1. Amino group (NH2): This is a basic group that can accept a proton, giving the amino acid its characteristic basic properties.
2. Carboxylic acid group (COOH): This is an acidic group that can donate a proton, giving the amino acid its characteristic acidic properties.
3. Hydrogen atom (H): This is a simple hydrogen atom.
4. Side chain (R group): This is the unique group that distinguishes one amino acid from another. Each amino acid has a different R group, which gives it its specific chemical properties.
These four groups are attached to the central carbon atom, also known as the alpha carbon.
