(a)[4]
One method for finding out which amino acids are present in a polypeptide chain is electrophoresis. Draw and label the apparatus used for electrophoresis.
(b(i))
Which factors decide the direction in which an amino acid travels?
(b(ii))[3]
Which factors determine how fast an amino acid moves?
(c(i))
Hydrogen atoms do not appear in images produced by X-ray crystallography. Explain why this happens.
(c(ii))[3]
Suggest and explain which atom in the cysteine molecule, $\text{H}_2\text{NCH(CH}_2\text{SH)CO}_2\text{H}$, would appear most clearly in X-ray crystallography.