T f T s T n sv I USTRUCTURE NUMBERSDNA GENOMES DNA deoxyribonucleicacid isthegeneticmaterialoflivingorganismsInhumansDNAisfoundinalmostallthecellsofthebody providestheinstructionstheyneedtogrowfunction respondtotheirenvironmentquickieNnooftedwhenacelldivides itpassesonacopyofitsDNAtoeachofitsdaughtercellsDNAisalsopassedonattheleveloforganisms wtheDNAinsperm eggcellscombiningtoformaneworganismthathasgeneticmaterialfrombothparents XXandXY noteDNAisalongstringofpairedchemicalunitsakanucleotidesthatcomein4differenttypes ATCGanditcarriesinfoorganizedintogenesLpgenesprovideinstructionsformakingproteinsGbgivecellsandorganismstheirfunctionscharacteristicsnuclearDNA DNAsolelyfoundinthenucleusineukaryoteslikeplantsanimalsmitochondrialDNA foundinmitochondria organellesthatharvestenergychloroplastDNA InchloroplastorganellesthatcarryoutphotosynthesisInbacteriamostoftheDNAisfoundin acentralregionofthecellcalledtheNUCleadwhichfunctionssimilarityto anucleusbutisnotsurroundedbyamembranegenome acell'ssetofDNADNAassociateswspecializedproteinsthatorganizeitandgiveitstructure Ineukaryotestheseproteinsincludethehistones agroupofbasicCtcharged proteinsthatformbobbinsaroundwhichnegativelychargedDNAcanwrapLahistoriesdeterminewhichgenesareactivethecomplexityofDNA thistonesandotherstructures chromatinchromatinis decondensed itexistsinlongthinstrings InthisstatetheDNACHROMATIN canbeassessedrelativelyeasilybycellularmachinery likeproteinsthatread4copyDNA whichisimportantinallowingthecelltogrow functionWHEN A CELL DIVIDES, ONE OF ITS MAIN JOBS ISTO MAKE SURE THAT EACH OF THE TWO NEWCELLS GETS A FULL, PERFECT COPY OF GENETICMATERIAL. MISTAKES DURING COPYING, ORUNEQUAL DIVISION OF THE GENETIC MATERIALBETWEEN CELLS, CAN LEAD TO CELLS THAT AREUNHEALTHY OR DYSFUNCTIONAL (AND MAYLEAD TO DISEASES LIKE CANCER) chromatincanalsobecondenseµcondensationtakesplacewhenthecellisabouttodivideWhenchromatincondensesyoucanseethateukaryoticDNAIsnotjustonelongstringbutisbrokenintoseparatelinearpiecescalledchromosomesCHROMOggMEg eachspecieshasItsowncharacteristicnumberofchromosomeshumanshave46 chromosomes in asomaticcellwhitedogshave78humansarediploid 2nqalutEEkeNnoothess ameansthatmostoftheirchromosomescomeinmatchedsetshomologiespairhave homogeneouspairsthesamegenesatthe the46chromosomesofahumancellareorganizedinto23pairsandsamelocationlocibut thetwomembersofeachpairarehomologuesofeachotherwillpossiblyhavediff humanspermandeggs onlyhave1homologouschromosomefromeachpairerentalleles genetic arehaploids Insequences pWhenaspermandeggfusetheirgeneticmaterialcombinestoformonecompletediploidsetofchromosomesforeachhomologouspairofchromosomesinyourgenomeoneofthehomologuescomesfromyourmom theotherfromdadthesexchromosomes XandY determines aperson'sbiologicalsex XX femaleandXY maleThesechromosomesaren'ttruehomologuesandareanexceptiontotheruleofthesamegenesinthesameplacestheXandYchromosomes aredifferent carrydifferentgenesautosomes 44nonsexhumanchromosomesCHROMOSOMESANDCELLDIVISIONasacellpreparestodivideitmustmakeacopyofeachofitschromosomessisterchromatids areidenticaltooneanother areattachedtooneanotherbyproteinscalledcohesionstheattachmentbetweensisterchromatidsisthetightestatthecentromerearegionofDNAthatisimportantfortheirseparationduringlaterstagesofcelldivisionaslongasthesisterchromatidsareconnected thecentromeretheyarestillconsideredtobeonechromosome Howeverassoonastheyarepulledapartduringcelldivisioneachis aseparatechromosome THECELLCYCLE Includes 2overlappingprocessesTHEMITOTICPHASE 1mitosis thenucleusanditscontents QUESTlON8divideevenlyinto2daughternuclei2cytokinesis thecytoplasmalongw a11 WHYDOCELLSPUTTHEIRtheorganellesisdividedin 2 CHROMOSOMESTHROUGHREPUthecombinationofmitosisandcytokinesis CATION CONDENSATION ANDproduces 2geneticallyidenticaldaughtercells SEPARATIONzTomakesurethatduringcellDIVISIONeachnewcellgetsexactlyonecopyofeachchromosome
