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Chapters 15 & 16

Chapters 15 & 16. Control & Manipulation of Genes. Gene controls. Before Transcription Access Acetylation loosens grip of histone, allowing access of polymerase to DNA Methylation of an allele blocks that gene’s affect How transcribed

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Chapters 15 & 16

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  1. Chapters 15 & 16 Control & Manipulation of Genes

  2. Gene controls • Before Transcription • Access • Acetylation loosens grip of histone, allowing access of polymerase to DNA • Methylation of an allele blocks that gene’s affect • How transcribed • Gene sequences rearranged or multiplied, generate large amounts of gene product

  3. Gene controls • Transcription Processing • mRNA cannot pass out of nucleus without transport protein • Some proteins can block translation from starting • Translation Control • Affect ribosome components (no rRNA, no translation) • Control speed of breaking down mRNA (how many times it can be reused)

  4. Gene controls • X Chromosome Inactivation • Females XX • One X chromosome is 75% “shut down” • Barr body—condensed X chromosome • Random

  5. GENE CONTROLS—PROKARYOTES • Operon—arrangement of promoter and operators that control access to a gene • Lacoperonin E. coli cells • E. coli normally doesn’t use lactose (milk sugar) • Lacoperon binds to gene that would allow use of lactose, prevents it’s transcription • When glucose is scarce but lactose present, activator is synthesized • Activator then prevents lacoperon from functioning, allowing lactose to be used • Inhibition can be reversed

  6. Manipulating dna • Recombinant DNA—any DNA molecule consisting of base sequences from two or more organisms of the same or different species. • Able to combine genetic sequence of different species • Restriction enzymes • Plasmids & cloning vectors

  7. Restriction enzymes • A restriction enzyme is added to a solution with DNA • Enzyme “cuts” DNA at a specific place • Can fuse with DNA molecule “cut” with same enzyme

  8. Restriction Enzymes

  9. Plasmids • Bacteria have two forms of DNA • One chromosome, a single circular DNA strand • Plasmids—small circles of “extra” DNA with only a few genes • Bacteria divide rapidly, providing many new organisms in a short period of time.

  10. plasmids • In nature, bacteria can share characteristics through plasmids • Antibiotic resistance

  11. plasmids • With restriction enzymes, can splice DNA into plasmid • Plasmid taken into bacteria cells

  12. plasmids • “Donor” gene is used by bacteria, produces product of gene • Is now part of bacteria’s genetic code, is passed on during division

  13. plasmids • Uses • Laboratory studies of specific genes • Produce products quickly & cheaply • Insluin • Antibiotics • Vaccines • Animal diseases • HIV • Ebola

  14. pcr • Polymerase Chain Reaction (PCR)—method to reproduce fragments of DNA millions or billions of time • Primer—short stretch of synthetic, single-stranded DNA

  15. pcr • Primers are added to solution with DNA fragments and polymerase • Solution is heated, denaturing and “opening” DNA • Solution is cooled • Primers attach to matching base pairs during cooling • Polymerase starts at primer, synthesizes DNA chain • Process is repeated

  16. PCR • Each “cycle” results in exponential growth • Quickly grow a segment of DNA

  17. pcr • Uses • Forensics • Diagnostics (viral & bacterial diseases) • Paternity or relationship testing • Historical analysis • Mummies, mammoths, etc.

  18. Gel Electrophoresis • DNA is mixed with certain compounds in a solution • The solution is placed into a gelatinous substance • Electrical charge is carried along the gel • The DNA separates along the gel in a pattern based on the structure and weight of the individual genes

  19. Dna fingerprinting • Everyone’s DNA is unique to them • Base-pair patterns different between people • PCR & electrophoresis to find & analyze DNA • 1 in 3,000,000,000,000 chance of unrelated people having identical DNA

  20. Human genome project • 1988—National Institutes of Health combined previously begun research into one project • 2003—Human genome officially completed • Almost 20,000 confirmed genes • Over 2,000 possible genes • Don’t know what all of these genes do! • Much of human genome DOESN’T code for proteins • Many might regulate expression of other genes…. “Master Control” genes

  21. Human genome project • Study diseases & disorders • Be able to predict and detect disease • Gene therapy—transfer one or more normal or modified genes into a person’s body cells • Correct genetic defect • Boost resistance to disease • Imperfect at this time

  22. Genetic engineering • Bacteria • Insulin • Blood-clotting factors • Hemoglobin • Vaccines • Environmental clean-up • Oil spills • Pollutants • Radioactive waste

  23. Genetic engineering • Plants • Drought resistance • Disease resistance • Herbicide resistance • Soil tolerance • Greater yield • Better nutrition

  24. Genetic engineering • Animals • Medical research • Mice susceptible to human diseases • Disease resistance • Environmental resistance • Featherless chickens • Medical proteins • Cattle—human collagen (cartilage, bone, skin repair) • Better nutrition • Low-fat pigs

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