1. CH 11: DNA Replication Complementarity ”It has not escaped our notice that the specific pairing we have postulated immediately suggests a possible copying mechanism … “ Mode of DNA Replication Conservative Semiconservative Dispersive

2. Origins and Directions Terms: Replication fork Replicon In E.coli : replication initiated in only one region - oriC replication is bidirectional termination region - ter

3. DNA Polymerases chain elongation in a 5’-to-3’ direction biological activity?

4. Initiation *Primase *Strands must separate Helicases SSBPs DNA gyrase *Two strands of a double helix are antiparallel Continuous DNA synthesis = leading Discontinuous DNA synthesis = lagging

5. DNA Synthesis Synthesis on leading and lagging strands A coherent model:

6. DNA Synthesis Eukaryotes DNA unwinds at a replication origin Two replication forks form Bidirectional synthesis of DNA Much more DNA; complexed with proteins Eukaryotes have much more DNA Yeast 250-400 replicons Mammalian cells up to 25,000 Solution: Multiple replication origins Yeast 4X that of E. coli Drosophila 100X that of E. coli