Question

2) Where is DNA replication initiated on the bacterial chromosome and what happens at
this place?
3) How is it possible that E. coli can have a generation time of 20 mins when it takes the
DNA to replicate in 40 min?
4) If you discovered that a particular bacterium had two DNA molecules in it, one that
was 450 kilobases and one that was 550 kilobases, how would you decide if it had one
chromosome and one plasmid, or two chromosomes?
5) What types of genes are found on plasmids?

Answer 1

6) You are studying a plasmid that confers high level of mercury resistance to E. coli.
The plasmid copy number is roughly 20 per cell. After mixing the E. coli plasmid strain
with an Agrobacterium species (normally sensitive to Hg) and plating on mercury, you
observe Hg resistant colonies of E. coli and Agrobacterium. How would you classify this
plasmid?
7) How does R1 partition into a new cell and what is the mechanism that ensures each
daughter cell gets a plasmid?

Answer 2

1) What does the core part of RNA polymerase do? What about the sigma subunit?
2) Why does sigma 70 recognize different promoters than the heat shock sigma factor does? What is the
purpose of having these different promoters? What does it mean that some promoters are poor matches to consensus? What is the implication of this match for gene expression?
3) Unlike actively growing cultures of Bacillus subtilis old cultures (not growing) have lots of spores. It is
known that special sigma factors are expressed during sporulation. Consider a Bacillus strain that is always expression gfp (SigA promoter) vs. a mutant where that promoter was changed to a SigF promoter. What would the two Bacillus gfp strains look like under a fluorescence microscope during exponential phase of growth? How about in late stationary phase? Note: the green fluorescence protein is very stable.

Answer 3

https://en.wikipedia.org/wiki/Sigma_factor

Answer 4

LOL. Someone removed what I said..........probably because it was true!!!!!!!!!!!!! I can't stop laughing!!!!