Biochem 501: Part IV.5: Large Scale Genomics

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  1. Recombination can occur:
    • In response to DNA damage
    • Spontaneously during meiosis
    • When mediated by enzymes (recombinase, integrase)
    •      -Tyrosine and Serine recombinases
  2. Examples of enzymes mediated site-specific recombination and integration
    • Targeted elimination of a gene in a specific tissue
    • Integrate genetic material at specific location in genome (plasmids)
  3. Two possible outcomes of site-directed recombination
    • DNA inverted or DNA excised
    • Enzymes recognize sequences that direct recombination
  4. Sequential phosphoryl-transfer reactions mediated by:
    • Tyrosine recombinases
    • Take 1-2+A-B to A-2+B-1
  5. Steps of Tyrosine recombinase mediated phosphoryl-transfer
    • Tyrosine OH attacks P, breaks one side of each helix.
    • Strands reconnect with opposite helix
    • Attacks strands on other strand of the two helixs
    • They recombine same way
  6. Serine recombinase generates what?
    • DS breaks to exchange DNA
    • Process is same as Tyrosine except both at same time
  7. Difference between serine and tyrosine recombinases
    • Tyrosine= On side broken/recombined at a time
    • Serine= Both strands broken at same time, recombined at same time
  8. Mendelian genetics dictate that:
    Genes are transmitted, intact
  9. What does not follow mendelian genetics and who found it
    Maize pigmentation and Barbara McClintock
  10. Transposons are
    • Mobile DNA elements that jump around a genome
    • Cause mutations, effect gene expression
  11. How does a transposon jump around a genome
    • Transposition:
    • 1. Transposase binds to short DNA sequence
    • 2. Transposase oligomerizes on DNA to form "synaptic" complex (attach DNA at either end of transposon to each other and 'pinch' transposon off)
    • 3. transposase cleaves adjacent DNA via phosphoryl transfer reactions excising transposase+transposon DNA
    • 4. transposase-DNA complex binds to target DNA (binds in staggered cut, results in identical chunks on either side, Marker for transposon)
    • 5. 3'OH groups of transposon DNA attack the target DNA, integrating the transposon DNA
    • 5. DNA polymerase and ligase seal gaps
    • Image Upload 1
  12. Transposons do what:
    Generate phentypic variation, diversify genomes and contribute to evolution
Card Set
Biochem 501: Part IV.5: Large Scale Genomics
Biochem 501 FINAL
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