SnapShot:KeyNumbersinBiologyUriMoran,1RobPhillips,2andRonMilo11WeizmannInstituteofScience,Rehovot,Israel;2CaliforniaInstituteofTechnology,Pasadena,CA,USASeeonlineversionforlegendandreferences.1262Cell141,June25,2010©2010ElsevierInc.DOI10.1016/j.cell.2010.06.0191262.e1Cell141,June25,2010©2010ElsevierInc.DOI10.1016/j.cell.2010.06.019SnapShot:KeyNumbersinBiologyUriMoran,1RobPhillips,2andRonMilo11WeizmannInstituteofScience,Rehovot,Israel;2CaliforniaInstituteofTechnology,Pasadena,CA,USABiologyisbecomingincreasinglyquantitative.Takingstockofkeynumbersincellandmolecularbiologyenablesback-of-the-envelopecalculationsthattestandsharpenourunderstandingofcellularprocesses.Further,suchcalculationsprovideaquantitativecontextforthetorrentofdatafromnewexperimentaltechniques.However,suchusefulnumbersarescatteredinthevastbiologicalliteratureinawaythatoftenleadstoafrustratingliterature-miningordeal.Here,wehavecollectedasetofbasicnumbersinbiologythatwefindextremelyusefulforobtaininganorderofmagnitudefeelforthemolecularprocessesincells.Severalexamples(seebelow)showhowtocombinethesenumberstothinkaboutbiologicalquestions.Thevaluesshouldbeconsideredrulesofthumbratherthandefinitivevaluesasvarietyisthespiceoflifeandvariabilityiseverpresentinbiology.ThiscompilationisbasedontheBioNumberswikiproject(http://www.BioNumbers.org)wheretheseandthevaluesofseveralthousandotherbiologicalpropertiesareprovidedtogetherwiththeirexperimentalcontextandreferencestotheprimaryliterature.IsThereEnoughTimetoReplicatetheGenome?ThebacteriumEscherichiacolihasagenomeofroughly5millionbasepairs(bp)andareplicationrateintherangeof200–1000bp/s.Thesenumbersimplythatitshouldtakethetworeplisomesatleast2500storeplicatethegenome,anumberthatismuchlargerthanthemaximaldivisionrateof?20min.Howcanthisbe?Itturnsoutthat,underidealconditions,E.coliusesnestedreplicationforksthatbegintoreplicatetheDNAforthegranddaughterandgreatgranddaughtercellsbeforethedaughtercellshaveevencompletedreplication.HowManyMutationsina5mlCultureofBacter...
