Final answer:
There are 20 different amino acids that are the monomers forming all proteins, enabling a vast diversity of protein structures and functions due to their different combinations and sequences.
Step-by-step explanation:
Proteins are complex biological polymers made from amino acid monomers. In total, there are 20 different amino acids that serve as the monomers for all proteins. Each protein in the human body is made from a unique combination and sequence of these 20 amino acids, contributing to the diversity of proteins' structures and functions. The sequence of amino acids determines the protein's three-dimensional shape, which is crucial for its specific biological role, whether that be as an enzyme, a structural component, or another type of functional molecule. Since proteins can range from a few dozen to thousands of amino acids in length, the number of different protein structures that can be formed is vast, far exceeding 100,000 unique types in humans alone.