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Chapter 13- Genetic Engineering 13-1 *What do Goldendoodles, Labradoodles, and Puggles have in common? *All are a result of Selective Breeding- allowing only animals with desired characteristics to produce the next generation. Nearly all domestic animals (cats, horses, etc) and lots of crop plants have been produced by selective breeding *Important Historical Example: Luther Burbank (American) -developed disease-resistant Burbank potato -exported to Ireland to help fight potato blight and other diseases Hybridization- crossing similar organisms to bring together the best of both organisms Hybrids produced are often hardier than parents Inbreeding-continued breeding of individuals with similar characteristics good- maintaining certain characteristics bad- genetic defects- greater risk of recessive alleles joining and causing problems (ex: blindness, hip problems) Reminder: What is a mutation? -changes in genetic material -Mutations: -ultimate source of genetic variation. -inheritable changes in DNA -Breeders can increase genetic variation in a population by increasing mutations. -Mutations occur spontaneously -can increase rate by using radiation and chemicals 1 New Bacteria -small: millions can be treated with radiation or chemicals at same time -increases chance of producing useful mutant -ex: produced bacteria that digest oil – used to clean up oil spills New Kinds of Plants -Polyploidy-organism w/extra set of chromosomes -usually fatal in animals -Plants= larger and stronger -ex: crops- bananas and many citrus fruits 13-4 Genetic Engineering Genetic Engineering makes it possible to transfer DNA sequences (including whole genes) from 1 organism to another From animals to plants???? 1986- scientists isolated gene for luciferase -enzyme- makes fireflies glow -inserted into tobacco cells -plant glowed in dark -showed basic mechanisms of gene expression are shared by plants and animals Transgenic Organisms- contain genes from other species Biotechnology- manipulation of organisms to do practical things and to provide useful products Transgenic Microorganisms -Proteins: insulin, growth hormone, clotting factor -used to treat serious human diseases and conditions 2 -used to be expensive and rare -Bacteria transformed with human protein now produce these compounds -now cheaper and easier Transgenic Animals -used to study genes and improve food supply -mice- immune systems made to act like human immune systems -allows scientists to study effects of diseases -livestock (cattle, pigs)- some now have extra copies of growth hormone genes -grow faster; produce leaner meat (less fat) -Researchers trying to produce chickens resistant to bacteria that causes food poisoning. Transgenic Plants (also called Genetically Modified-GM) -Year 2000- 52% of soybeans and 25% corn grown in U.S. were transgenic or genetically modified (GM) -contain natural insecticide -resist chemicals –kill weeds w/out hurting crop -Rice with Vitamin A- important for human health -some countries rely on rice as main food = sure to get vitamin = improve health? Cloning -clone- member of a population of genetically identical cells produced from a single cell -bacterial clones- easy to grow; -multicellular clones (animals)- more difficult -1997- Dolly the sheep; scientist Ian Wilmut -figure 13-13 -cloning may help save endangered species -problems: genetic defects and health problems 3