(understand replication of telomeres)
I. Semiconservative Replication
A. Has old template strand and new replicated strand
B. Old guy always sided with if any incorrect replication
C. Meselson and Stahl used a heavy Nitrogen isotope in E. coli
1. E. coli is grown for several generations in heavy isotope
2. As generations proceed, heavy molecules slowly fade and density slows
D. Taylor, Woods and Hughes used a heavy hydrogen isotope and colchicine in
root-tip cells
1. Replicated and lights up chromosomes
E. John Cairns demonstrated the gross structure of replicating E. coli
1. Replication is bidirectional
II. Specific origins of replication
A. E coli: oriC site
1. oriC is composed of two elements
2. 13-mer sequence in 3 tandem repeats
a) GATCTNTTNTTTT
3. 9-mer sequence (4 regions)
a) TTATNCANA
4. One side pops open, the other meant for protein binding to help replicate?
5. Necessary and sufficient
B. Yeast
1. Autonomously replicating sequences
2. ATTTATPuTTTA
3. Necessary and sufficient
C. SV40: 64mer core origin (virus)
1. AT-rich region
2. Protein binding site (27mer palindrome)
III. Bidirectional Replication
A. Bacteriophage: schnos and inman
1. Diagram showing the positions of AT:rich denaturation sites in the circular
form of the chromosome
2. Left end of linear form, pointing toward the right end
3. Bidirectional was proven
B. Bacteriophage T7
1. Linear genome
2. Just from sheer logic, bubble opening in the middle shows bidirectional
movement
IV. Players of Replication
A. DNA polymerase I
1. Arthur Kornberg: demonstrated in vitro DNA synthesis (1957) →
purified DNAP I
2. Required :