-
ADNmonocatenar(mc)
unelevirusuri,deex.parvovirusuri
ADNdublucatenar(dc)
circularcircular
linearlinear
Cromozombacterian,Plasmidebacteriene
Cromozomidelaeucariote
ADNdcADNdccircularcircular
delavirusulSV40delavirusulSV40 ADNdcADNdccircularcircular
dinmitocondriiumanedinmitocondriiumane
ADNdclinearumaninreplicareADNdclinearumaninreplicare
De la ADN la cromozomiDe la ADN la cromozomi
Unelevirusuri
ADNmitocondrial,ADNcloroplastic
CromozomlaCromozomlaE.coliE.coli
PlasmidelaPlasmidelaE.coliE.coli
Unelevirusuri
-
Cuvntulcromozom:chroma
=culoare,soma
=corp cromozom=corpcolorat
n celule, moleculele de ADN sunt asociate cu proteinen celule,
moleculele de ADN sunt asociate cu proteine
Fiecare molecul ADN Fiecare molecul ADN + proteinele asociate =
cromozom, + proteinele asociate = cromozom, i la PK, i la PK, i la
EK i la EK
mpachetareaADNmpachetareaADNuluiuluincromozomincromozomindeplinendeplinetemaimultefunctemaimultefuncii:ii:
ADNADNulcelulararedimensiunemaimaredectcelulaulcelulararedimensiunemaimaredectcelula
ptraptrancpeancpeancelulncelul,ADN,ADNultrebuiecompactatultrebuiecompactat
mpachetareaADNmpachetareaADNuluiuluiiasociereacuproteineprotejeazfaiasociereacuproteineprotejeazfadealterridealterri
DoarDoarnformcompactatnformcompactatncromozomi,ADNncromozomi,ADNulpoatefitransmiseficientulpoatefitransmiseficientiegallacele2celulefiiceiegallacele2celulefiice
ADNADNulnudestedestuldeinstabilulnudestedestuldeinstabilncelule,spredeosebiredecromozomi,caresuntmultmaistabilncelule,spredeosebiredecromozomi,caresuntmultmaistabilii
CrzconferoorganizareglobalfiecreimoleculedeADNCrzconferoorganizareglobalfiecreimoleculedeADN,o,organizarececonferrganizarececonferiaccesibilitatectreADNiaccesibilitatectreADN
De la ADN la cromozomiDe la ADN la cromozomi
dinmasaunuicrzEK=proteinedinmasaunuicrzEK=proteine
CromatinCromatin=regiunidinADNasociatecuproteine=regiunidinADNasociatecuproteine
MajoritateaproteinelorasociatecumoleculeledeADN=proteineMajoritateaproteinelorasociatecumoleculeledeADN=proteine
cug.m.cug.m.mmicic,bazice,bazice
HISTONEHISTONEAlteproteineasociatecuADN:AlteproteineasociatecuADN:NONNONHISTONEHISTONEregleazreplicarearegleazreplicarea,repararea,recobinarea,repararea,recobinareaitranscriereaitranscrierea
PrimulrolimprotantalproteinelorasociatecuADN,PrimulrolimprotantalproteinelorasociatecuADN,nmodspecialalhistonelor,estecompactareamoleculelordeADNnmodspecialalhistonelor,estecompactareamoleculelordeADN
Deex:Deex: grosimeamedieauneipb=3,4grosimeamedieauneipb=3,4
1c1celulumanconelulumanconine3x10ine3x1099
pb/sethaploid,pb/sethaploid,~ ~ 10101010
~ ~ 1m1m 1cel.are1cel.arennucleu(nnucleu(
=10=1015mm)2mdeADN15mm)2mdeADN
-
MajoritateaPKau1cromozomMajoritateaPKau1cromozom=1=1moleculdeADNdmoleculdeADNd.c.circular.c.circular
OrganismeleseOrganismelesenmulnmulescprindiviziunecelularsimplescprindiviziunecelularsimpl
fisiunebinarfisiunebinar
Fiecare celul are un anumit numr, specie-specific, de
cromozomi
PK PK
EK EK
CromozomulbacterianCromozomulbacterian
nucleoidnucleoid
NuexistmembrannuclearNuexistmembrannuclearnuexistnucleunuexistnucleu
PKpotaveaPKpotaveaiplasmide(moleculeADNdc,deobiceicirculare)iplasmide(moleculeADNdc,deobiceicirculare)
