Practise genetic-technology principle questions by tracing recombinant DNA steps, PCR amplification, gel electrophoresis, gene editing and molecular databases.
Recombinant human proteins can be used to treat disease.
Define the term recombinant DNA.
Insulin is composed of two polypeptide chains, the A chain and the B chain, that are linked by disulfide bonds.
Variations in amino acid sequence occur:
- in the insulin molecules of different animals
- in new versions of human insulin that have been engineered to control blood glucose concentration more effectively than normal recombinant human insulin. These new versions of human insulin are called analogues.
Table 4.1 shows the amino acid positions where variation occurs in different animal and human analogue insulin molecules. The dashes indicate a missing amino acid.
Suggest ways in which analogue insulin molecules can be produced by genetic engineering techniques.
Information about amino acid and nucleotide sequences is stored in computer databases.
Outline the advantages of using databases of nucleotide sequences to investigate evolutionary relationships between species.
Fig. 5.1 shows the area of land that was used to grow genetically modified (GM) crops in the USA, Brazil, India and China from 2004 to 2015.
Fig. 5.1
Describe the difference between Bt maize and non-GM maize that explains why Bt maize is resistant to insects.
Factor VIII can be made as a recombinant human protein.
The gene that codes for human factor VIII can be synthesised from messenger RNA purified from human liver cells.
Name the enzyme that uses messenger RNA as a template to produce complementary DNA.
Outline two sources, other than messenger RNA, from which genes can be obtained for genetic engineering.
The gene that codes for human factor VIII can be transferred into mammalian cells in tissue culture.
Explain why a promoter also needs to be transferred into the mammalian cells so that human factor VIII can be synthesised.