Amino acids are the building blocks of proteins, and they are not composed of subunits.

An amino acid is a single molecule containing:

* An amino group (-NH2)

* A carboxyl group (-COOH)

* A side chain (R group) which varies between different amino acids and gives each amino acid its unique properties.

Proteins are made up of chains of amino acids, connected by peptide bonds. These chains can be very long and complex, folding into intricate three-dimensional structures.

Think of it this way:

* Amino acid: Like a single Lego brick

* Protein: Like a complex structure built from many Lego bricks connected together.

So, while proteins are composed of multiple amino acids, amino acids themselves are not made up of subunits.