Tutor profile: Faith B.
What combination of three medications often leads to Acute Kidney Injury (AKI)?
NSAIDs, loop diuretics, and ACE inhibitors all contribute to development of AKI, especially when given together. This is because loop diuretics decrease blood volume and therefore decrease perfusion to the kidney, while ACE inhibitors dilate the efferent renal arteriole and NSAIDs constrict the afferent renal arteriole so the glomerular filtration pressure is reduced.
What is one way to discern whether an enzyme inhibitor is competitive or non-competitive?
To figure out what type of inhibitor you have, you can experiment to figure out what the Michaelis-Menton enzyme kinetics are of each inhibitor. To do so, you can put the enzyme, natural substrate, and the inhibitor together to react. Run the reaction multiple times with increasing concentrations of substrate and measure enzyme kinetic parameters. Specifically, you can look at the Vmax (or maximum velocity) and the Km (or the concentration of substrate at 1/2 the Vmax). Competitive enzymes can be out-competed, so the Km will be higher but the Vmax will not change. A non-competitive enzyme cannot be out competed, so the Km will not change but the Vmax will be lower. The effect of the inhibitor on the enzyme kinetics can be looked at on Lineweaver Burke Plots.
How does Chargaff's Rule apply to the structure of DNA?
Chargaff's rule states that within double stranded DNA, the percent composition of cytosine will always be equal to the percent composition of guanine, and that the percent composition of thymine will always be equal to the percent composition of adenine. This is because cytosine, a pyrimidine, will always pair with guanine, a purine; and thymine, a pyrimidine, will always pair with adenine, a purine. Therefore, without mutations, there will always be equal amounts of purines and pyrimidines in double stranded DNA.
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