1. Ms. Edmondson

2.  DNA has to be copied before a cell can divide.  DNA is copied in the S phase synthesis of interphase  New cells will need identical DNA strands

3.  Why?  When cells replicate, each new cell needs it’s own copy of DNA to preserve the hereditary material.  Where?  Nucleus in Eukaryotes.  Cytosol in Prokaryotes  When?  S phase of cell cycle  What?  Many proteins: major is Helicase and DNA Polymerase  How?

5. 1.DNA Helicase 1.DNA Helicase unwinds the DNA strand. replication fork 2.Other enzymes hold the strands apart creating a, replication fork open. 3.DNA Polymerase 3.DNA Polymerase moves along the separated strands and adds bases to the exposed strands using the base pairing rule. 4.The sugar phosphate backbone reforms and two identical strands of DNA are formed.

6.  Bonds between the bases are broken and the strand unwinds.

7.  The DNA strands separate to form a replication fork.

8.  DNA polymerase adds the bases to the to the exposed strands using the base pairing rule.

9.  Two identical strands are formed.

10.  Semi-conservative Replication-  Semi-conservative Replication- This means that each strand is composed of one old strand and one new strand.

11.  DNA Replication in Action! DNA Replication in Action! DNA Replication in Action!