1) The initiation of chromosome replication is a highly regulated process in bacteria. Describe what happens at the origin of chromosomal replication (oriC) to generate two divergent replication forks and to ensure that only one round of replication is initiated at a time. Include a brief description of the way bacteria manage to divide with a generation time shorter than the time it takes to replicate the chromosome (40 minutes at 37oC for E. coli.)
2) Describe the events that take place to ensure that both the leading and lagging strand DNA synthesis occur with high accuracy (~1 mistake per million base pairs) and at the same rate by a single replication fork moving in one direction along the parental chromosome.
3) Two important events in regulating the transcription of a gene or operon are initiation and termination by the RNA polymerase. What are the mechanisms that control these two processes in bacteria? Also, explain transcriptional polarity caused by nonsense and missense mutations in upstream (5') genes in a polycistronic (multiple open-reading frame) mRNA.
4) Translation is less accurate than either replication or transcription, with mistakes occurring in 1/103 to 1/104 amino acids that are incorporated into the growing polypeptide chains. At what steps in the process can the accuracy of translation be compromised and what mechanisms work to increase the fidelity of translation? Why can a higher rate of mistakes be tolerated in translation than in DNA replication or mRNA transcription?
5) a) Describe the definitive experiments that showed that mutations occur randomly in bacteria rather than being induced by selective conditions. b) Explain how one might go about selecting mutations that lead to an auxotrophy (inability to synthesize and essential compound) or a defect in a gene that encodes a protein that is essential for growth under all conditions.