MajoritateacelulelorEKsuntMajoritateacelulelorEKsuntDIPLOIDEDIPLOIDE:aucte2exemplaredinfiecarecrz,darcele2exemplarenus:aucte2exemplaredinfiecarecrz,darcele2exemplarenusuntidenticeuntidentice
DiploidiaasigurDiploidiaasigurnmulnmulireadetipsexuatireadetipsexuat
aorganismelorEKaorganismelorEK
gamegameiiauiiau
nr.crznr.crz
NumrpardecromozomiNumrpardecromozominnucleu(nnucleu(2n),2n),fiecarecrz=1molfiecarecrz=1moleculADNdeculADNd.c.linear.c.linear
OrganismeleEK(majoritatea)seOrganismeleEK(majoritatea)senmulnmulescprinreproduceresexuatescprinreproduceresexuat
Celule2nCelule2n GameGameiinnmeiozmeioz fecundafecundaieie
unireaa2gameunireaa2gameii Celule2nCelule2n
nmitocondrii,cloroplastenmitocondrii,cloroplaste
cte2cte210moleculeADNdccircularADNmt10moleculeADNdccircularADNmt
ADNextracromozomal:ADNextracromozomal:
ADNextracromozomal:ADNextracromozomal:
(cte1exemplardinfiecaretipdecrz)
-
p l i e r e
su p r a r a su c i r e
c i r c a 5 0 d o m e n i ip e r c r o m o so m
b a c t e r i a n
c r o m o so mb a c t e r i a n
d o m e n i isu p r a sp i r a l i z a t e
n e g a t i v
R E P
R E P
A D N g i r a z a
Cromozomul la procariote PK
proteine histonehistone--likelike
: HU (Helix-Unwinding)
-
Cromozomul la eucariote
-
Dimensiune genom Dimensiune genom [Mpb] [Mpb] Forma crzForma
crz
Nr.crz. /Nr.crz. /set haploidset haploid
Nr.seturi Nr.seturi haploidehaploide
Nr.total Nr.total crzcrzSPECIESPECIE
P R O C A R I O T EP R O C A R I O T E
4,64,6circularcircular111111Escherichia coliEscherichia coli
2,82,8circularcircular111111Staphylococcus aureusStaphylococcus
aureus
circularcircular221122Vibrio choleraeVibrio cholerae
5,75,73 C, 1 L3 C, 1 L441144Agrobacterium
tumefaciensAgrobacterium tumefaciens
E U C A R I O T EE U C A R I O T E
12,112,1linearlinear16161 sau 21 sau 23232Saccharomyces
cerevisiaeSaccharomyces cerevisiaedrojdia de beredrojdia de
bere
9797linearlinear66221212Caenorhabditis elegansCaenorhabditis
elegans
125125linearlinear55221010Arabidopsis thalianaArabidopsis
thaliana
15 00015 000linearlinear88221616Allium cepaAllium cepa
45004500linearlinear77221414Pisum sativumPisum
sativummazremazre
180180linearlinear442288Drosophila melanogasterDrosophila
melanogaster
26002600linearlinear2020224040Mus musculusMus musculus
25002500linearlinear1919223838Felis catusFelis catuspisica
domesticpisica domestic
24002400linearlinear3939227878Canis familiarisCanis
familiariscinecine
27002700linearlinear1919223838Sus scrofaSus scrofaporc
domesticporc domestic
27002700linearlinear2727225454Ovis ariesOvis ariesoaieoaie
29002900linearlinear3030226060Bos taurusBos taurusvaca
domesticvaca domestic
26002600linearlinear3232226464Equus caballusEquus
caballuscalcal
29002900linearlinear2424224848Gorilla gorillaGorilla gorilla
33003300linearlinear2424224848Pan troglodytesPan troglodytes
32003200linearlinear2323224646Homo sapiensHomo sapiens
-
Organismelemaicomplexeaudensitategenicsczut
-
NUCLEOZOMULNUCLEOZOMUL
nceluleleEK,nceluleleEK,majoritateacantitmajoritateacantitiiADNesteiiADNestempachetatmpachetatnnNUCLEOSOMINUCLEOSOMINucleosom=miezde8proteinehistonice+regiuneaADNNucleosom=miezde8proteinehistonice+regiuneaADNnfnfuraturatnjurullornjurullor
