State the function of each of these enzymes in making rDNA that carries the gene for human insulin: reverse transcriptase; DNA polymerase; restriction enzyme; DNA ligase.
Summarise the role of insulin in a healthy human.
Describe and explain one advantage of treating diabetics with human insulin made by rDNA technology.
rDNA technology can also be used to make insulin with a slightly altered structure compared with human insulin. The effect of the altered structure can then be tested. Equal quantities of two insulins, both produced by E. coli, were compared in healthy, non-diabetic subjects: human insulin and insulin X, in which lysine and proline had been swapped. Lysine has a hydrophilic R group and proline has a hydrophobic R group. The results of the investigation are shown in Fig. 3.1.
Using Fig. 3.1, describe how the activity of human insulin and insulin X differs.
Suggest how swapping the positions of two amino acids in the insulin molecule could lead to differences in activity.