This document discusses the structure and functions of proteins. It explains that proteins have primary, secondary, tertiary, and quaternary levels of structure which determine their function. Fibrous proteins have structural functions like collagen, while globular proteins have metabolic functions like hemoglobin. The primary structure is the sequence of amino acids in the polypeptide chain. Secondary and tertiary structures form due to bonding which creates the 3D shape of the protein, important for its specific function of interacting with other molecules.

1. The Structure of Proteins

21. Test for proteins