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Transcript
Manipulating DNA Slide 1 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology Scientists use knowledge of the structure and function of DNA to manipulate it. Slide 2 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology Techniques: • extract DNA from cells • cut it into smaller pieces • identify the sequence of bases in it • make unlimited copies of it Slide 3 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology DNA Extraction The cells are broken open and the DNA is separated from the other molecules. Slide 4 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology Cutting DNA DNA is cut into smaller fragments using restriction enzymes. Slide 5 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 6 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology Separating DNA - gel electrophoresis DNA fragments are placed at one end of a porous gel and an electric voltage is applied. The negatively-charged DNA molecules move toward the positive end of the gel. Slide 7 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 8 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 9 of 32 End Show 13-2 Manipulating DNA The Tools of Molecular Biology Power source An electric voltage is applied to the gel. DNA fragments move across the gel. Smaller fragments move faster and farther. Gel Electrophoresis Slide 10 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA The Tools of Molecular Biology DNA fragments make a pattern of bands. These bands can then be compared with other samples of DNA. Longer fragments Shorter fragments Gel Electrophoresis Slide 11 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Using the DNA Sequence Cutting and Pasting Enzymes that splice DNA together make it possible to take a gene from one organism and attach it to the DNA of another. Such DNA molecules are called Recombinant DNA. Slide 12 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Using the DNA Sequence Making Copies Polymerase chain reaction (PCR) allows biologists to make copies of genes. -DNA is heated to separate its two strands. -Primers bind to the single-stranded DNA. -DNA polymerase makes copies of the DNA Slide 13 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 14 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Cell Transformation Recombinant DNA Host Cell DNA Target gene Modified Host Cell DNA Slide 15 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Transforming Bacteria Transforming Bacteria A cell takes in DNA from outside the cell. Foreign DNA is first joined to a small, circular DNA molecule in bacteria known as a plasmid. Slide 16 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Transforming Bacteria Recombinant DNA Gene for human growth hormone Gene for human growth hormone Human Cell Bacterial chromosome DNA Sticky ends recombination DNA insertion Bacteria cell Plasmid Bacteria cell containing gene for human growth hormone Copyright Pearson Prentice Hall Slide 17 of 32 End Show 13-2 Manipulating DNA Transforming Plant Cells Transforming Plant Cells • A bacterium exists that produces tumors in plants. • Researchers can inactivate the tumor gene and insert a piece of foreign DNA into the plasmid. • The recombinant plasmid can then be used to infect plant cells. Slide 18 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Gene to be transferred Transforming Plant Cells Agrobacterium tumefaciens Inside plant cell, Agrobacterium inserts part of its DNA into host cell chromosome. Cellular DNA Recombinant plasmid Plant cell colonies Transformed bacteria introduce plasmids into plant Copyright cells. Pearson Prentice Hall Complete plant generated from transformed cell. Slide 19 of 32 End Show 13-2 Manipulating DNA Transforming Animal Cells Transforming Animal Cells • DNA can be directly injected into the nucleus of an egg cell. • Enzymes insert the foreign DNA into the chromosomes of the injected cell. Slide 20 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Transforming Animal Cells Recombinant DNA Recombinant DNA Flanking sequences match host replaces target gene Target gene Modified Host Cell DNA Slide 21 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Applications of Biotechnology Transgenic Organisms • Contains genes from other species. Slide 22 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Transgenic Organisms Transgenic Microorganisms • Transgenic bacteria produce important substances useful for health and industry. • insulin • growth hormone • clotting factor Slide 23 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Transgenic Organisms Transgenic Animals • Transgenic animals have been used to improve the food supply. • Mice have been produced with human genes that make their immune systems act similarly to ours. • This allows scientists to study the effects of diseases on the human immune system. Slide 24 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Transgenic Organisms Transgenic Plants • Transgenic plants are now an important part of our food supply. • Many of these plants contain a gene that produces a natural insecticide, so plants don’t have to be sprayed with pesticides. Slide 25 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA 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 26 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Cloning Cloning Dolly Donor Nucleus Fused cell Egg Cell Embryo Cloned Lamb Foster Mother Copyright Pearson Prentice Hall Slide 27 of 32 End Show 13-2 Manipulating DNA Cloning Cloning Dolly Slide 28 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Cloning Cloning Dolly Slide 29 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Cloning Cloning Dolly Slide 30 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Cloning Cloning Dolly Slide 31 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Cloning Cloning Dolly Slide 32 of 32 Copyright Pearson Prentice Hall End Show 13-2 Manipulating DNA Cloning Cloning Dolly Slide 33 of 32 Copyright Pearson Prentice Hall End Show