AspectdemrgelepeunfirAspectdemrgelepeunfir
ADNADNuldintre2nucleosomiadiacenuldintre2nucleosomiadiaceni=i=ADNlinkerADNlinker(de(delegturlegtur))
Prinasamblare/Prinasamblare/mpachetarempachetarennucleosomi,nnucleosomi,ADNADNulsescurteazdeulsescurteazde6ori6ori
Asamblarea/Asamblarea/mpachetareampachetareannucleosomi=nnucleosomi=primaetapprimaetapieseniesenialialncompactareaADNncompactareaADNuluiului
H2AH2A
H2BH2B
H3H3
H4H4
ADNADNnfnfuraturatnjurulunuioctamerhistonicnjurulunuioctamerhistonic~~147pb,de1,7ori147pb,de1,7ori
-
HistoneHistonele=proteinemici,le=proteinemici,ncrcatepozitivncrcatepozitiv
HistoneleHistonele
=celemaiabundenteproteineasociatecuADNlaEK=celemaiabundenteproteineasociatecuADNlaEK
5tipuri:5tipuri:
H1,H2A,H2B,H3,H4H1,H2A,H2B,H3,H4
histonelemiezhistonelemiez
2x[H2A,H2B,H3,H4]=MIEZULNUCLEOSOMULUI2x[H2A,H2B,H3,H4]=MIEZULNUCLEOSOMULUI
1x1xHH1s1seleaglaADNeleaglaADNullinker,dintre2nucleosomiullinker,dintre2nucleosomi
proteinemici,proteinemici,ncrcatepozitivncrcatepozitiv(con(coninutridicatinutridicatnAAnAAncrcatpozitivncrcatpozitiv))
111115KDa15KDa
H2H2H4H421KDa21KDa
H1H1
-
MiezulproteicalnucleosomuluiareformdediscMiezulproteicalnucleosomuluiareformdedisc
nsolunsoluie,cie,cele4tele4tipuridehistoneseasambleazastfelipuridehistoneseasambleazastfel::
H2A+H2BH2A+H2B heterodimerH2AheterodimerH2AH2BH2B
H3+H4H3+H4 heterodimerH3heterodimerH3H4H4
2heterodimeriH32heterodimeriH3H4H4 tetramerH3tetramerH3H4H4
-
AsamblareaunuinucleosomesterealizatAsamblareaunuinucleosomesterealizatntrntroanumitordineoanumitordine::
H3+H4H3+H4 heterodimer[H3heterodimer[H3H4]H4]
2x[H32x[H3H4]H4] tetramer4[H3tetramer4[H3H4]H4]
1tetramer4[H31tetramer4[H3H4]seataH4]seataeazlaADNeazlaADN
2heterodimeri[H2A2heterodimeri[H2AH2B]seataH2B]seataeazlaacestcomplexeazlaacestcomplex
NUCLEOSOMNUCLEOSOM
H2A+H2BH2A+H2B heterodimer[H2Aheterodimer[H2AH2B]H2B]
1.Dimerizareahistonelor1.Dimerizareahistonelor
2.Ini2.Iniiereanucleosomuluiiereanucleosomului
3.3.TerminareaformriinucleosomuluiTerminareaformriinucleosomului
H2AH2A
H2BH2B
H3H3
H4H4
-
STRUCTURACROMATINEISTRUCTURACROMATINEI
EucromatinEucromatinaaiHeterocromatinaiHeterocromatina
HistonHistonaa
H1H1seleaglaADNlinkerdintrenucleosomiseleaglaADNlinkerdintrenucleosomi
OdatformaOdatformainucleosomii,inucleosomii,urmtareaetapurmtareaetapnnmpachetareamoleculelormpachetareamoleculelor
deADN=legareahistoneiH1deADN=legareahistoneiH1
H1H1=o=oproteinmicproteinmic,,ncrcatpozitivncrcatpozitiv,s,seleaglaADNeleaglaADNuldintrenucleosomiuldintrenucleosomi
nacestmod,nacestmod,HH1s1stabilizeazasociereaADNtabilizeazasociereaADNuluicuproteineleuluicuproteinele
nucleosomalenucleosomaleideci,ideci,stabilizeazstructuranucleosomuluistabilizeazstructuranucleosomului
SeleaglaADNSeleaglaADNn2zone:n2zone:
ozonesteexactozonesteexactnafaraunuinucleosomnafaraunuinucleosom
ozonesteregiuneacentraldeozonesteregiuneacentraldenfnfurareaADNurareaADNnjurulhistonelormieznjurulhistonelormiez
secoloreazmaislabsecoloreazmaislab
estemaiactivcaratdetranscriereestemaiactivcaratdetranscriere
secoloreazmaiintenssecoloreazmaiintens
