Amino Acids

Question 1

What is the term used for molecules with basic and acidic properties?

Answer 1

Zwitterions

Question 2

What functional groups do amino acids contain that make them zwitterions?

Answer 2

Carboxyl group (-COOH) and an amino group (-NH₂)

Question 3

Describe the general structure of an amino acid

Answer 3

Central carbon attached to an amino group, a carboxyl group, a hydrogen and an ‘R’ group.

Question 4

Describe a zwitterion in neutral conditions

Answer 4

• 2 charges that are different

- Attracted to each other

Question 5

What happens to amino acids in acidic conditions?

Answer 5

• All COOH groups remain the same

- All NH₂ groups become NH₃⁺

Question 6

What happens to amino acids in alkaline conditions?

Answer 6

• All COOH groups become COO⁻

- All NH₂ groups remain the same

Question 7

Describe electrophoresis and its results

Answer 7

• Damp filter paper with +ve and -ve elecrodes attached as crocodile clips
• Spray with toxic ninhydrine and a purple brown spot appears
• If amino acid is dissolved in acid, it is +ve and will go to negatively charged electrode
• If amino acid is dissolved in alkali, it is -ve and will go to positively charged electrode