12Section I High-Yield ScienceBio/Biochem 1ENZYME KINETICSIn this lesson, you’ll learn to:·Explain the significance of key aspects of the double-reciprocal Lineweaver–Burk format,including axes, intercepts, units, and slopes·IdentifyVmaxandKMon both Michaelis–Menten and Lineweaver–Burk plots·Plot the effects of competitive inhibition on both graph typesEnzyme activity is often graphed using a Michaelis–Menten plot. However, enzyme activity may alsobe graphed using an alternative format, the Lineweaver–Burk plot. HMG-CoA reductase is the rate-limiting enzyme of cholesterol synthesis. Statins, such as atorvastatin (Lipitor), simvastatin (Zocor),and rosuvastatin (Crestor) are routinely used to treat patients with high cholesterol because they arecompetitive inhibitors of HMG-CoA reductase. How would the use of a statin affect the Lineweaver–Burk plot of HMG-CoA reductase?Michaelis–Menten PlotSubstrate Concentration [S]Reaction VelocityA Michaelis–Menten plot clearly shows the asymptotic behavior of a plot of an enzyme’s kinetics.What is the plot’s basic shape? How does it displayKMandVmax?Enzyme Kinetics are covered in:Biochemistry, Chapter 2: Enzymes
13Section I High-Yield ScienceBio/Biochem 1Lineweaver–Burk Plot(mM–1)1[S](s/μmol)1VA Lineweaver–Burk plot shows the same information as a Michaelis–Menten plot. How does it displayKMandVmax? What are the benefits of a Lineweaver–Burk plot, compared to a Michaelis–Menten plot?Why does a competitive inhibitor increase an enzyme’sKMwhile leaving itsVmaxunchanged?A competitive inhibitor will have the effect of increasing the slope of a Lineweaver–Burk plot. Why?
205LESSON 5.1Science Passage StrategyIn this lesson, you’ll learn to:·Preview a science passage at a glance, determininglikely topics and difficulty·Identify the most question-relevant information in ascience passage·Create efficient and useful passage outlinesScience Topics:·Intermolecular Forces·Organic Chemistry Reaction Analysis·Translational MotionMCAT STRATEGY—SCIENCE PASSAGESSCANFOR STRUCTUREDetermine your “gut feeling” about the passage with a quick previewREADSTRATEGICALLYRead the passage, focusing your attention on the more test-worthy detailsLABELEACH COMPONENTWrite down a short label or summary for each paragraph and figure as you readREFLECTON YOUR OUTLINEMake a full passage summary for yourself before moving to the questionsMCATScienceSkillsScientificReasoningand ProblemSolvingExperimentaland ResearchDesignData andStatisticalAnalysisScienceKnowledgeMCATExpertise