1. DNA replication animation- http://www.johnkyrk.com/index.html
Fig 7.16

2. Fig 7.22

3. Sometimes errors are made.

4. Error
Luckily, errors can be repaired.
As they occur by DNA polymerase

7. How does E. coli know which strand is new?

11. Errors are made during DNA replication
3,000,000,000 (3 billion) base pairs/human cell
with
1 error/1 billion base pairs not repaired
= (average)
~6 errors each time DNA is replicated

12. Not all errors get repaired.
These are mutations.

13. Telomeres are non-gene DNA at the ends of DNA strands.

14. Telomeres are non-gene DNA at the ends of DNA strands.
Telomeres are shortened during DNA replication.

15. The problem of replicating ends
Fig 7.25

16. Telomere lengthening by telomerase
Fig 7.26

17. Elongation of complementary telomere strand
Fig 7.26

18. The telomere forms a protective cap on the end of the DNA with several cap proteins
Fig 7.27

19. Telomeres are non-gene DNA at the ends of DNA strands.
Telomeres are shortened during DNA replication, and also by DNA damage.

20. Telomeres are non-gene DNA at the ends of DNA strands.
Short telomeres will cause cells to stop replicating or cell death.
The critical size is unknown.

21. Human
Life
Cycle
high levels of telomerase
very little telomerase

22. Why not produce telomerase all of the time?
high levels of telomerase
very little telomerase

23. Telomeres are non-gene DNA at the ends of DNA strands.
Telomeres are shortened during DNA replication, and by DNA damage.
Short telomeres will cause cell senescence or cell death.
Telomere size is a measure of mutations.

24. for W 11/7: Do telomere dynamics link lifestyle and lifespan?
Pat Monaghan and Mark F. Haussmann
TRENDS in Ecology and Evolution Vol 21 pg 47