A protein is a naturally occurring, extremely complex substance that is present in all living organisms. The human body contains thousands of different proteins, and they can be categorized according to their Structure, Properties, and Function. This short video will be about proteins according to their Structure. All Proteins are made up of amino acids. Humans can obtain proteins from plants, animals, and their products like meat, milk, and eggs. Simple proteins contain peptide chains composed of only amino acids and may be globular or fibrous in shape.