1. pp 295 - 301

2. 2. Replication Elongation DNA polymerase – enzyme which does what? In what direction? What is the main version responsible for replication? in prokaryotes: DNA polymerase I, II, III, IV & V in eukaryotes: over 15 different types Nucleotide chains only form in the 5’  3’ direction.

3. DNA Polymerase III Substrates 1. DNA template 2. deoxyribonucleoside triphosphates (dNTPs) 3. RNA primer 5’3’ 5’3’ 5’3’

4. 2. Replication Elongation 1. Primase: 5’3’ 5’3’

5. A 2. Replication Elongation Three steps involved in the addition of every nucleotide to the new piece of DNA are: A T TTP PP

6. 2. Replication Elongation

7. In what direction must the DNA polymerase produce the new strand of DNA? Which direction does the replication fork open?

8. 2. Replication Elongation Prokaryotic DNA is circular. Two DNA polymerases replicated in opposing directions until both strands are completed.

9. 2. Replication Elongation Eukaryotic DNA is linear. DNA polymerases in travel both directions from the ori site. What direction is DNA synthesized?

10. Leading Strand 5’ 3’ helicase SSBPs gyrase primase 5’ 3’ DNA polymerase III

11. Lagging Strand Okazaki fragment 5’ 3’ 5’ 3’ 5’ 3’ helicasegyrase

12. 2. Replication Elongation Okazaki fragments: DNA polymerase I – DNA ligase –

13. 2. Replication Elongation DNA replication occurs: 1. continuously on the _______ strand 2. discontinuously on the _______ strand Replication Animation

14. 3. Replication Termination Telomeres TTAGGG

15. Telomeres

16. Telomerase Explain what happens to the telomere during each round of replication, why this is important and why some cells have a mechanism to repair this while others do not…

17. Telomerase Telomeres and aging?

18. Telomerase Telomerase:

20. Mistakes in DNA Replication Fewer than 1 error in 10 7 NTs Exonuclease – Roles of DNA polymerase I and II

21. Classwork Introduce yourself to your neighbor Everyone get into groups of 2-3 In groups, summarize DNA replication as a series of steps