1. Do Now  What is replication?  Where does this take place?

2. DNA Replication!

3. Objectives  Explain what replication is and why it must occur in our bodies.  List the different enzymes involved in each step of replication and what they do.  Compare and contrast leading vs. lagging strands.

4.  https://www.youtube.com/watch?v=5qSrmeiWsuc https://www.youtube.com/watch?v=5qSrmeiWsuc

5. Semiconservative Replication  Parental strands of DNA separate  Each strand serve as template  DNA molecules produced have one strand of parental DNA (old) and one daughter strand (new)

6. Enzymes involved  Helicase- Unzips the DNA strand.  Primase- RNA Primer (tells the next enzyme where to begin!)  DNA polymerase- adds nucleotides.  DNA ligase- links together fragments.

7. Steps to DNA Replication 1. Unwinding  DNA helicase (enzyme) unwinds and unzips the DNA – breaking the hydrogen bonds between the strands  Single-stranded binding proteins - go to DNA strand to keep them separated during replication.  RNA primase adds a short segment of RNA, called an RNA primer, on each DNA strand.

8. Steps to DNA replication DNA unwinds at different spots (Origins) At the replication fork, an enzyme (Helicase) breaks the hydrogen bonds between the bases.

9. Steps to DNA Replication 2. Base Pairing  DNA polymerase (enzyme) adds complementary nucleotides to parent DNA strand  Only adds in the 5’ to 3’ direction.

10. 2. Base Pairing (cont.)  Two daughter strands of DNA are made differently  Leading Strand- Elongated as the DNA unwinds.  Built continuously with out breaks  Lagging Strand- Elongates away from replication fork.  Built discontinuously  makes several small fragments of DNA called Okazaki Fragments

11. Leading and Lagging Strands

12. Steps to DNA Replication 3. Joining  DNA Polymerase removes RNA Primer and fills it in place with DNA nucleotides  DNA ligase links the Okazaki Fragments.

13. DNA Replication

14. Mistakes in DNA  DNA replication takes a lot of energy.  During replication, mistakes are made. (mutations)  Enzymes “proof read” and repair the mistakes.

15. Eukaryotes VS. Prokaryotes  Eukaryotic DNA unwinds in multiple areas as DNA is replicated.  In prokaryotes, the circular DNA strand is opened at one origin of replication.

16. Do Now Label the diagram

17. Do Now  Label the DNA Replication Diagram

18.  http://highered.mheducation.com/sites/0072943696/st udent_view0/chapter3/animation__dna_replication__ quiz_1_.html http://highered.mheducation.com/sites/0072943696/st udent_view0/chapter3/animation__dna_replication__ quiz_1_.html