TF Proteins are the most diverse macromolecule class in the

T/F: Proteins are the most diverse macromolecule class in the world. How many amino acids long is an average protein? What type of bond is broken and reformed when someone straightens their curly hair?

Solution

The number of amino acids in a protein is important for determining the tertiary structure of protein as it improves the chances of including multiple secondary structures in the protein. The average protein length is different with different domain of the three domain classification (eukaryotes, prokaryotes and archaea). The average protein for the archaeal species are 283 aa amino acids (aa), 320 aa for bacteria and 472 aa for eukaryotes. The hair follicle with an oval shape gives the hair its curly shape. Also, hair is made up of a protein called keratin. Keratin contains many sulfur containing amino acids (cysteine) which forms the covalent disulfide bonds (S-S) with adjacent chain of keratin contributing to curling between this bonds. Also, weak hydrogen bonds are formed between the chains of keratin proteins and these bonds are easily affected by water.These above bonds makes the hair strong as well as makes it sure that the shape of the hair remains the same due to the fixed position of keratin. When hair is straightened temporarily, heat is applied by the plates of the iron which causes the weak hydrogen bonds to break and it is reformed when moisture (humidity, water) is locked in again into the hair. (For the covalent disulphide bonds to be broken, more severe heat is to be applied, is permanent and it is not affected by water).