ScientificEnglishThestructureandfunctionoflargebiologicalmolecules(PartI)Macromolecules•Thecriticallyimportantlargemoleculesofalllivingthingsfallintojustfourmainclasses:carbohydrates,lipids,proteins,andnucleicacids.•Onthemolecularscale,membersofthreeoftheseclasses--carbohydrates,proteins,andnucleicacids--arehugeandarethereforecalledmacromolecules.Concept1Macromoleculesarepolymers,builtfrommonomers•Apolymer(fromtheGreekpolys,many,andmeros,part)isalongmoleculeconsistingofmanysimilaroridenticalbuildingblockslinkedbycovalentbonds,muchasatrainconsistsofachainofcars.•Therepeatingunitsthatserveasthebuildingblocksofapolymeraresmallermoleculescalledmonomers(fromtheGreekmonos,single).•Someofthemoleculesthatserveasmonomersalsohaveotherfunctionsoftheirown.TheSynthesisandBreakdownofPolymers•Monomersareconnectedbyareactioninwhichtwomoleculesarecovalentlybondedtoeachother,withthelossofawatermolecule;thisisknownasadehydrationreaction.•Onemonomerprovidesahydroxylgroup(-OH),whiletheotherprovidesahydrogen(-H).•Polymersaredisassembledtomonomersbyhydrolysis,aprocessthatisessentiallythereverseofthedehydrationreaction.•Hydrolysismeanstobreakusingwater(fromtheGreekhydro,water,andlysis,break).•Anexampleofhydrolysisworkingwithinourbodiesistheprocessofdigestion.•Thebulkoftheorganicmaterialinourfoodisintheformofpolymersthataremuchtoolargetoenterourcells.Withinthedigestivetract,variousenzymesattackthepolymers,speedinguphydrolysis.•Thereleasedmonomersarethenabsorbedintothebloodstreamfordistributiontoallbodycells.Thosecellscanthenusedehydrationreactionstoassemblethemonomersintonew,differentpolymersthatcanperformspecificfunctionsrequiredbythecell.TheDiversityofPolymers•Eachcellhasthousandsofdifferentmacromolecules;thecollectionvariesfromonetypeofcelltoanothereveninthesameorganism.•Theinherentdifferencesbetweenhumansiblingsreflectsmallvariationsinpolymers,particularlyDNAandproteins.•Moleculardifferencesbetweenunrelatedindividualsaremoreextensiveandthosebetweenspeciesgreaterstill....
