BIOL 102 Lecture Notes - Dna Replication, Okazaki Fragments, Helicase
20 Nov 2012
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Document Summary
Bidirectional replication, single origin of replication in bacteria, multiple origins of replication in eukaryotes. Starts at origin of replication and starts to unwind. Which of the two copies will go to the daughter cell. Enzyme: dna helicase 0 binds to the double strand and opens up the strand. Single stranding binding proteins keep dna from reassembling together. While separating down the line causes to supercoil. Rna primer- added first by dna primase (two added which go along the strands) Subunits add at 3" end but new strands elongate in opposite directions. Elongation proceeds smoothly on leading stand addition to lagging stand is by 100- Okazaki fragments lagging stand grows discontinuously because of the size of these fragments. Dna polymerase iii can add a 3 prime end. Dna polymerase cannot copy the top of the dna stand with a 3" end. If this replication problem were not solved, linear chromosomes would become slowly shorter.
