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B1b: 7 Genetic engineering – cut and paste! Here is a description of how bacteria can be genetically engineered to produce human insulin. Insulin is needed for the treatment of diabetics. Many bacterial cells contain rings of DNA, which are called plasmids. These plasmids can be used in genetic engineering. Scientists have been able to identify which human gene controls the production of insulin. This gene is ‘cut out’ from human DNA by special ‘chemical scissors’ called a restriction enzyme. This same enzyme can cut open a plasmid. The human insulin gene is then inserted into the plasmid. Another enzyme, called a ligase, joins the two ends of the insulin gene to the cut ends of the plasmid. The plasmid has been recombined with the insulin gene. It is now called a recombinant plasmid, or recombinant DNA. The recombinant plasmid now has to be put back into the bacterial cell. This can be done by, literally, shocking the bacterium with a small, short electric shock. This makes very small, temporary, holes in the bacterium’s cell wall. The recombinant plasmids quickly pass through these holes before they close up again. Bacteria that contain recombinant DNA will start to produce lots of insulin, but only if they are given the right conditions. First task Draw a flow chart that shows the stages of making a bacterium that contains recombinant DNA. Is genetic engineering ethical? In recent years lots of different plants and animals have been genetically engineered. This has made them more useful to us. Here is a table of some of these plants and animals. How have they been made more useful? Examples Make chemicals that stop insects eating them • • • • • • • • • • • • • • • • • • • • Make them resistant to herbicides Make them resistant to virus infections Used in the production of medicines Make them grow more quickly Some varieties of apples Cotton plants Maize Tomatoes Cabbage Oilseed rape Peanuts Potatoes Cucumbers Melons Papaya Tobacco Cattle Goats Mice Sheep Carp (a type of fish) Cattle Pigs Salmon B1b: 7 Evolution and environment – continued Second task Explain how each reason listed in the table is directly useful to us. _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ _________________________________________________________________________________________________________ B1b: 7 Answers to Worksheets Worksheet B1b: 7 First task: Second task: Pupils to consider each reason why genetically engineered organisms are useful to us and then explain it: Make chemical which stop insects eating them: Greater productivity Make them resistant to herbicides: fields can be sprayed to kill weeds with no danger of harming crop plants Resistant to viral infections: Greater productivity Used in the production of medicines: Could be seen as more natural rather than producing medicines in a lab They grow more quickly: faster productivity and hence bigger profits B1b: 7 Technician’s Notes Starter activity Resources: newspaper cutting describing the destruction of a GM crop by protestors