Chapter 13
DNA Replication and Recombination
Study Outline
1. Structural overview of DNA replication
a. Existing DNA strands act as templates for the synthesis of new strands
b. Three different models were proposed that described the net result of DNA replication
2. Bacterial DNA replication: the formation of two replication forks at the origin of replication.
a. Bacterial chromosomes contain a single origin of replication
b. Replication is initiated at the origin of replication
3. Bacterial DNA replication: synthesis of new DNA strands
a. DNA replication occurs at the replication fork
b. The synthesis of the leading and lagging strands is distinctly different
c. Certain enzymes of DNA replication bind to each other to form a complex
d. Replication is terminated when the replication forks meet at the termination sequences
4. Bacterial DNA replication: chemistry and accuracy
a. DNA polymerase III is a processive enzyme that uses deoxyribonucleoside triphosphates
b. DNA replication is very accurate
5. Eukaryotic DNA replication
a. Initiation occurs at multiple origins of replication on linear eukaryotic chromosomes
b. Eukaryotes contain several different DNA polymerases
c. Flap endonuclease removes RNA primers during eukaryotic DNA replication
d. The ends of eukaryotic chromosomes are replicated by telomerase
6. Homologous recombination
a. The Holliday model describes a molecular mechanism for the recombination process
b. More recent models have refined the molecular steps of homologous recombination
c. Various proteins are necessary to facilitate homologous recombination
d. Gene conversion may result from DNA mismatch repair or DNA gap repair