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Arrangements Forensic uses • DNA profiling: – relies on repetitive, – hypervariable DNA and not genes per se. • Stages involved: – – – – – DNA isolation, restriction enzyme digestion, gel electrophoresis, blotting DNA onto a filter, hybridisation with a probe. • Use of single locus probe. Learning Objective • To explain how DNA technology has been adapted foe use by forensic scientists. Forensic Uses • Out with the old – DNA fingerprinting • In with the new – DNA profiling • A sample of DNA from a suspect can be matched with that of a reference sample. • PCR is used to amplify minute samples of DNA DNA profiling • Uses minisatellite regions – Variable number tandem repeats (VNTRs) • Steps – – – – – DNA isolation, restriction enzyme digestion, gel electrophoresis, blotting DNA onto a filter, hybridisation with a probe Probes • Binds to a specific base sequence on target fragments – Multi-locus probes • More complex patterns – Single locus probes DNA profiling • Short tandem repeats (STRs) – A.k.a. microsatellites – PCR based technique • Uses fluorescent labels and automated DNA detection equipment. Arrangements Agriculture - Transgenic plants • Transgenic plants are engineered by using a plasmid from Agrobacterium. – Foreign DNA carrying genes for the desired characteristics inserted into bacterial plasmid. – Plant cell protoplasts incubated with bacteria containing genetically engineered plasmid in medium which allows only those plant cells which have taken up the foreign DNA to grow. – Illustrate application by transgenic tomato plants: • gene for bacteria toxin transferred to plants resulting in effective protection from insect damage. Arrangements Agriculture - Transgenic plants • Moral and ethical issues relating to the use of transgenics. Arrangements Agriculture - BST • Production of bovine somatotrophin (BST) by genetic engineering and its use in cattle. – Gene for BST cloned into a bacterial system. – Product purified and administered to cattle by injection or in feed. – BST increases milk production. Learning Objective • To describe the production of transgenic or GM crops – Explain why a plasmid from Agrobacterium is used – Explain how foreign DNA is isolated and inserted into plasmids – Explain how plants containing recombinant DNA can be grown and expanded – Describe the production of transgenic tomato plants • To list some potential uses of GM plant technology Learning Objective • To describe the production of BST • To describe the use of BST Keywords - Activity • Find the meaning of the following words – – – – – – Microinjection Transfection Transformation Transgene Transgenic DNA cloning DNA technology and Agriculture • Two uses of DNA technology in agriculture – Production of Transgenic organisms • Transgenic plants – Production of growth hormones using recombinant DNA methods. • Bovine growth hormone Transgenic plants • Requirements – Suitable vector – Mechanism for regenerating whole plants • Ti Plasmid – Found in soil bacterium Agrobacterium tumefaciens (crown gall disease) Preparation of Ti plasmid • The Ti plasmid can integrate DNA into plant cell genome • Stages – – – – – – Remove tumour inducing genes Insert gene and marker Culture plasmid and protoplasts Stimulate cell wall development Callus formation Seedling formation Transgenic plants • FLAVR SAVR tomato – Production of ethylene is inhibited to delay the ripening process. • Insect resistance – Insert a gene from Bacillus thuringiensis that produces an insecticidal protein • Introduction of nitrogen fixation genes into non-leguminous plants. • Disadvantage of Ti-based vector system – Can only work for dicotyledonous plants – A lot of crops are monocotyledonous. Bovine Growth Hormone bovine somatotrophin (BST) • BST – Increases milk yield by 10% – Improves weight gain in beef cattle by diverting resources to cell and protein production, suppresses the production of fatty deposits. Learning Objective • To list potential uses of DNA technology • To understand some of the moral and ethical issues raised by the production of transgenic plants and animals.
