1. Carbon (C)

2. Hydrogen (H)

3. Oxygen (O)

4. Nitrogen (N)

These elements form the basic structure of an amino acid, which consists of:

* A central carbon atom: This carbon atom is bonded to four different groups:

* An amino group (-NH2)

* A carboxyl group (-COOH)

* A hydrogen atom (-H)

* A side chain (R group)

The R group varies between different amino acids, and it is responsible for the unique properties of each amino acid.