An amino acid's structure is based around a central carbon atom with four different attachments.
The Basic Structure of an Amino Acid
The central carbon of an amino acid is called the alpha (α) carbon. Attached to this alpha carbon are four crucial components:
- Hydrogen Atom (H): A single hydrogen atom.
- Carboxyl Group (-COOH): An acidic functional group that can donate a hydrogen ion.
- Amino Group (-NH2): A basic functional group that can accept a hydrogen ion.
- R Group (Side Chain): This is an organic side chain that is unique to each of the 20 different amino acids, and determines the specific properties of the amino acid.
| Component | Chemical Formula | Description |
|---|---|---|
| Alpha Carbon | C | Central carbon atom. |
| Hydrogen Atom | H | Single hydrogen atom. |
| Carboxyl Group | -COOH | Acidic functional group. |
| Amino Group | -NH2 | Basic functional group. |
| R Group | Varies | Unique side chain, different for each amino acid. |
Importance of the R Group
The R group is the key to the diversity and function of amino acids. Each of the 20 common amino acids has a unique R group, which can be:
- Nonpolar and hydrophobic
- Polar and hydrophilic
- Acidic (negatively charged)
- Basic (positively charged)
These variations in R groups lead to different interactions and structures for protein, based on the combination of all the constituent amino acids.
The reference provided states that: "An amino acid's structure consists of a central carbon atom attached to a hydrogen, an acidic carboxyl group (−COOH), an amino group (−NH2) and an organic side chain (also called an R group). The side chain is unique in each of the 20 amino acids."
