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Biology Biology Slide 1 of 18 Copyright Pearson Prentice Hall End Show 13 Changing the Living World EQ: How can genetics be used to change organisms? Slide 2 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Selective Breeding Selective Breeding Selective breeding allows only those organisms with desired characteristics to produce the next generation. Nearly all domestic animals and most crop plants have been produced by selective breeding. Slide 3 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Selective Breeding Humans use selective breeding to pass desired traits on to the next generation of organisms. Slide 4 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Selective Breeding Hybridization Hybridization is the crossing of dissimilar individuals to bring together the best of both organisms. Hybrids, the individuals produced by such crosses, are often hardier than either of the parents. Slide 5 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Selective Breeding Inbreeding Inbreeding is the continued breeding of individuals with similar characteristics. Inbreeding helps to ensure that the characteristics that make each breed unique will be preserved. Serious genetic problems can result from excessive inbreeding. Slide 6 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Increasing Variation Breeders increase the genetic variation in a population by inducing mutations. Slide 7 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Increasing Variation Mutations occur spontaneously, but breeders can increase the mutation rate by using radiation and chemicals. Breeders can often produce a few mutants with desirable characteristics that are not found in the original population. Slide 8 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Increasing Variation Producing New Kinds of Bacteria Introducing mutations has allowed scientists to develop hundreds of useful bacterial strains, including bacteria that can clean up oil spills. Slide 9 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Increasing Variation Producing New Kinds of Plants Mutations in some plant cells produce cells that have double or triple the normal number of chromosomes. This condition, known as polyploidy, produces new species of plants that are often larger and stronger than their diploid relatives. Polyploidy in animals is usually fatal. Slide 10 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World The Tools of Molecular Biology The Tools of Molecular Biology How do scientists make changes to DNA? Slide 11 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World The Tools of Molecular Biology Scientists use different techniques to: extract DNA from cells cut DNA into smaller pieces identify the sequence of bases in a DNA molecule make unlimited copies of DNA In genetic engineering, biologists make changes in the DNA code of a living organism. Slide 12 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World The Tools of Molecular Biology DNA Extraction DNA can be extracted from most cells by a simple chemical procedure. The cells are opened and the DNA is separated from the other cell parts. Cutting DNA Most DNA molecules are too large to be analyzed, so biologists cut them into smaller fragments using restriction enzymes. Each restriction enzyme cuts DNA at a specific sequence of nucleotides. Slide 13 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Separating DNA In gel electrophoresis, DNA fragments are placed at one end of a porous gel, and an electric voltage is applied to the gel. Making Copies Polymerase chain reaction (PCR) is a technique that allows biologists to make copies of genes. Small amounts of DNA can be multiplied making it easier to analyze Slide 14 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Transgenic Organisms Transgenic Organisms An organism described as transgenic, contains genes from other species. Genetic engineering has spurred the growth of biotechnology. Slide 15 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Transgenic Organisms Transgenic Microorganisms Transgenic bacteria produce important substances useful for health and industry. Transgenic bacteria have been used to produce: • insulin • growth hormone • clotting factor Slide 16 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Cloning Dolly and Bonnie Cloning A clone is a member of a population of genetically identical cells produced from a single cell. In 1997, Ian Wilmut cloned a sheep called Dolly. Slide 17 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Cloning Cloning Dolly Donor Nucleus Fused cell Egg Cell Embryo Cloned Lamb Foster Mother Copyright Pearson Prentice Hall Slide 18 of 18 End Show 13-1 Changing the Living World Cloning Cloning Dolly Slide 19 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Cloning Cloning Dolly Slide 20 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Cloning Cloning Dolly Slide 21 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Cloning Researchers hope cloning will enable them to make copies of transgenic animals and help save endangered species. Studies suggest that cloned animals may suffer from a number of genetic defects and health problems. Slide 22 of 18 Copyright Pearson Prentice Hall End Show