Question

What are the functional groups of an amino acid?

Answer 1

Functional groups are the molecules attached on an organic compound. They impart specialized characteristics in chemical reactions and also in physical properties of the compound. Amino acids are the simplest unit of proteins. Amino acids are made of two functional groups. Example of an amino acid is glycine.

Complete answer:
Amino acids act as a monomer for proteins. Proteins are one of the essential nutrients required for the growth of our body. As the name suggests amino acids contain two functional groups. Functional groups are the molecules that give a particular characteristic to any organic compounds. Examples of some common functional groups are alcohol (hydroxyl, OH), ketones (CO), aldehydes (CHO), carboxylic acids (COOH), amines $\left( N{{H}_{2}} \right)$, etc.
Amino acids contain an amine group and a carboxylic acid group which are$\left( N{{H}_{2}} \right)$and $\left( -COOH \right)$respectively. For instance, the simplest amino acid is glycine that is${{H}_{2}}N-\underset{H}{\overset{H}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-COOH$ it is optically inactive, while simplest optically active amino acid is alanine that is${{H}_{2}}N-\underset{C{{H}_{3}}}{\overset{H}{\mathop{\underset{|}{\overset{|}{\mathop{C}}}\,}}}\,-COOH$. They are represented by the first three letters of their name as gly (glycine) and ala (alanine).
Hence, the functional groups in amino acids are amine group $\left( N{{H}_{2}} \right)$ and a carboxylic acid group $\left( -COOH \right)$.

Note:
Amino acids behave like a salt in spite of having amine and a carboxylic acid group. This is due to the fact that they are present as zwitterion means an ion having a positive as well as a negative charge. It is neutral in solutions as the carboxylic acid gives the proton that is accepted by the amine group as, ${{H}_{2}}N-C{{H}_{2}}-COOH\rightleftarrows \overset{+}{\mathop{N{{H}_{3}}}}\,-C{{H}_{2}}-CO{{O}^{-}}$.