8. DNA Replication Replication is semi-conservative (one strand is old, one strand new)

10. Origins of Replication Where DNA Replication starts Differs between organisms –Prokaryotes = 1 origin of replication –Eukaryotes = many different origins of replication

12. General Process of DNA Replication Step 1: Initiator Proteins bind to origins of replication to begin replication –Attracts other enzymes involved in replication process Step 2: –DNA Helicase separates the DNA helix

13. General Process Step 3: Primase builds a primer at the 5’ end of the new DNA strand 3’ 5’ Primase RNA Primer DNA Polymerase III

14. General Process Step 4: DNA Polymerase III builds the new strand of DNA in a 5’ to 3’ direction

16. -Nitrogenous bases are located in the cytoplasm -They enter the nucleus through the pores in the nuclear membrane

17. Problem… How can both strands of DNA be replicated in a 5’- 3’ direction at the same time if they are antiparallel? Answer: leading and lagging strands

18. Leading and Lagging Strands Leading strand is synthesized continuously in the direction of replication (goes in the same direction as helicase) Lagging strand is synthesized in short fragments the opposite direction of replication (opposite direction as helicase)

20. DNA Ligase DNA Ligase seals Okazaki fragments together –Forms covalent bonds between nucleotides to create a continuous strand of DNA

24. Thymine is added accidentally. DNA polymerase cuts the damaged DNA. The proper base is added. Ligase joins the two spots.