Proteins
It has been estimated that about 18% of the human body is made up of protein. Like carbohydrates and fats, proteins are made up of the elements carbon (C), hydrogen (H) and oxygen (O) but they also contain nitrogen (N).
Keratin protein in hair
Keratin is a protein found in hair and skin. It is a fibrous protein and has a coiled structure similar to that of a telephone cord. The structure is described as an alpha helix. A human hair strand is made up of many alpha helices. This diagram shows three alpha helices interwoven to make a protofibril. Eleven protofibrils are bonded and coiled together to make a microfibril. Hundreds of these microfibrils are combined together into an irregular bundle called a macrofibril. These in turn are mixed with dead and living cells to make a complete strand of hair.
Download the Word file (see link below) to read this teacher resource, which provides information about proteins, specifically amino acids, peptide bond, peptides and proteins and types of proteins. It follows on from the article about macronutrients, giving more detail about this important group of energy-rich food substances.
