Question 18M.3.sl.TZ1.6
| Date | May 2018 | Marks available | [Maximum mark: 6] | Reference code | 18M.3.sl.TZ1.6 |
| Level | sl | Paper | 3 | Time zone | TZ1 |
| Command term | Deduce, Draw, Outline, State | Question number | 6 | Adapted from | N/A |
Insulin was the first protein to be sequenced. It was determined that the end of one chain had the primary structure Phe–Val–Asn–Gln.
Draw the structural formula of a dipeptide containing the residues of valine, Val, and asparagine, Asn, using section 33 of the data booklet.
[2]
correct structures of Val AND Asn
correct amide link
[2 marks]
Deduce the strongest intermolecular forces that would occur between the following amino acid residues in a protein chain.
[2]
Phenylalanine and valine:
London/dispersion/instantaneous induced dipole-induced dipole forces
OR
permanent dipole-induced dipole «interactions»
Glutamine and asparagine:
hydrogen bonds
Do not accept dipole-dipole interactions.
[2 marks]
Paper chromatography can be used to identify the amino acids in insulin.
State the name of the process used to break down the insulin protein into its constituent amino acids.
[1]
hydrolysis
[1 mark]
Outline how the amino acids may be identified from a paper chromatogram.
[1]
compare Rf with known amino acids
OR
compare distance moved with known amino acids
Accept “from Rf”.
[1 mark]