Proteins

Question 1

Describe the biochemical test for lipids.

Answer 1

Add ethanol to test substance and shake, then pour into water. Positive result = milky emulsion.

Question 2

Name the chemical bond that is formed between two amino acids during a condensation reaction

Answer 2

peptide bond

Question 3

Describe the biochemical test for proteins, including a negative and positive test result.

Answer 3

Add sodium hydroxide solution to test sample, then add copper sulfate solution. Negative result = solution stays blue.
Positive result = turns purple.

Question 4

Describe the primary structure of a protein.

Answer 4

Sequence of amino acids

Question 5

Describe the secondary structure of a protein.

Answer 5

chain coils into an alpha helix or folds into a beta sheet - held in place by hydrogen bonds.

Question 6

Name the three chemical bonds found in the tertiary structure of a protein.

Answer 6

Hydrogen bonds, ionic bonds and disulphide bridges

Question 7

Describe the quaternary structure of a protein.

Answer 7

Two or more polypeptide chains held together by bonds.

Question 8

Name two examples of proteins with quaternary structures.

Answer 8

Insulin, Haemoglobin, collagen, antibodies