7.2 Lesson 2: Hair Structure: Overview
- Hair is made mostly of proteins, which account for about 85 to 90 percent of its structure. The main type of protein in the hair is called keratin, which is made up mainly of the amino acids, cysteine, cystine, glutamic acid, and serine. The remaining 10 percent or so of the hair fiber is made up of melanin (the pigment that gives hair its color), fats and oils, trace metals, and water.
- A typical hair strand is composed of 50% carbon, 20% oxygen, 17% nitrogen, 6% hydrogen, and 5% sulfur. Trace amounts of magnesium, arsenic, iron, chromium and other metals and minerals are also present in the hair.
- Keratin is a tough, insoluble protein and is the chief structural constituent of hair, skin, and nails. There are two main types of keratin, alpha-keratin (found in mammalian hair and nails) and beta-keratin (found in bird feathers and reptile scales). There have been more than 50 different human keratins identified with gene analysis.
- Keratin proteins are shaped like alpha-helixes (helical shaped polypeptides held together by hydrogen bonds) that build into protofibrils, microfibrils, and macrofibrils (see Chapter 3 > Unit 2 > Lesson 3 to review chemical bonds).
