LS3.1 Week4 Lec11

Conformation dna polymerases cannot synthesize dna

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Unformatted text preview: tarting from dNTPs: they require at least a dinucleotide as a primer. RNA polymerases can initiate synthesis starting from NTPs. It was found that a special RNA polymerase, Primase, synthesizes a short RNA to which DNA is that is complementary added on. The RNA must then be removed so that the duplicated genome is entirely DNA. DNA polymerase can initiate synthesis using either an RNA primer or DNA primer annealed to the DNA template DNA Polymerase 3' 5' RNA Primer 3' DNA 5' DNA template DNA synthesis is only in 5'-3' direction Consequence of anti-parallel DNA strands and direction of DNA synthesis: Two strands are synthesized in the opposite direction. unwinding more in this <- direction each strand as template Replication Fork Replication fork moves continuously toward the duplex region of unreplicated DNA. RNA primer Leading strand 5' 3' 5' 5' 3' 5' Leading strand Origin of replication Since DNA synthesis is always 5' to 3' one daughter strand is synthesized continuously and the other is synthesized discontinuously. lags because of the directionality the leading strand goes continuous t...
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