Proteins Flashcards
What is the structure of an amino acid?
-amino group
-carboxylic acid group
-variable r group
How are proteins made?
-condensation reaction between amino acids, form peptide bond
-dipeptide only two amino acids, polypeptide contains 3 or more amino acids
Describe the primary structure of a protein
-order and number of amino acids in a protein
-initial sequence of amino acids and will determine the proteins function in the end
Describe the secondary structure of a protein
-shape of amino acids chains
-alpha helix or beta pleated sheet
-weak hydrogen bonds form between the amino group and the hydroxyl group
-most fibrous proteins have secondary structures (e.g collagen and keratin)
describe the tertiary structure of proteins
-3D shape is formed from further twisting and folding
-disulphide bonds between sulphide in cysteine amino acids
-ionic bonds between carboxyl and amino groups
-hydrogen bonds between between r groups
what are globular and fibrous proteins?
-globular are compact, e.g. enzymes
-fibrous are long thus form fibres, e.g. keratin
What is the test for proteins?
-biuret tests the presence of peptide bonds
-add equal volumes of sodium hydroxide and the sample to a test tube
-add a few drops of copper sulphate and mix
-positive test turns from blue to purple