Explain the process of formation of complex proteins. 

Amino acid joins together to for long polypeptide chains, these chains join together to form a complex protein structure. These are basically called Quaternary structures of proteins.

In Quaternary structures, proteins are attached with each other via non-covalent interactions and shereochemical arrangements of individual protein molecules.

Examples of Quaternary proteins are collagen protein, hemoglobin protein and many more.