There are 20 common amino acids that are used in our genetic code.
While there are approximately 500 amino acids that exist, only a specific set of 20 are incorporated into proteins in living organisms, including humans. These are known as the standard amino acids or proteinogenic amino acids.
The 20 Standard Amino Acids
These 20 amino acids are crucial for building proteins, which perform a wide variety of functions in the body, from catalyzing biochemical reactions to providing structural support to cells. The 20 amino acids are:
| Name | Three-Letter Abbreviation | One-Letter Abbreviation |
|---|---|---|
| Alanine | Ala | A |
| Arginine | Arg | R |
| Asparagine | Asn | N |
| Aspartic Acid | Asp | D |
| Cysteine | Cys | C |
| Glutamic Acid | Glu | E |
| Glutamine | Gln | Q |
| Glycine | Gly | G |
| Histidine | His | H |
| Isoleucine | Ile | I |
| Leucine | Leu | L |
| Lysine | Lys | K |
| Methionine | Met | M |
| Phenylalanine | Phe | F |
| Proline | Pro | P |
| Serine | Ser | S |
| Threonine | Thr | T |
| Tryptophan | Trp | W |
| Tyrosine | Tyr | Y |
| Valine | Val | V |
Key Insights:
- Protein Synthesis: These 20 amino acids are the building blocks that are linked together in different sequences to form all the various proteins required by our body.
- Essential vs. Non-Essential: Some of these amino acids are considered essential, which means they cannot be produced by the body and must be obtained through diet. Others are non-essential, as our bodies can synthesize them.
- Beyond the 20: While only 20 standard amino acids are directly coded by DNA, there are also modified amino acids that may occur post-translationally. This means that after the protein is synthesized, it may be modified by adding different functional groups, which can change the amino acid into a different version.
Practical Example:
- Proteins, made up of various combinations of the 20 amino acids, are important for a range of bodily functions, like enzymes that digest food or antibodies that fight infections.
In conclusion, although many amino acids exist, there are 20 standard amino acids used in the genetic code and in the synthesis of proteins.
