B1.2 Proteins

Question 1

primary structure of proteins

Answer 1

order and sequence of amino acids in a protein

Question 2

secondary structure of a protein

Answer 2

alpha helix/beta pleated sheet, weak hydrogen bonds hold them together

Question 3

tertiary structure

Answer 3

3D shape of the protein: disulfide bridges-between sulfur in R group of amino acid CYSTEINE, very strong; ionic bond(easily broken by pH and weaker than disulfide); hydrogen bonds(numerous and easily broken); hydrophobic interactions(between 2 non-polar chains)

Question 4

globular proteins

Question 5

fibrous proteins

Question 6

what does Biuret test for?

Answer 6

presence of peptide bonds in a protein and to detect proteins in food

Question 7

describe the test for proteins

Answer 7

sample in test tube and add sodium hydroxide, add dilute copper sulfate solution and mix, purple colour indicates presence of peptide bond hence a protein, if it stays blue it’s negative