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Frontiers of Genetics Ch. 13

Frontiers of Genetics Ch. 13. Ms. Levensailor. Biotechnology: The use of organisms to perform practical tasks for humans. Analyze and manipulate genomes at the molecular level. Called DNA technology. Use E. Coli and bacteria for models of gene manipulation. Why bacteria?

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Frontiers of Genetics Ch. 13

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  1. Frontiers of GeneticsCh. 13 Ms. Levensailor

  2. Biotechnology: The use of organisms to perform practical tasks for humans. • Analyze and manipulate genomes at the molecular level. • Called DNA technology. • Use E. Coli and bacteria for models of gene manipulation. • Why bacteria? • Unique way of creating genetic recombination. Biologists manipulate DNA

  3. Demonstrated that 2 bacteria can form a tunnel like connection. • Pass genes to each other. • Results in new combinations of genes. • 2 other methods: • Viruses can carry bacterial genes from one bacterial cell to another. • Take up loose pieces of DNA from their surroundings. Lederberg &Tatum

  4. Scientists make use of the way bacteria can transfer and recombine DNA. • Combine genes from different sources into a single DNA molecule. • Can be from different species. Recominant DNA Technology

  5. Bacteria contain plasmids: • A small circular DNA molecule. • Separate from the larger bacterial chromosome. • Carry a number of genes. • Can make copies of itself. • Plasmid replication: • One copy can pass from one bacterial cell to another. • Results in gene sharing. Engineering Bacteria

  6. Bacteria can carry plasmids containing genes that make them resistant to antibiotics. • Plasmid copies of this gene are spread to the bacterial population. • Result of this: • Increasing variety of bacteria that are resistant to current antibiotics. Beneficial Results of Gene Sharing

  7. Biologists use plasmids to move pieces of DNA into bacteria. • Example: genes useful for products • Process of Gene Cloning: • 1. Plasmid is removed from bacterial cell. • 2. Desired gene (from any kind of cell) is inserted into the plasmid. • 3. Plasmid is now a combination of original DNA and new DNA (Recombinant DNA). • 4. It is now put back into a bacterial cell, and replication occurs many times. How can humans benefit?

  8. Plasmids: carriers of genetic information. Genetically Engineered Bacterial Cell

  9. How do we remove a gene from one DNA molecule and put it into another? • A piece of DNA containing the desired gene must be “cut”. • RESTRICTION ENZYME • Naturally found in bacteria and protect against intruding DNA from other organisms. • Chop up the foreign DNA into small pieces. • Bacturium’s DNA is protected chemically from being chopped up by its own restriction enzymes. Cutting and Pasting DNA

  10. Recognize specific short nucleotide sequences in DNA molecules. • Cuts at sugar-phosphate bonds in DNA backbone. • Most make staggered cuts. • Leaves single stranded DNA hanging off the ends of the fragments. • “Sticky Ends” are available to bind to any sequence that is complementary to it. Restriction Enzymes

  11. Can be used to recombine DNA. • “Pastes” the sticky ends together. • Repairs DNA backbone. Pasting DNA

  12. We want to insert Protein V-gene. Cloning Recombinant DNA

  13. Cloning recombinant DNA results in many different clones. • Each containing different portions of the source DNA. • Results in many genes being cloned in addition to the target gene. • Genomic Library: • Complete collection of cloned DNA fragments from an organism. Libraries of Cloned Genes

  14. How do we find a specific gene in the genomic library? • 1. We must know at least part of the gene’s nucleotide sequence. • Example: • Protein V contains sequence TAGGCT. • Biologists use nucleotides labeled with radioactive isotopes to build a complementary single strand. • Called a nucleic acid probe. Identifying Specific Genes with Probes

  15. 2. We heat the DNA to separate the 2 strands. • 3. Nucleic acid probe is mixed in with the single strands. Identifying Specific Genes with Probes

  16. 4. Probe tags the correct DNA portion by pairing with the complementary sequence in the Protein-V gene. • 5. Biologists use a radioactive marker to identify the bacterial cells with the desired gene. Identifying Specific Genes with Probes

  17. Plasmid isolated 1 DNA isolated 2 Gene inserted into plasmid 3 Plasmid put into bacterial cell 4 Cell multiplies with gene of interest 5 Bacterium Cell containing gene of interest Plasmid Bacterial chromosome Recombinant DNA (plasmid) DNA Gene of interest Recombinant bacterium Copies of gene Copies of protein Clone of cells Gene for pest resistance inserted into plants Protein used tomake snow format highertemperature Gene used to alter bacteria for cleaning up toxic waste Protein used to dissolve bloodclots in heart attack therapy Uses of Bacterial Plasmids to clone genes

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