Question

Question #05c87

Answer 1

Amino Acids

Explanation:

Proteins (also called polypeptides - "poly" already indicating that we are dealing with a molecule composed of many smaller subunits) are long chains of linked up amino acids.
In humans, there are 20-21 essential amino acids (depending on whether one counts a relatively newly discovered selenium-based amino acid), and the order in which they are linked up dictate the structure and function of the protein.

Hope I could help :)