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Amino acids

Amino acids are the basic units of proteins. They are important organic molecules that consist of:

  • An amino group, $$\ce{-NH2}$$
  • A carboxyl group, $$\ce{-COOH}$$
  • An R-group (a side chain).

These groups are linked via a central carbon, known as the $$\alpha$$-carbon.

The R-group varies across amino acids.

In glycine, the R group is simply a hydrogen.
In glycine, the R group is simply a hydrogen.

The R-group influences the way an amino acid can interact through intermolecular (between molecules) or intramolecular (within the molecule itself) bonding.

Amino acids can be classified as non-polar, polar, acidic or basic based on the R-group. Glycine is a special case where the R-group is a single hydrogen atom.

There are 22 amino acids found in proteins. Humans use 20 of them.

There are nine amino acids that the human body cannot produce. These must be obtained from the diet, and are called essential amino acids.