Problem Set: Lecture 36 RNA synthesis

1). Predict the results when the core RNA polymerase is mixed with double-stranded bacterial DNA in the presence of nucleoside triphosphates under optimal conditions for transcription activity. No transcription will occur without sigma factor.

2). Describe the role of the following: See lecture notes

a). Sigma factor

b). Rho protein

c). Hairpin loops in transcriptional termination in Eukaryotes- Not used. Euk. RNA polymerase does not undergo directed termination.

3). The bacterial genome contains hundreds of promoters for mRNA synthesis, but fewer than 10 promoters for rRNA synthesis. Despite these large differences in promoter number, the synthetic capacities for rRNA and mRNA are not very different. What does this observation suggest about the properties of promoters for protein-encoding genes? That these promoters deviate from the consensus sequence.

Please included the consensus sequence for bacterial promoters in your answer. See notes.

4). RNA polymerase does not have proofreading activity. Why is this not Detrimental to the cell? If errors occur during synthesis, the RNA molecule can be degraded and a new polymer synthesized. This being said, the cell still requires high fidelity synthesis of RNA because of the large energy cost associated with RNA production.

5). Describe the differences between bacterial and eukaryotic RNA polymerases. See notes-also think of the similarities.