Biochemistry, Molecular Biology, and Genetics Todd A. Swanson, M.D., Ph.D. ResidentinRadiationOncology WilliamBeaumontHospital RoyalOak,Michigan Sandra I. Kim, M.D., Ph.D. DivisionofNuclearMedicineandMolecularImaging MassachusettsGeneralHospital Boston,Massachusetts Marc J. Glucksman, Ph.D. Professor,DepartmentofBiochemistryandMolecularBiology Director,MidwestProteomeCenter RosalindFranklinUniversityofMedicineandScience TheChicagoMedicalSchool NorthChicago,Illinois WITHEDITORIALCONSULTATIONBY Michael A. Lieberman, Ph.D. Dean,InstructionalandResearchComputing,UCit DistinguishedTeachingProfessor UniversityofCincinnati Cincinnati,OH AcquisitionsEditor:CharlesW.Mitchell ProductManager:StaceyL.Sebring MarketingManager:JenniferKuklinski Designer:HollyReidMcLaughlin Compositor:CadmusCommunications Printer:C&COffsetPrinting Copyright(cid:2)C 2010LippincottWilliams&Wilkins 351WestCamdenStreet Baltimore,MD21201 530WalnutStreet Philadelphia,PA19106 Allrightsreserved.Thisbookisprotectedbycopyright.Nopartofthisbookmaybereproducedinanyformorby anymeans,includingphotocopying,orutilizedbyanyinformationstorageandretrievalsystemwithoutwritten permissionfromthecopyrightowner. Thepublisherisnotresponsible(asamatterofproductliability,negligence,orotherwise)foranyinjuryresulting fromanymaterialcontainedherein.Thispublicationcontainsinformationrelatingtogeneralprinciplesof medicalcarethatshouldnotbeconstruedasspecificinstructionsforindividualpatients.Manufacturers’product informationandpackageinsertsshouldbereviewedforcurrentinformation,includingcontraindications, dosages,andprecautions. PrintedinHongKong FirstEdition,1990 SecondEdition,1994 ThirdEdition,1999 FourthEdition,2007 LibraryofCongressCataloging-in-PublicationData Swanson,ToddA. Biochemistry,molecularbiology,andgenetics/ToddA.Swanson,SandraI.Kim,MarcJ.Glucksman;with editorialconsultationbyMichaelA.Lieberman.—5thed. p.;cm.—(Boardreviewseries) Rev.ed.of:Biochemistryandmolecularbiology/ToddA.Swanson,SandraI.Kim,MarcJ.Glucksman.4thed. c2007. Includesbibliographicalreferencesandindex. ISBN978-0-7817-9875-4(hardcopy:alk.paper)1.Biochemistry—Examinations,questions,etc.2.Molecular biology—Examinations,questions,etc.I.Kim,SandraI.II.Glucksman,MarcJ.III.Lieberman,Michael,1950-IV. Swanson,ToddA.Biochemistryandmolecularbiology.V.Title.VI.Series:Boardreviewseries. [DNLM:1.BiochemicalPhenomena—ExaminationQuestions.2.BiochemicalPhenomena—Outlines. 3.GeneticProcesses—ExaminationQuestions.4.GeneticProcesses—Outlines.QU18.2S972b2010] QP518.3.S932010 572.8076—dc22 2009029693 Thepublishershavemadeeveryefforttotracethecopyrightholdersforborrowedmaterial.Iftheyhave inadvertentlyoverlookedany,theywillbepleasedtomakethenecessaryarrangementsatthefirstopportunity. Topurchaseadditionalcopiesofthisbook,callourcustomerservicedepartmentat(800)638-3030orfax ordersto(301)223-2320.Internationalcustomersshouldcall(301)223-2300. VisitLippincottWilliams&WilkinsontheInternet:http://www.LWW.com.LippincottWilliams&Wilkins customerservicerepresentativesareavailablefrom8:30amto6:00pm,EST. For Olga,Maxwell,Anneliese,andtheeagerlyawaited newadditiontotheSwansonclan. Ifnotforyou,allmyeffortswouldbeinvain. Preface This revision of BRS Biochemistry, Molecular Biology, and Genetics includes additional high-yieldmaterialtohelpthereadermasterclinicalprinciplesofmedicalbiochemistryas theypreparefortherevampedStep1USMLE.Ourgoalistoofferareviewbookthatboth laysthefoundationsofbiochemistryandintroducesclinicallyrelevantcorrelates.Indoing so,wehavede-emphasizedsomeoftherotememorizationofstructuresandformulasthat oftenobscurethebigpictureofmedicalbiochemistry.ClinicalCorrelatesineachchapter provide additional clinical insight, distilling numerous clinical correlations into a format that offersthe highest yield inreview. We hope that thesecorrelationswill help answera commonlyaskedquestion:‘‘Whydowehavetoknowthisfortheboards?’’ Thisrevisededitionalsoincludesanewchapterongeneticsasrelatedtomedicalbio- chemistry.Wehopethischapterwillaugmentotherreviewtextsongeneticsthatstudents mayconsultinpreparationforStep1. Manyofthequestionsattheendofeachchapterhavebeenrevisedtomaximizetheir valueforthestudentpreparingfortheexam.Acomprehensiveexamattheendofthisvol- umereinforcestheconceptsofthetext.Ourobjectivehasbeentoprovidethestudentwith clinicallyrelevantquestionsinaformatsimilartothatencounteredontheUSMLEStep1 Boards.ThebreadthofquestionsisoneofthemanyfeaturesofLippincott’sBoardReview Seriestitles. We hope that the new edition of BRS Biochemistry, Molecular Biology, and Genetics becomesavaluable toolforstudentsseeking high-yield resourcesastheyprepare forthe USMLEStep1.Werecognizethechangingnatureofscienceandmedicine,however,and encouragereaderstosendsuggestionsforimprovementforthistextorforourcompanion flashcards,tousviae-mailatLWW.com. ToddSwanson SandraKim MarcGlucksman v Publisher’s Preface The Publisher acknowledges the editorial consultation of Michael A. Lieberman, Ph.D., to this fifth edition. In addition to his role as editorial consultant on every chapter, Dr. Lieberman reviewed the entire manuscript to help ensure the accuracy, consis- tency, and timeliness of its content. vii