BIOLOGY – CELL DIVISION - -Replisome – 1...

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BIOLOGY – CELL DIVISION S-PHASE - DNA – right turned double helix of two antiparallel covalently bonded glucose/phosphate backbones (held together by Hydrogen bonding AT/GC) - 5’ carbon has a phosphate group - 3’ carbon has a hydroxyl group - Strands are antiparallel - DNA polymerases can add bases to 3’ hydroxyl groups with properly paired bases. - Unwound 3’ end is leading/continuous side - Unwound 5’ end is the lagging/discontinuous strand (okazaki fragments) - Semiconservative – half of the new strand is new, half old. - Helicase unwinds helix (breaking Hydrogen bonds) - Primase adds RNA primers, which act as starting points for DNA polymerase. - DNA polymerase 3 is responsible for adding new base pairs - DNA polymerase 1 is responsible for removing RNA primers
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Unformatted text preview: -Replisome – 1 organelle that holds all DNA replication materials (proteins, enzymes etc.)-Bidirectional replication forks allow for faster replication.-Most prokaryotes have a single bidirectional replication fork (circular chromosome). Their origin does not have to wait until replication is complete before they begin to replicate again-At the end of the 3’ strand there is a gap left where RNA primer has been removed but there is nothing for the polymerase to connect to.-Telomerase (enzyme) adds DNA onto the 3’ end from its own RNA template. Telomeres are repeated over and over again and primer is added to the new end, preventing the loss of DNA-Telomerase is active in germ cells and rapidly cycling cells (cancer cells)...
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