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DNA Replication. 1. Process by which DNA makes a copy of itself 2. Occurs during S phase of interphase before cell division 3. Extremely rapid and accurate (only 1 in a billion are incorrectly paired) 4. Requires many enzymes & ATP (energy)
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DNA Replication 1. Process by which DNA makes a copy of itself 2. Occurs during S phase of interphase before cell division 3. Extremely rapid and accurate (only 1 in a billion are incorrectly paired) 4. Requires many enzymes & ATP (energy) 5. Begins at special sites along DNA called origins of replication where 2 strands open & separate making a replication fork
6. Nucleotides added & new strand forms at replication forks 7. DNA helicase (enzyme) uncoils & breaks the weak hydrogen bonds between complementary bases (strands separate) 8. DNA polymerase adds new nucleotides to the exposed bases
9. Leading strand (built toward replication fork) completed in one piece 10.Lagging strand (built moving away from the replication fork) is made in sections called Okazaki fragments
11. DNA ligase helps join Okazaki segments together 12. DNA polymerase proofreads the new DNA checking for errors & repairing them; called excision repair 13. Helicase recoils the two, new identical DNA molecules
Please watch video clip on DNA Replication • https://www.youtube.com/watch?v=5qSrmeiWsuc