estemaipuestemaipuinactivcaratdetranscriereinactivcaratdetranscriere
Chiar i n interfaz, nu toat cromatina are acelai grad de
condensare :
n interfaz
materialul genetic
: -
este structurat sub form de CROMATIN-
cromozomii nu sunt
vizibili la microscop
Cele 23 de perechi de cromozomi umani ocup anumite teritorii n
nucleu
EUCROMATINAEUCROMATINA HETEROCROMATINAHETEROCROMATINA
-
AdugareahistoneiHAdugareahistoneiH11
unnivelsuperiordecompactareaADNunnivelsuperiordecompactareaADNuluiului
-
UrmtoareaetapdecompactareUrmtoareaetapdecompactare=FIBRADE30nm=FIBRADE30nm
EvidenEvideniatiatiiinvitroinvitro
iiinvivoinvivo
2m2modeledestructurafibreideodeledestructurafibreide30nm30nm
ModelulModelulSOLENOIDSOLENOID
SeformeazunsuperhelixceconSeformeazunsuperhelixceconine6nine6nucleosomiperspirucleosomiperspirADNADNullinkersegseullinkersegsetespreinteriorulsuperhelixului,darNUtreceprinaxulcentratespreinteriorulsuperhelixului,darNUtreceprinaxulcentralalacestuialalacestuiaZoneledeZoneledeintrareintrare
iiieieireire
aADNdinnucleosomiNUsuntaccesibileaADNdinnucleosomiNUsuntaccesibile
ModelulModelulZIGZAGZIGZAG
ADNADNullinkerTRECEprinaxulcentralalsuperhelixuluiullinkerTRECEprinaxulcentralalsuperhelixului
accesibileaccesibilemaimaiaADNdinnucleosominusuntaADNdinnucleosominusuntireireieieiiintrareintrareZoneledeZonelede
SeformeazunsuperhelixceconSeformeazunsuperhelixceconine4nine4nucleosomiperspirucleosomiperspir
LungimeaADNLungimeaADNuluilinkeruluilinker
variazvariaz(distan(distanaa
dintre2nucleosomi)dintre2nucleosomi)
RegiunileculinkermailungRegiunileculinkermailung
(deci(decicudensitatemaicudensitatemai
micdenucleosomimicdenucleosomi)a)aii
fibreide30nmfibreide30nmauau
structurZIGZAGstructurZIGZAG
ntrntrunacelaunacelainucleuseinucleuse
potpotntlnintlninsimultannsimultan
ambeleformeambeleforme
-
RegiunileaminoRegiunileaminoterminalealehistonelorsuntnecesareptrformareafibrei30nmterminalealehistonelorsuntnecesareptrformareafibrei30nm
CozileaminoCozileaminoterminalealehistonelornucleosomale(H2A,H2B,H3,H4)interacterminalealehistonelornucleosomale(H2A,H2B,H3,H4)interacioneazcunucleosomiiadiacenioneazcunucleosomiiadiacenii
-
UrmtoareaetapUrmtoareaetapncompactareaADN=formareadebuclemarincompactareaADN=formareadebuclemari
Formareanucleosomilor+formareafibrei30nmFormareanucleosomilor+formareafibrei30nm
compactareaADNcuscurtarepcompactareaADNcuscurtarepnladenlade40deori40deoriEsteEstencinsuficientncinsuficientestenecesarcompactareamaiputernicaADNestenecesarcompactareamaiputernicaADNModel:Model:
Fibra30nmFibra30nmformeazbuclemariformeazbuclemari,de40,de4090kpb,90kpb,inutedeostructurproteicdenumitNUCLEARSCAFFOLDinutedeostructurproteicdenumitNUCLEARSCAFFOLD
(traducere(traducereadliteramadliteram:s:schelnuclearchelnuclear))
2clasedeproteine:2clasedeproteine:TopoIITopoII:l:labazafiecreibucleabazafiecreibucle,men,menineformabuclatineformabuclat;buclelesunttopoizomeri;buclelesunttopoizomeri
ProteineSMC(StructuralMaintenanceofChromosome)ProteineSMC(StructuralMaintenanceofChromosome)
SeformeazfibradecromatinSeformeazfibradecromatin=s=structurdebazacromozomilortructurdebazacromozomilor
MBOGMBOG
NucleosomeAssemblyNucleosomeAssembly
-
