The antibiotic rifampicin blocks transcription in many bacteria. In the presence of the antibiotic, adding sigma factor has no stimulating effect on RNA synthesis. A footprinting experiment on a rifamycin treated sample shows that the polymerase remains located at the promoter site in the presence of eNTPs and Mg2 ion. What step of transcription is rifamycin likely to block

What is the name for a substance formed in a chemical reaction

Most animal cells membranes have proteins that pump ions out of the cell and potassium ions into the cell

The kidney filters potentially toxic substances in the blood, and thus “clears” the blood of those substances. this clearance function is dependent upon and proportional to the diffusion gradient of the substance across filtering capillaries, i.e. if the concentration of the substance is doubled, twice as much will be cleared from each ml of blood that is filtered. suppose that the body produces a constant amount of a substance x per unit of time. the kidneys eliminate substance x at a rate directly proportional to the concentration of the substance and the volume of blood cleared each minute (c): elimination = c × [x], where [x] is the steady-state concentration of substance x. imagine an individual with an initial concentration of x equal to [x]0 who develops kidney disease. her baseline clearance c0 drops to one half of the original (½c0). what is the new steady state concentration of x? (for simplicity, assume that substance x is 100% filtered by the kidney).