question archive Consider the following experiment: Radioactive (14C) uridine (lots of it) is added to a growing culture of bacteria for 10 seconds and then an excess of unlabeled uridine, along with the drug rifamycin, is added to the culture [rifamycin blocks the initiation of transcription, but not elongation)
Consider the following experiment: Radioactive (14C) uridine (lots of it) is added to a growing culture of bacteria for 10 seconds and then an excess of unlabeled uridine, along with the drug rifamycin, is added to the culture [rifamycin blocks the initiation of transcription, but not elongation)
Subject:BiologyPrice: Bought3
Consider the following experiment: Radioactive (14C) uridine (lots of it) is added to a growing culture of bacteria for 10 seconds and then an excess of unlabeled uridine, along with the drug rifamycin, is added to the culture [rifamycin blocks the initiation of transcription, but not elongation). At two-minute intervals, 1 ml samples are removed and placed on ice. Once all the time points are collected, the ice-cold bacteria are lysed and DNase is added. After incubation for one hour to ensure complete DNase digestion, TCA [trichloroacetic acid) is added to the sample. This causes all macromolecules larger than a few nucleotides to collect together and precipitate, after which they can be collected on a ?lter. Smaller molecules, such as free nucleotides, will pass through the ?lter. Total radioactivity on each ?lter is then measured. The data obtained are shown in the table below. Time in Acid precipitable minutes radioactivity [cpm) 0 50,240 2 35,050 4 27,510 6 23,725 8 21,850 10 20,920 12 20,460 14 20,230 16 20,110 18 20,010 a. What do you think this experiment was trying to measure? b. Tell me everything you can about the RNA populations in E. coli based on this data. Hint: there are at least two different types of observations you can make.
