KEY CONCEPT DNA sequences of organisms can be changed.

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.

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.

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

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

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.

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. (bacterial DNA) Foreign DNA is inserted into plasmids to make recombinant DNA.

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)

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?

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.

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?

APPLICATION: Using Plasmids to Produce Insulin Animation: LINK

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