It is not easily recognizable
The answer to the blank i think is bond im not 100% sure though..
Answer: April Cashin-Garbutt, MA, reviewed it (Cantab) Collagen is a protein composed up of amino acids, which are carbon, oxygen, and hydrogen molecules. Glycine, Proline, Hydroxyproline, and Arginine are among the amino acids found in collagen. Collagen makes up around a third of the proteins in the human body.
Explanation:
knowledge!