methylation sites 5gametc3 are more common near the

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Unformatted text preview: ng DnaB helicase, etc. Need to prevent re ­initiation DamI methylase methylates both strands eventually, but before it does, the newly replicated product is hemi ­methylated, which prevents DnaA recognition.  ­ ­> methylation sites (5’ ­GA(me)TC ­3’) are more common near the OriC, they also become hemi ­methylated earlier and remain hemi ­methylated longer than distal sites, because OriC sequence is the most important in directing initiation Remember that cell cycle is high regulated, but tumor cells can bypass checkpoints to reinitiate DNA replication, often with terrible consequences such as over ­ expression of oncogenes The End: Bacteria: simple circular plasmid, 2 forks initiate and eventually meet to complete replication Eukaryotes: linear ­ ­> “end of replication problem” Because every time you copy the lagging strand, after the last RNA primer is degraded at the far 3’ end of the parental strand, your Polymerase can’t fill in the gap, because it can never go 3’ ­>5’; you’ll lose a bit of DNA each time. Therefore, we have telomeres at the end of DNA, acti...
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This document was uploaded on 09/12/2011.

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