USMLE Step 1 Pharmacology Comprehensive Review Questions with Correct Answers.

Michaelis-Menten Kinetics Correct Answer [S] = Concentration of substrate V = Velocity Km is inversely related to the affinity of the enzyme for its substrate Vmax = Directly proportion to the enzyme concentration Most enzymatic reactions follow of hyperbolic curve [Michaelis-Menten] kinetics Enzymatic reactions that exhibit a sigmoid curve [Hemoglobin] exhibit positive cooperativity Lineweaver-Burk Correct Answer ↑ y-intercept, ↓ Vmax The further to the right, the x-intercept [Closer to zero], the greater the Km, and the lower the affinity Enzyme Inhibition Correct Answer Reversible competitive inhibitors cross each other competitively, whereas nonreversible inhibitors do not [parallel] Reversible Competitive Inhibitiors Correct Answer Resemble Substrate: Yes Overcomed by ↑ [S]: Yes Binds Active Site: Yes Effect on Vmax: Unchanged Effect on Km: ↑ Pharmacodynamics: ↓ Potency Irreversible Competitive Inhibitors Correct Answer Resemble Substrate: Yes Overcomed by ↑ [S]: No Binds Active Site: Yes Effect on Vmax: ↓ Effect on Km: Unchanged Pharmacodynamics: ↓ Efficacy Noncompetitive Inhibitors Correct Answer Resemble Substrate: No Overcomed by ↑ [S]: No Binds Active Site: No Effect on Vmax: ↓ Effect on Km: Unchanged Pharmacodynamics: ↓ Efficacy