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13-1 Changing the Living World Slide 1 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Selective Breeding What is the purpose of selective breeding? 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 Slide 7 of 18 Copyright Pearson Prentice Hall End Show 13-1 Changing the Living World Increasing Variation Increasing Variation Why might breeders try to induce mutations? Slide 8 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 9 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 10 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 11 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. Except in the case of the Red Viscacha Rat Slide 12 of 18 Copyright Pearson Prentice Hall End Show 13-1 Click to Launch: Continue to: - or - Slide 13 of 18 End Show Copyright Pearson Prentice Hall 13-1 The usual function of selective breeding is to produce organisms that a. are better suited to their natural environment. b. have characteristics useful to humans. c. can compete with other members of the species that are not selected. d. are genetically identical. Slide 14 of 18 End Show Copyright Pearson Prentice Hall 13-1 Crossing a plant that has good diseaseresistance with a plant that has a good foodproducing capacity is an example of a. inbreeding. b. hybridization. c. polyploidy. d. crossing over. Slide 15 of 18 End Show Copyright Pearson Prentice Hall 13-1 New species of plants that are larger and stronger are a result of a. monoploidy. b. diploidy. c. polyploidy. d. triploidy. Slide 16 of 18 End Show Copyright Pearson Prentice Hall 13-1 The function of inbreeding is to produce organisms that a. are more genetically diverse. b. are much healthier. c. are genetically similar. d. will not have mutations. Slide 17 of 18 End Show Copyright Pearson Prentice Hall 13-1 Increasing variation by inducing mutations is particularly useful with a. animals. b. bacteria. c. plants. d. fungi. Slide 18 of 18 End Show Copyright Pearson Prentice Hall END OF SECTION Biology Biology Slide 20 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Slide 21 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology The Tools of Molecular Biology How do scientists make changes to DNA? Slide 22 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology Scientists use their knowledge of the structure of DNA and its chemical properties to study and change DNA molecules. Slide 23 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA 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 Slide 24 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology In genetic engineering, biologists make changes in the DNA code of a living organism. Slide 25 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA 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. Slide 26 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology Cutting DNA Most DNA molecules are too large to be analyzed, so biologists cut them into smaller fragments using restriction enzymes. Slide 27 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology Each restriction enzyme cuts DNA at a specific sequence of nucleotides. Recognition sequences DNA sequence Restriction enzyme EcoR I cuts the DNA into fragments Sticky end Slide 28 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology A restriction enzyme will cut a DNA sequence only if it matches the sequence precisely. Recognition sequences DNA sequence Restriction enzyme EcoR I cuts the DNA into fragments Sticky end Slide 29 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology 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. When the power is turned on, the negativelycharged DNA molecules move toward the positive end of the gel. Whoa! We did this!!!!!! Slide 30 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology Gel electrophoresis can be used to compare the genomes of different organisms or different individuals. It can also be used to locate and identify one particular gene in an individual's genome. Slide 31 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology Power source DNA plus restriction enzyme Longer fragments Mixture of DNA fragments Gel Gel Electrophoresis Copyright Pearson Prentice Hall Shorter fragments Slide 32 of 32 End Show 13-2 Manipulating DNA First, restriction enzymes cut DNA into fragments. The Tools of Molecular Biology DNA plus restriction enzyme The DNA fragments are poured into wells on a gel. Mixture of DNA fragments Gel Electrophoresis Copyright Pearson Prentice Hall Gel Slide 33 of 32 End Show 13-2 Manipulating DNA The Tools of Molecular Biology Power source An electric voltage is applied to the gel. This moves the DNA fragments across the gel. The smaller the DNA fragment, the faster and farther it will move across the gel. Gel Electrophoresis Slide 34 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology Based on size, the DNA fragments make a pattern of bands on the gel. These bands can then be compared with other samples of DNA. Longer fragments Shorter fragments Gel Electrophoresis Slide 35 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Using the DNA Sequence Using the DNA Sequence Knowing the sequence of an organism’s DNA allows researchers to study specific genes, to compare them with the genes of other organisms, and to try to discover the functions of different genes and gene combinations. Slide 36 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Using the DNA Sequence Reading the Sequence In DNA sequencing, a complementary DNA strand is made using a small proportion of fluorescently labeled nucleotides. Slide 37 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA DNA Sequencing Using the DNA Sequence DNA strand with unknown base sequence Dye molecules DNA fragments synthesized using unknown strand as a template Slide 38 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Using the DNA Sequence Each time a labeled nucleotide is added, it stops the process of replication, producing a short color-coded DNA fragment. When the mixture of fragments is separated on a gel, the DNA sequence can be read. Slide 39 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Using the DNA Sequence Base sequence as “read” from the order of the dye bands on the gel from bottom to top: TGCAC Electrophoresis gel Slide 40 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Using the DNA Sequence Cutting and Pasting Short sequences of DNA can be assembled using DNA synthesizers. “Synthetic” sequences can be joined to “natural” sequences using enzymes that splice DNA together. Slide 41 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Using the DNA Sequence These enzymes also make it possible to take a gene from one organism and attach it to the DNA of another organism. Such DNA molecules are sometimes called recombinant DNA. Slide 42 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Using the DNA Sequence Making Copies Polymerase chain reaction (PCR) is a technique that allows biologists to make copies of genes. A biologist adds short pieces of DNA that are complementary to portions of the sequence. Slide 43 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Using the DNA Sequence DNA is heated to separate its two strands, then cooled to allow the primers to bind to single-stranded DNA. DNA polymerase starts making copies of the region between the primers. • PCR song: http://www.youtube.com/watch?v=7uafUVNkuzg • DNA Song: http://www.youtube.com/watch?v=bF2QalUj1Y Slide 44 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Using the DNA Sequence Polymerase Chain Reaction (PCR) DNA heated to separate strands DNA polymerase adds complementary strand DNA fragment to be copied PCR cycles 1 DNA copies 1 2 2 3 4 4 8 5 etc. 16 etc. Slide 45 of 32 Copyright Pearson Prentice Hall End Show 13-2 Click to Launch: Continue to: - or - Slide 46 of 32 End Show Copyright Pearson Prentice Hall 13-2 Restriction enzymes are used to a. extract DNA. b. cut DNA. c. separate DNA. d. replicate DNA. Slide 47 of 32 End Show Copyright Pearson Prentice Hall 13-2 During gel electrophoresis, the smaller the DNA fragment is, the a. more slowly it moves. b. heavier it is. c. more quickly it moves. d. darker it stains. Slide 48 of 32 End Show Copyright Pearson Prentice Hall 13-2 The DNA polymerase enzyme Kary Mullis found in bacteria living in the hot springs of Yellowstone National Park illustrates a. genetic engineering. b. the importance of biodiversity to biotechnology. c. the polymerase chain reaction. d. selective breeding. Slide 49 of 32 End Show Copyright Pearson Prentice Hall 13-2 A particular restriction enzyme is used to a. cut up DNA in random locations. b. cut DNA at a specific nucleotide sequence. c. extract DNA from cells. d. separate negatively charged DNA molecules. Slide 50 of 32 End Show Copyright Pearson Prentice Hall 13-2 During gel electrophoresis, DNA fragments become separated because a. multiple copies of DNA are made. b. recombinant DNA is formed. c. DNA molecules are negatively charged. d. smaller DNA molecules move faster than larger fragments. Slide 51 of 32 End Show Copyright Pearson Prentice Hall END OF SECTION