What is the structure of a protein?

Proteins are one of the most important organic substances that make up living organisms. By their chemical nature, they are biopolymers, the monomers of which are amino acids. Amino acids are linked together using peptide bonds. The type and properties of the protein depend on WHAT amino acids and in what QUANTITY are included in the protein, as well as on the ORDER of their combination. Each protein molecule has a primary, secondary and tertiary structure. And some, like hemoglobin, have a quaternary structure.