There are 20 common amino acids in all organisms that differ only in their side group (R)
Amino acids join together through a condensation reaction, removing a water molecule between the carboxyl group of one amino acid and an amine group of another which overall forms a peptide bond
Dipeptides are 2 amino acids joined together
Polypeptides are manyaminoacids joined together
The primary structure is the sequence of amino acids in a polyepeptide chain, joined together by peptide bonds
The secondary structure s the folding of polypeptide chains e.g, alpha helix or beta pleated sheets, due to the hydrogen bonding between the amino acids between the NH group of one amino acids and the C=O group of another
The tertiary structure of a protein is the 3D folding of polypeptide chain, due to interactions between amino acids and R groups, which forms hydrogen bonds, ionic bonds and disulfide bridges
The quaternary structure is when there is more than onepolypeptide chain which is formed by interactions between polypeptides
The test for proteins is:
Add Biuret reagent which is sodium hydroxide + copper (II) sulphate
A positive result would show blue to purple, indicating peptide bonds
