Topic 2: Amino acids and Peptides

Which of the following amino acids has a side chain with a pKa around 4.1?

• Lysine

• Aspartic acid

• Histidine

• Arginine

What is the isoelectric point for the amino acid Tryptophan?

pKa1 = 2.38

pKa2 = 9.39

• 2.38

• 7.07

• 5.89

• 9.39

Which amino acid has a molecular weight of approximately 89 Da?

• Glycine

• Alanine

• Serine

• Valine

What is the correct ionization state of histidine at pH = 1?

• -1

• 0

• +1

• +2

Which amino acid is most likely to be found in the interior of a protein due to its hydrophobic nature?

• Glutamine

• Leucine

• Serine

• Lysine

What is the reaction that describes the formation of a peptide bond?

• Hydrolysis

• Condensation

• Oxidation

• Reduction

Which amino acid has a side chain that can form disulfide bonds?

• Methionine

• Cysteine

• Proline

• Histidine

Which of the following amino acids has a basic side chain?

• Glutamic acid

• Arginine

• Asparagine

• Phenylalanine

This is the structure of GABA.

Is GABA an amino acid?

• Yes

• No

• Maybe

• I’m not sure

Which of the following is a characteristic feature of the amino acid proline that distinguishes it from other standard amino acids?

• It contains a sulphur atom in its side chain.

• It has a secondary amine group.

• It is the only amino acid with a hydroxyl group in its side chain.

• It has an aromatic ring in its side chain.