Gene technologyEdexcel A-Level Biology B: Mind map

Exam questions on Gene technology

1. Scientists want bacteria to make human insulin. They cut the human insulin gene out of human DNA and cut a bacterial plasmid with the same restriction endonuclease. The enzyme cuts at a specific recognition sequence and leaves short single-stranded overhangs at each end of the cut DNA.
   Explain why the same restriction endonuclease is used to cut both the human DNA and the plasmid.2 marks
2. A plasmid carries two antibiotic resistance genes, one for ampicillin and one for tetracycline. A human gene is inserted into the middle of the tetracycline resistance gene. Bacteria are mixed with the plasmids and spread on agar containing ampicillin (the master plate). Colonies are then transferred by pressing a sterile velvet pad first on the master plate and then on agar containing tetracycline (the replica plate), keeping the positions of the colonies.
   Explain why bacteria containing a plasmid without the human gene grow on both plates.2 marks
3. Researchers have identified a human gene, called gene X, which they think is involved in the development of the heart. They produce knockout mice in which gene X has been inactivated in every cell and compare the mice with normal mice.
   Explain how the knockout mice can be used to find out the function of gene X.3 marks