1. Carbon (C): Forms the backbone of the amino acid.

2. Hydrogen (H): Found in various positions throughout the molecule.

3. Oxygen (O): Part of the carboxyl group (COOH).

4. Nitrogen (N): Found in the amino group (NH2).

Additionally, some amino acids contain sulfur (S), which is found in the side chain of cysteine and methionine.

These elements are combined in specific arrangements to form the basic structure of an amino acid:

* Amino group (NH2): Attached to the central carbon atom.

* Carboxyl group (COOH): Also attached to the central carbon atom.

* Hydrogen atom (H): Attached to the central carbon atom.

* Side chain (R group): Attached to the central carbon atom and varies between different amino acids.

The R group is the distinguishing feature that determines the unique properties of each amino acid.