18 leading lagging why do bacteria do this 19 20 how

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Unformatted text preview: s. 18 Leading Lagging Why do bacteria do this? 19 20 How does it end? Multicellular eukaryotes face another problem: They usually have a LOT more DNA than bacteria. Mycoplasma: 500,000 bp Salmonella: 5,000,000 bp Brewer’s yeast: 12,000,000 bp Malaria parasite: 20,000,000 bp Drosophila (fruit y): 200,000,000 bp Sea urchin: 800,000,000 bp Human: 3,000,000,000 bp Amphibian: up to 100,000,000,000 bp ...And eukaryotic DNA polymerization is generally slower than in bacteria! Solution: use many origins of replication. 21 22 (Where) !"#$#%& !"#$#%& !"#$#%& Potential origins of replication in brewer’s yeast, Saccharomyces cerevisiae John J. Wyrick, et al. Genome-Wide Distribution of ORC and MCM Proteins in S. cerevisiae : High-Resolution Mapping of Replication Origins 23 Matreiya Dunham, UW Genome Sciences Science 294, 2357 (2001) DOI: 10.1126/science.1066101 24 The eukaryotic cell cycle The eukaryotic cell cycle DNA damage checkpoints: * at G1/S * during S phase * at G2/M { I = Interphase M = Mitosis G1 = Gap 1 S = Synthesis G2 = Gap 2 I = Interphase * * M = Mitosis { G1 = Gap 1 S = Synthesis G2 = Gap 2 * The rst key genes known to control the eukaryotic cell cycle were discovered here @ UW by Lee Hartwell (Nobel Prize 2001) 25 review (When) Each eukaryotic origin is licensed to initiate replication once and only once per cell cycle ORC (Origin Recognition Complex) binds to origins, marking each initiation...
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