Genetic Engineering 1 of 27 Boardworks Ltd 2012

Transcription

1 Genetic Engineering 1 of 27 Boardworks Ltd 2012

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3 What is genetic engineering? 3 of 27 Boardworks Ltd 2012 DNA of living organisms can be modified by the insertion or removal of specific sections of DNA called genes. Changing the DNA of an organism to modify its characteristics is known as genetic engineering. Often, a foreign gene is inserted into an organism s genome. This will result in the expression of the new gene, coding for the desired, valuable product. For example, yeast can be genetically engineered to produce vaccines for human diseases.

4 Using micro-organisms 4 of 27 Boardworks Ltd 2012

5 Advantages of micro-organisms 5 of 27 Boardworks Ltd 2012 There are some advantages in genetically engineering micro-organisms so they express a desired product: there are fewer ethical issues associated with their use they can be grown in fermenters to produce the desired protein rapidly and on a large scale. Pharmaceutical companies use micro-organisms in the large scale manufacture and development of a range of medicines, including antibiotics.

6 Using genetically modified bacteria 6 of 27 Boardworks Ltd 2012

7 Transgenics 7 of 27 Boardworks Ltd 2012 When an organism has a foreign gene inserted into its genome, it is called a transgenic organism. Foreign DNA, including DNA from humans, can be inserted into micro-organisms, plants or animals. For example, the gene for a human antibody can be introduced into goats. The antibody is then expressed in the goat s milk, where it can be purified and used to treat diseases.

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9 How does genetic engineering work? 9 of 27 Boardworks Ltd 2012 Genetic engineering involves four main stages. Stage Example 1. Isolate and replicate the gene coding for the desired product. 2. Put the gene into a suitable vector (a virus or plasmid). 3. Insert the gene into the target cell using the vector. 4. Replicate the new organism and identify the modified organisms. What is the product in this example? antigen for hepatitis B hepatitis B virus yeast yeast culture in fermenters Hepatitis B vaccine

10 The science of genetic engineering 10 of 27 Boardworks Ltd 2012

11 Genetically engineering bacteria 11 of 27 Boardworks Ltd 2012

12 Selecting the modified bacteria 12 of 27 Boardworks Ltd 2012

13 Identifying modified cells 13 of 27 Boardworks Ltd 2012 Fluorescent markers and enzymes markers are used to identify cells that have taken up the desired gene. A gene from a jellyfish that makes a protein called green fluorescent protein (GFP) can be used. The desired gene is inserted into the GFP gene, disrupting its expression. The modified cells will therefore not fluoresce. A desired gene could also be inserted into a gene coding for lactase. The presence of lactase results in a characteristic colour change. Modified cells will not cause this colour change.

14 True or false? 14 of 27 Boardworks Ltd 2012

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16 How else is genetic engineering useful? 16 of 27 Boardworks Ltd 2012 Genetic engineering is also used to create transgenic organisms which have a novel, desired feature, such as genetically-modified (GM) crops. These include: pest-resistant crops such as insect-resistant crops that have been engineered to produce a bacterial toxin that kills a specific pest. herbicide-resistant crops disease-resistant crops such as frost-resistant lettuces. crops with increased health benefits. GM lettuce non-gm lettuce

17 How to genetically modify plants 17 of 27 Boardworks Ltd 2012 The bacteria, Agrobacterium tumefaciens, is a pathogen that causes the growth of tumours in plants. The bacterial cells contain a tumourinducing, or Ti plasmid, which they inject into plant cells. Harmful genes become incorporated into the plant s DNA, causing excessive cell growth. Scientists can replace the diseasecausing genes in the Ti plasmid with useful genes. This means that the Ti plasmid can be used as a vector to produce transgenic plants.

18 Making transgenic plants 18 of 27 Boardworks Ltd 2012

19 Insect resistance 19 of 27 Boardworks Ltd 2012 Bacteria called Bacillus thuringiensis (Bt), produce toxins that are biological pesticide. Bt genes can be isolated to create genetically-modified plants with insect resistance. The advantages include: the toxin only affects very specific species of insects reduces use of synthetic pesticides. However, insects may acquire resistance to all pesticides containing the Bt toxin. Also, the long-term effect of eating Bt crops on human health remains uncertain.

20 Should GM crops be allowed? 20 of 27 Boardworks Ltd 2012

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22 The GM debate 22 of 27 Boardworks Ltd 2012

23 Opinions on GM organisms 23 of 27 Boardworks Ltd 2012

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25 Glossary 25 of 27 Boardworks Ltd 2012

26 Anagrams 26 of 27 Boardworks Ltd 2012

27 Multiple-choice quiz 27 of 27 Boardworks Ltd 2012