Slide7 - 1/27/10 Direct reversal of pyrimidine dimer...

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Unformatted text preview: 1/27/10 Direct reversal of pyrimidine dimer DNA glycosylases access damaged bases by ‘flipping’ them out of the double helix Figure 9 ­11 http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi? book=mboc4&part=A747&rendertype=figure&id=A837 Non ­homologous end ­joining Non ­homologous end ­joining Ku Ku Nucleases Nucleases Polymerase Ligase Downs et al (2004) NATURE REVIEWS | MOLECULAR CELL BIOLOGY 5:367 Downs et al (2004) NATURE REVIEWS | MOLECULAR CELL BIOLOGY 5:367 1 1/27/10 Double ­strand breaks can be repaired by homologous recombinaCon Homologous recombinaCon can be used as a tool to replace gene sequences in yeast Yellow region would contain a selectable marker sister chromatids or homologous chromosomes http://en.wikipedia.org/wiki/File:HR_schematic_diagram.svg Figure 22 ­11 Select for yeast that have incorporated your selectable marker into their genome DNA dynamics during meiosis (note that only one type of chromosome is shown) 4n 2n 2n Double strand break repair model for homologous recombination 4n 2nd strand invasion and DNA repair synthesis 1n 1n 1n 1n 1n Fig. 10-15 1st strand invasion double Holliday junction Fig. 10-4 2 1/27/10 The orientation of the Holliday junction resolvase determines whether there is an exchange of chromosome arms 2 nicks this orientation 2 nicks this orientation Now we pull the two products apart… Yields these 2 products (no chromosome arm exchange) And we see that there has been an exchange of chromosome arms Resolution of this Holliday Junction did not result in crossing over (See also Fig. 10-3, or see links to animations on web site) Resolution of this Holliday Junction did result in crossing over (See also Fig. 10-3, or see links to animations on web site) RecA/Rad51 carries out homology search, then causes strand exchange From phenotype to underlying geneCc alteraCon – how is this done? wild type Fig. 10-11 apetela2 ap2 mutant no petals develop therefore AP2 function normal petal development 3 1/27/10 Location of genes on maize chromosome 9 unlinked linked Molecular markers across all five Arabidopsis chromosomes http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/L/Linkage.html 4 ...
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This note was uploaded on 03/02/2010 for the course MCB 161 taught by Professor Stacey during the Winter '10 term at UC Davis.

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