StructuracromozomilorseschimbdeStructuracromozomilorseschimbdealungulcicluluicelularalungulcicluluicelular
GraduldecondensareamaterialuluigeneticvariazGraduldecondensareamaterialuluigeneticvariazntimpulunuiciclucelularntimpulunuiciclucelular
InterfazInterfazcondensaremairedusamaterialuluigeneticcondensaremairedusamaterialuluigenetic,permitetranscriere,replicare,reparare,permitetranscriere,replicare,reparare
DupreplicareDupreplicare,moleculelefiice:,moleculelefiice:
asamblarenucleosomiasamblarenucleosomi
coeziuneacromatidelorsuroricoeziuneacromatidelorsurori
complexproteicdenumitcomplexproteicdenumitcoezincoezin
formareafibrei30nmformareafibrei30nm
ninterfaznusevdcromozomiicaentitninterfaznusevdcromozomiicaentitidistinctecitologic;suntvizibiledoarblocuricromaticeidistinctecitologic;suntvizibiledoarblocuricromaticecromatincromatin,,
unelecoloratemaislabunelecoloratemaislabeucromatineucromatin,a,altelecoloratemaiintensltelecoloratemaiintensheterocromatinheterocromatin
-
ProfazProfazcontinucondensareacromatineicontinucondensareacromatinei(deci,amaterialuluigenetic)(deci,amaterialuluigenetic)
(procesulsemainume(procesulsemainumeteteiicondensareacromozomilorcondensareacromozomilor))
formareacromozomilorcaentitformareacromozomilorcaentitii
vizibilelamicroscopvizibilelamicroscop
LasfrLasfrituldiviziuniicelularereituldiviziuniicelularerencepeprocesuldedecondensareancepeprocesuldedecondensarea
cromozomilor,pnalagracromozomilor,pnalagraduldefibrdecromatinduldefibrdecromatin,,
ichiarpnlafibraichiarpnlafibra3030nm,10nm,10nmnm
-
DEZASAMBLAREA/ASAMBLAREANUCLEOSOMILORnreplicareaADN
NucleosomiisuntNucleosomiisunt
dezasambladezasamblaipemoleculaparentalipemoleculaparental,,nfanfaabifurcaabifurcaieidereplicareieidereplicare
asamblaasamblaipemoleculelefiice,ipemoleculelefiice,nordineaanteriorprezentatnordineaanteriorprezentat
TetrameriiH3TetrameriiH3H4H4vechivechirmnasociarmnasociaicuicu
moleculaADNmoleculaADNitreccaatare,itreccaatare,fielaunafielauna
dinmoleculelenoi,fdinmoleculelenoi,fielacealaltielacealalt
DimeriiH2ADimeriiH2AH2BH2Bvechivechi
sedesprinddepesedesprinddepe
ADNADNitrecitrecntintinsolunsoluie.ie.
-
DereDereinutinut
-
Diagram of a replicated and condensed metaphase
eukaryotic chromosome.(1)
Chromatid
one of the two identical parts of the chromosome after S phase.
(2)
Centromere
the point where the two chromatids touch, and where the
microtubules attach.(3)
Short arm.(4)
(4) Long arm.
Human chromosomes during metaphase.
G1 1 cromozom = 1 molecul ADN = 1 cromatid Cromozom
monocromatidic
S Replicare ADN = dublarea cantitii de ADN
G2 1 cromozom = 2 molecule ADN identice = 2 cromatide surori
Cromozom bicromatidic
-
Molecula ADN este complexat cu proteine
Rolul histonelor
stabilitatea i protecia moleculelor de ADNmpachetarea
moleculelor ADNStructurarea cromatinei i a cromozomilorMediaz
aciunea altor proteine pe molecula ADN
proteine ptr replicarea, exprimarea ADN
-
Alfabet grecesc Alfabet grecesc
Se citeteLiter micLiter mareSe citeteLiter micLiter mare
niualfaksibetaomicrongamapideltarho
(ro)epsilonsigmazetatauetaipsilon thetaphi (fi)iotachi
(hi)kappapsilambdaomegamiu
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