COOH Methionine Structure
Phenylalanine phe F Ph-CH2-CH(NH2)-COOH Phenylanaline Structure
Proline pro P NH-(CH2)3-CH-COOH Proline Structure
Serine ser S HO-CH2-CH(NH2)-COOH Serine Structure
Threonine thr T CH3-CH(OH)-CH(NH2)-COOH Tyrosine Structure
Tryptophan trp W Ph-NH-CH=C-CH2-CH(NH2)-COOH Tryptophan Structure
Tyrosine tyr Y HO-Ph-CH2-CH(NH2)-COOH Tyrosine Structure
Valine val V (CH3)2-CH-CH(NH2)-COOH Valine Structure

Amino acids are often grouped by the chemistry of the side chain. These groups are polar-uncharged, polar-charged and non-polar.

Eight of the 20 amino acids are polar-uncharged: Asparagine, cysteine, glutamine, histidine, serine, threonine, tryptophan and tyrosine.

Eight of the 20 amino acids are non-polar: alanine, glycine, isoleucine, leucine, methionine, phenylalanine, proline, and valine.

The final four are polar-charged: arginine, aspartic acid, glutamic acid, and lysine.

A downloadable study sheet of this information is available here.

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3 thoughts on “20 Amino Acids

  • Jake Klingensmith

    Hey! These are some great diagrams! It’s surprisingly hard to find a consistent diagramming notation for all 20 amino acids. Just a heads up though, on your site, Threonine is linked to the diagram for Tyrosine. I don’t think the diagram for Threonine is actually posted.