State the meaning of recombinant DNA.
During the period from the 1920s to the 1970s, insulin taken from animal bodies was used to treat diabetes. From the 1970s onwards, recombinant human insulin replaced it. Explain the advantages of using recombinant human insulin to treat people with diabetes.
Insulin consists of two polypeptide chains, the A chain and the B chain, linked together by disulfide bonds. Amino acid sequence differences occur in the insulin molecules of different animals; they also occur in modified forms of human insulin that have been engineered to regulate blood glucose concentration more effectively than normal recombinant human insulin. These modified forms of human insulin are called analogues.
Cats with diabetes can be treated successfully using insulin injections. Cat insulin is not available, but vets can select from the other insulin types shown in Table 4.1. Identify the type of insulin that is most suitable for treating cats.
Suggest ways in which analogue insulin molecules can be produced by genetic engineering techniques.
Information about amino acid and nucleotide sequences is kept in computer databases. Outline the advantages of using databases of nucleotide sequences to investigate evolutionary relationships between species.