2. 9 There are several ways in which genes from one organism can be inserted into a different organism They can be coated on to microscopic gold particles and ‘fired’ into the cells They can be delivered by viruses They can be transmitted by using structures, called plasmids, present in bacteria For example, the human gene for making insulin can be transferred to bacteria, which are then allowed to reproduce in a culture medium from which the insulin can be extracted Plasmids
3. A bacterium 10 in addition to a loop of DNA… …bacteria also contain numerous rings of DNA called plasmids cell wall cytoplasm 0.001mm cell membrane the plasmids can be extracted and used for genetic engineering
4. 11 Inserting a gene plasmid human DNA strand restriction enzyme cuts plasmid the same restriction enzyme cuts the insulin gene out of the human DNA insulin gene the insulin gene is inserted into the plasmid
5. 12 The recombinant plastids are inserted into a bacterium * the insulin gene makes the bacterium produce insulin Recombinant plastids
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8. 15 Genetic engineering does not always have to involve gene transfer between unrelated organisms Genes in a single organism can be modified to improve their characteristics or their products A gene for the production of ß carotene (a precursor of Vitamin A) has been introduced to rice to benefit countries where rice is the staple diet and Vitamin A deficiencies are common* The next slide shows tomatoes which have been genetically modified to suppress production of an enzyme which causes the fruit to soften as it ripens. This improves the keeping qualities Applications