key words: DNA, replication, polymerase, template

1. review DNA structure
1. sugar - phosphate backbone
2. nucleotides
2. because of nucleotide pairing, each strand contains all information for making a new molecule
1. three alternative models for DNA synthesis
1. semi-conservative: strands intact, serve as templates
2. conservative: duplex intact, serves as template
3. dispersive: strands break up
2. using radioactive labels to test these predictions
3. DNA polymerases
1. polymerases are enzymes that synthesize large molecules from component parts
2. different DNA polymerases with different functions
4. DNA synthesized only in one direction
1. strands run in opposite directions so synthesis proceeds in opposite directions
5. Bio 1B students should become familiar with the polymerase chain reaction (pg240)

1. In figure 12.2 b (text page 234), explicit predictions are made for two of the alternative models, semi-conservative and conservative.  What are the predictions for the dispersive model for each generation of DNA synthesis?

2.  What variables would you expect to be controlled for during the experiment discussed above? (hint:  you need to control for any variable that could cause differences among the treatments apart from the mechanism of replication)

3.  Why is one strand of the DNA duplex referred to as the "lagging strand"?

4.  The primers used in PCR are DNA primers, whereas the lagging strand primers are RNA primers.  Is there a functional significance to this difference?

Answers