DNA replication

DNA replication - fragments. Why do you need protein to...

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In both eukaryotic and prokaryotic cells, cell replication occurs bidrectionally. This was determined experimentally by cutting E.Coli near origin of replication and observing growth; bubble (indicating replication) grows both ways while center stayed constant. DNA synthesis occurs 5’ -> 3’: PROBLEM: How does cell keep the two opposite strands of ssDNA at one replication fork to replicate at the same direction? SOLUTION: Existence of leading and lagging strands: 1. Leading strands are synthesized continuously. 2. Lagging strand: strand that is discontinuously synthesized in Okazaki
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Unformatted text preview: fragments. Why do you need protein to bind ssDNA? To prevent hybridization of complementary strand. Primers (primases) are short RNA fragments to start syntheses. Acts FIRST; makes RNA based on DNA template. DNA polymerase needs this to start replication. DNA pol alpha: In eukaryotes, synthesizes short DNA from the RNA primer, resulting in RNA-DNA hybrid. Why RNA primer used to synthesize? Hypothesis is that evolution may have conserved RNA functionality in synthesis before usage of DNA. Why Large T-antigen (helicase; unwinds dsDNA):...
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