Understanding Genetic Engineering: Cloning, Recombinant DNA, and Transgenic Organisms

1. KEY CONCEPT DNA sequences of organisms can be changed.

2. Genetic Engineering • Genetic engineering is the process of manipulating genes for practical purposes. Gene cloning is the process by which many copies of a specific gene are made each time the host cell reproduces.

3. Entire organisms can be cloned. • A clone is a genetically identical copy of a gene or of an organism. Fig. 4.1 - The cat named CC—for Copy Cat or Carbon Copy—is the first successful clone of a cat (right). The original cat is on the left.

4. Cloning occurs in nature. • bacteria (binary fission) • some plants (from roots) • some simple animals (budding, regeneration)

5. Mammals can be cloned through a process called nuclear transfer. • nucleus is removed from an egg cell • nucleus of a cell from the animal to be cloned is implanted in the egg

6. Cloning has potential benefits. • organs for transplant into humans • save endangered species • Cloning raises concerns. • low success rate • clones “imperfect” and less healthy than original animal • decreased biodiversity Apply: Given the opportunity, would you have a pet cloned? Explain your answer based on your knowledge of genetics.

7. (bacterial DNA) New genes can be added to an organism’s DNA. • Genetic engineering involves changing an organism’s DNA to give it new traits. • Genetic engineering is based on the use of recombinant DNA. • Recombinant DNA contains genes from more than one organism. Foreign DNA is inserted into plasmids to make recombinant DNA.

8. Bacterial plasmids are often used to make recombinant DNA. • plasmids are loops of DNA in bacteria • restriction enzymes cut plasmid and foreign DNA • foreign gene inserted into plasmid • Vector – bacteriophage, plasmid or other agent that transfers genetic material from one cell to another. Fig. 4.2 - A plasmid is a closed loop of DNA in a bacterium that is separate from the bacterial chromosome. (colored TEM; magnification 48,000 X)

9. Genetic engineering produces organisms with new traits. • A transgenic organism has one or more genes from another organism inserted into its genome. Fig. 4.3 – Plasmids are small rings of DNA used in genetic engineering. Foreign genes (blue, light blue, magenta, green) have been inserted into these plasmids (red). Colored TEM, magnification 29,000x Apply: Why are sticky ends important for making recombinant DNA? Summarize: How does genetic engineering rely on a shared genetic code?

10. Transgenic bacteria can be used to produce human proteins. • gene inserted into plasmid • plasmid inserted into bacteria • bacteria express the gene • Transgenic plants are common in agriculture. • transgenic bacteria infect a plant • plant expresses foreign gene • many crops are now genetically modified (GM) to resist frost, diseases and insects • corn and potatoes are common GM crops in the U.S.

11. Transgenic animals are used to study diseases and gene functions. • transgenic mice used to study development and disease • The first mouse used was called an oncomouse used to study cancer. • Other mice are used to study diabetes, brain function and development and sex determination. • gene knockout mice used to study gene function – by purposely “turning off” specific genes Fig. 4.4 - The knockout mouse (left) does not have a functional gene for a protein called leptin, which helps to control food intake. Researchers are using this type of mouse to study obesity. Infer: Why is it important that a transgenic trait is passed on the to transgenic organism’s offspring?

12. APPLICATION: Using Plasmids to Produce Insulin Animation: LINK

13. Scientists have concerns about some uses of genetic engineering. • possible long-term health effects of eating GM foods • possible effects of GM plants on ecosystems and biodiversity • - new pathogens might be created • - allergic reactions from donated foreign genes