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Announcements

Announcements. Ms. Laina Long from the UCLA Bridges Program will give a brief presentation today at 10:40 in this room. She will give you an overview of this paid summer research internship program at UCLA and can answer any questions you may have.

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Announcements

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  1. Announcements • Ms. Laina Long from the UCLA Bridges Program will give a brief presentation today at 10:40 in this room. She will give you an overview of this paid summer research internship program at UCLA and can answer any questions you may have. • Essay exam on Friday. I do want to state that while the genetics portion is focused a problem solving format there could be a definition, result to interpret or genetic concept to briefly explain. The emphasis is on the genetic problems. • The next problem will be due on THURSDAY March 13th instead of Tuesday March 11th.

  2. Ch. 8 Viral Genetic Systemspart 2

  3. Various viral shapes Influenzya A Ebola Herpes HIV

  4. Viruses: highly varied • RNA containing or DNA containing • Single stranded or Double stranded • Linear or circular

  5. Bacteriophages & Transduction • Transduction: gene transfer from virus to bacterium • Virulent phages lytic • Temperate phages lysogenic

  6. Virulent Bacteriophages & Lysis

  7. Viral Plaques “clear spaces” This “cloudy:area is living bacteria

  8. But: Temperate Phages are Lysogenic Bacteriophages

  9. Transduction: Using Phages to map bacterial genes E. coli

  10. Generalize Transduction • Requires lytic bacteriophages • Bacterial chromosome degraded • Phage can transfer & recombination bacterial gene to different bacterium • Rare event

  11. Evidence to support transduction

  12. Evidence to support transduction

  13. Mechanism for: Generalized Transduction

  14. Mechanism of Generalized Transduction(one more time)

  15. Evidence to support & calculate frequency of recombination following transduction

  16. EXPERIMENT SUPPORTING PHAGE RECOMBINATION h-r+ X h+r- Progeny Phage produced

  17. Count colonies by phenotypes: corresponds to genotypes • Determine parental phenotye • Determine recombinant phenotype

  18. Specialized Transduction Location, location, location! “Targeted transfer of genes: genes must be located at specific site on bacterial genome!

  19. Specialized Transduction • Gene transfer from phage to bacterium • Site specific transfer • Requires lysogenic bacteriophages • Lambda phage one of the best studied

  20. a. Movement of the prophage

  21. b. Another possible movement of prophage

  22. Now what could happen. Leads to stable transductant Leads to unstable transductant

  23. Unstable Transductant

  24. Fine Structure Analysis of Bacteriophage genes • Early studies on the structure of a “gene” go beyond recombination experiments • Mutations were studied in phage • Are mutations within the same gene or affecting different genes? • Transduction is used to answer these questions. • Let’s now look how these studies taught us some key facts about genes.

  25. Okay, this sounds familiar

  26. Yes, recombination could be observed with these mutants.

  27. Let’s take this one step further • Complementation experiments using transduction • The question is: where do these mutations exist? • Within the same gene or on different genes?

  28. Genes may overlap in the viral and prokaryotic genomes!

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