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4.21 Prokaryotic Genetics

4.21 Prokaryotic Genetics. By Lance Goodridge and Devin Callanan. Defining Prokaryotes. Unicellular organisms Lacks cell nucleus Lacks mitochondria + chloroplasts. Defining Prokaryotes 2. Very small Live near water Extremophiles. Evolution of Prokaryotes. Organized into two kingdoms

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4.21 Prokaryotic Genetics

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  1. 4.21 Prokaryotic Genetics By Lance Goodridge and Devin Callanan

  2. Defining Prokaryotes • Unicellular organisms • Lacks cell nucleus • Lacks mitochondria + chloroplasts

  3. Defining Prokaryotes 2 • Very small • Live near water • Extremophiles

  4. Evolution of Prokaryotes • Organized into two kingdoms • Very Old • Controversy

  5. Escherichia Coli • The ‘guinea pig’ bacteria • Good for studying

  6. Genomes • Prokaryotes have a genome • DNA = tight loop (shown right)

  7. Plasmids • Also have Plasmids • Additional genes • Can be integrated into bacteria’s DNA (shown right)

  8. OriC • Starts replication process • “Unzips” the DNA • Many AT bases

  9. Helicase • 2 enzymes for DNA replication • Breaks H-bonds • “Supercoils” DNA • Note: The helix of the DNA was omitted for clarity =>

  10. Gyrase • Releases tension • Rejoins strands • Rejoins bonds

  11. DNA Polymerase I • Arthur Kornberg – 1957 • Key to DNA polymerization • Two types

  12. Polymerase and Exonuclease • 5’ to 3’ polymerase • 5’ to 3’ exonuclease • 3’ to 5’ exonuclease

  13. Other DNA Polymerases • Two other polymerases • Pol II • Pol III

  14. Klenow Fragment • 5’ to 3’ exonuclease removed • Labels DNA • Nick translation

  15. 3 Ways Bacteria Acquire New Genes • Mainly reproduce asexually (binary fission shown => NOT an example of gaining new genes) • Three ways to acquire new genes

  16. The F factor (Detailed) • F+: Bacteria w/ F plasmid + pili • F-: Does not have F factor or pili • Hfr: F factor integrated into host's chromosome + pili • F': Hfr w/o F factor + pili

  17. Bacteria Conjugation • F-factor – bacteria grows pili • Forms conjugation tube • If plasmid integrates – Hfr

  18. Transformation • Transfer of exogenous DNA into bacteria • Does not use bacteria or other viruses

  19. Transduction • Infects bacteria with phages • Phage head + assembly shown => • Generalized Trans. • Specialized Trans.

  20. Phage Reproduction • Phages have a lytic cycle => • Breakdown • Relatively quick cycle

  21. Restriction system • Restriction enzymes • Restriction endonuclease • Restriction methylase • Two together = restriction system

  22. Sites Referenced • “Principles of Genetics” Online Textbook • http://www.sciencegateway.org/resources/biologytext/pge/tools.html • http://en.wikipedia.org/wiki/Prokaryote • http://www.biology.ewu.edu/aHerr/Genetics/Bio310/Pages/ch15page/LN13final.pdf

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