1. Chapter 12 Topics Models of Replication
Prokaryotic and Eukaryotic Replication
Models of Recombination: read pp

2. Three Models of DNA Replication
Which is correct?

3. DATA TO SUPPORT SEMI-CONSERVATIVE MODEL

4. Prokaryotic Replication
E.coli 4.7 million bp
Bacteria can double every 20 minutes at a rate of 1000 nucleotides/second!

5. 2 models of Prokaryotic Replication
The Theta Model
Rolling Pin Model θ

6. Theta Replication
Radioactive labeled prokaryotic DNA

7. Rolling Pin Model
Occurs in viruses and factor F

8. Prokaryotic Mechanism of Replication
An: overview of E. coli replication

9. Animation of Elongation
Animation of Elongation
Nucleotide polymerization

10. Bacterial Mechanism of Replication
oriC
Key concepts & Proteins
Step 1. Initiation
Step 2. Unwinding: Helicase
helicases

11. Notice: Directionality
Notice: Replication Bubble Forms
Helper proteins
Helper proteins

12. Step 3: Primase
Step 4. Elongation
Okazaki Fragments

13. Prokaryotes Polymerases
The major players are:
Pol l
Pol II
Pol III
Pol IV
Pol V
Removes/replaces primers
repair
ELONGATION: step 4
repair

15. Step 5. Ligation
These darn Okazaki
Fragments!
Ligase

16. Step 6. Termination A certain DNA sequence may replication
A protein may physically replication

17. SUMMARY
Prokaryotic DNA replication
Leading strand
Lagging strand

18. How are mistakes avoided?
By: Nucleotide selection
By: Proofreading
By: Mismatch Repair

19. Fidelity of DNA replication
Only 1 mistake per billion nucleotides!

20. Eukaryotic Replication
A human chromosome about 100 million bp
Replication occurs in minutes to hours!

21. Answer: Numerous replication origins.
Can you notice a difference between this replication process vs bacterial replication?
Answer: Numerous replication origins.

22. Got it!

23. 5’ to 3’ replication occurs in eukaryotes just like in our bacterial friends.

25. Prokaryotic and Eukaryotic Replication are similar but there are some differences; these include…

26. Origins “get tagged” by
a replication licensing factor.

27. There are more and different DNA polymerases.

28. Eukaryotic DNA Polymerases
Priming & replication (RNA polymerase
Replication
Repair & recombination
Repair and replication
Mitochondrial DNA replication
DNA Pol α
DNA pol δ
DNA pol β
DNA pol ε
DNA pol γ

29. Nucleosome Assembly
Unique to eukaryotic replication process

30. What happens when you reach the end of linear DNA?

31. Oops a problem at the end!!

32. Are loss of telomeres related to aging?
Telomeres and Telomerase!
Are loss of telomeres related to aging?

33. Or is too much telomerase activity related cancer?

34. Cells with telomerase activity
Embryonic cells
Intestinal cells
And bone marrow

35. Disease of Aging: Werner’s Disease
Related to mutated helicase; Why would this cause an error in DNA replication?

36. Assignment please read: pp 339-342
The Holliday Model of DNA recombination