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Genetic Engineering 2 1.1 What is genetic engineering? • A technique in biotechnology • Used to transfer genes from one organism to another (need not be the same species) • Any organism that acquires a foreign gene is called a transgenic organism How is genetic engineering useful to man? 2.1 Transgenic casein cows Nine cloned cows in New Zealand are producing milk with an unusually high amount of protein. The herd has extra copies of genes for two forms of casein, the major protein in milk and the main component of curd. 2.2 Transgenic carnations Wilt-proof flowers, last for three weeks after cutting. Normal flowers wilt after three days 2.3 Transgenic salmon Shortened production cycles, and eleven times heavier than nontransgenic salmon 2.4 Transgenic pea plants Weevil proof peas 2.5 Cloning 2.6 Genetic engineering in medicine • Many inherited diseases are caused when the body cannot make a particular protein • Haemophilia. – Haemophiliacs cannot make the protein Factor 8 which helps clotting. • Diabetes – Diabetics cannot make the protein insulin. • Genetic engineering can be used to make large amounts of these proteins. 3.1 How does genetic engineering work? • • • • • • Identifying the specific gene Isolating the gene Inserting the gene into a vector Inserting the vector into a host cell Multiplying the host cell Synthesizing the product by the host cell • Separating the product from the host cell • Purifying the product 3.2 Important terms in genetic engineering • Restriction enzymes – To cut DNA at specific points, making small fragments • DNA ligase – To join DNA fragments together • Vectors – To carry DNA into cells and ensure replication • Plasmids – Common kind of vector • Transgenic bacteria 3.3 Activity : DNA Recombination • Simulate how genes are removed from one cell and inserted into another How EcoRI works? Genetic Engineering The process 1 2 3 Isolate the desired gene Insert the gene into the vector DNA Insert the recombinant DNA into bacteria Genetic Engineering Producing human insulin Background: Type 1 diabetes is caused by the inability of the islets of Langerhans to produce sufficient insulin. • Mass production of human insulin for type 1 diabetes patients was made possible through the use of genetic engineering. • The human insulin gene is transferred to bacterial cells that are able to express the gene. The product (insulin) can then be harvested. • https://www.youtube.com/watch?v=AEINu CL-5wc Genetic Engineering insulin gene 1 • Obtain the human chromosome containing the insulin gene. How the human insulin gene is inserted into bacterial DNA Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 23 May 2017 17 Genetic Engineering insulin gene cut by restriction enzyme sticky end fragment of DNA containing the insulin gene 1 • Obtain the human chromosome containing the insulin gene. • Cut the gene using a restriction enzyme. This enzyme cuts the two ends of the gene to produce ‘sticky ends’. How the human insulin gene is inserted into bacterial DNA Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 23 May 2017 18 Genetic Engineering insulin gene cut by restriction enzyme sticky end fragment of DNA containing the insulin gene 1 • Obtain the human chromosome containing the insulin gene. • Cut the gene using a restriction enzyme. This enzyme cuts the two ends of the gene to produce ‘sticky ends’. • Each ‘sticky end’ is a single strand sequence of DNA bases. These bases can pair with complementary bases to form a double strand. Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. How the human insulin gene is inserted into bacterial DNA 23 May 2017 19 Genetic Engineering insulin gene plasmid cut by restriction enzyme sticky end fragment of DNA containing the insulin gene 2 • Obtain a plasmid from a bacterium. How the human insulin gene is inserted into bacterial DNA Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 23 May 2017 20 Genetic Engineering insulin gene plasmid sticky ends cut by restriction enzyme sticky end fragment of DNA containing the insulin gene cut by same restriction enzyme 2 • Obtain a plasmid from a bacterium. • Cut the plasmid with the same restriction enzyme. This produces complementary sticky ends. How the human insulin gene is inserted into bacterial DNA Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 23 May 2017 21 Genetic Engineering insulin gene plasmid sticky ends cut by restriction enzyme sticky end fragment of DNA containing the insulin gene cut by same restriction enzyme 3 • Mix the plasmid with the DNA fragment containing the insulin gene. How the human insulin gene is inserted into bacterial DNA Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 23 May 2017 22 Genetic Engineering plasmid insulin gene sticky ends cut by restriction enzyme sticky end fragment of DNA containing the insulin gene 3 • Mix the plasmid with the DNA fragment containing the insulin gene. cut by same restriction enzyme DNA ligase insulin gene inserted into plasmid • Add the enzyme DNA ligase to join the insulin gene to the plasmid. How the human insulin gene is inserted into bacterial DNA Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 23 May 2017 23 Genetic Engineering plasmid insulin gene sticky ends cut by restriction enzyme sticky end fragment of DNA containing the insulin gene 4 • Mix the plasmid with E. coli bacteria. cut by same restriction enzyme DNA ligase insulin gene inserted into plasmid bacterial DNA E. coli How the human insulin gene is inserted into bacterial DNA Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 23 May 2017 24 Genetic Engineering plasmid insulin gene sticky ends cut by restriction enzyme sticky end fragment of DNA containing the insulin gene 4 • Mix the plasmid with E. coli bacteria. • Apply temporary heat or electric shock. This opens up pores in the cell surface membrane of each bacterium for the plasmid to enter. cut by same restriction enzyme DNA ligase insulin gene inserted into plasmid bacterial DNA E. coli plasmid enters the bacterium plasmid bacterial DNA How the human insulin gene is inserted into bacterial DNA trangenic bacterium Copyright © 2006-2011 Marshall Cavendish International (Singapore) Pte. Ltd. 23 May 2017 25 Questions to ask • • • • Why use bacterial plasmid? Why use a bacterial cell? Can we use a virus? Can the DNA mutate? • How viruses work? • https://www.youtube.com/watch? v=Rpj0emEGShQ Genetic Engineering Activity Have you heard of the term ‘designer babies’? Find out more about more about designer babies on the Internet and prepare a presentation on it. 4.1 What are the advantages of genetic engineering? • Improves product quality and quantity • Generates cheaper products • Products grown or extracted from unconventional sources 2.2 Genetic engineering: Some disadvantages • Effect on the food web unknown • Long-term side effects unknown • Is it ethical?
