The best answer is amino acids.
Amino acids are the building block of protein. There are 20 different kinds of amino acid but all of them have five common parts.
1. A central carbon
2. A hydrogen atom
3. An amino group
4. an R- group or side chain
5. a carboxyl group.
Amino acids are categorized into two groups:
(a) essential amino acids - they are necessary for growth and tissue maintenance but have to be obtained from diet because the body cannot make them.
(b) non essential amino acids - they can be made or synthesized by the body.
