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This 14 page Class Notes was uploaded by AnnaClippinger on Tuesday September 22, 2015. The Class Notes belongs to BIOL-L211 2521 at Indiana University taught by Megan Dunn in Summer 2015. Since its upload, it has received 45 views. For similar materials see Molecular Biology in Biology at Indiana University.
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Date Created: 09/22/15
THEE 0 Lecture 5 Sep 33015 Last Time Properties of DNA Genome Organization Today Clickers enamel 4 Readinqwignmems The Cell Cy c e Bio 1 he pqleo 414 16116Lo1141 39 The Nucliepsome MR quot Next Time Reading Assignment Chapter 2 pp 2730 Chapter 9 pp 258 283 I Replica on Every cell maintains a certain number of chromosomes ampena s on ne 11m 0139 CE u mqlm 1 chromoiom t Beaeterzieilfe flii a 1 quot Chm mowme Jamied 1an flagele D u nuclaeid chmmpsome plasmid S eme ticreeWF quotPMquot Wquot DI PM i 5 golgi 39 Chromom me lo cared in Whamm R Bound Nuam i f reticulum wmitaehendlria hmp nid mil Haplm d Fig Sal Cell division Cell division involves R w Gwen of DNA in Par nf 11H Di srnoufiom of DNA 10 olauqm39a CLII S Occurs in Prokaryotes binar y ssi m li Somatic cells example epithelial Filmif silsili D xs 39 Occurs a5 part of a larger gell wrsl ei Cell division in bacteria Mane Jun each cell 3 3 SPEC l icgi f c 23 Chrom mama39s y No Du mam Gametes J Perm OI CE lmieiasisil Binary ssian ONT XU l on quot5 CUM 0 Cell replicates its DNA N Lid mid m fl The cytoplasmic 39 OW i 7 membraine l gngms c separating DNA molecules crass wall farms membrane invagi ates Cross wall farms completely Daughter cells 0 POEMcan gt 739 Ceipyrigm 926135 Pearsn Education inc pubilshing as Banjamin Cummings Cytoplasmic mem brane 39 Heplicated Cell division in eukaryotes Dividing epithelial cell taken by Jane Stout IU Shown in Times Square Somatic cell Any cell in an organism besides the gametes ii of Chromosomes 46 Zn diploid Gametes Egg and sperm of chromosomes 23 in haploid Mitosis OGCUFS l nJUmfl l lC LEI M Ln 1 0 1 wom Jno mum mam Chis Cells Meiosis occurs inqamtes in 101 TD a Di PlD lid 56 HQPlszli Moon39s hmiosis are PUY l D t GI W9quot 6 Wm B The somatic cell cycle V S l l u 0 DNA cm leg quotny WdlEr IJQd or lnterphase conSIsts ofG 5 and G phases 7 H r 39 The largerlpari new Ell 04cm dew dw d 613 PFC PG VE FOWCCH INTEHASE gt 5 Division WhE rwouacmmi Du Chm reamquot PL TE 5 l termmg 3 Slo PhOR 3 terminally Rainier 5 l DNA synthesis I 62 YEP C re c w 0 ClWlSIUHOl 46 C ll x i 3 V Mitosis Division ofthe nucleus distributes chromosomes to daughter nuclei 39 v Cytokines is Division of the co to lasm The nal products of M phase are two new daughter cells Throughout the cell cycle the structure of DNA changes Inter phate 5 phase Two major chromosomal events d ewndlensed repltceting a chromosomes lDNA repllcanen quot 7 a Vi nuclear membrane i 5 395 Hr CM 0 Md l39ld cone 3 ion i if Eltablimed Cohesion H39olds sister chromatids together Cohesin tilingshaped protein complexes encircle the two copies of recently replicated DNA In 0 mar F0 r DNA REPllgcgt ion EC 6 Earng GIQCOfnd Bh Std quot MaltQ surequot We Simer C h quotm M pH cls are least ecgme e 2 Du Pl i cutecl w Pie lt4 1 SISTU chromatidtquot initiation 9mm 2 5 raplicatl n replication establishment j utmhes 39 iOl39lA f s an Sl SfegrS blue strand 2 template DNA 31ng Fig811 Red strand duplicated copy 7quot l to s is P39rophase pr ophase 3quot metaphlase gt39 anaphase gt teloplhase gt cytekinesis sh 1 PCICk Down quotl1qt microtttblee r microtuble F WPhaSE i 1 grganizing 39 eehesin rings Nuclear envelope breaks down anlimtedlrister thmmosome Sis rev chgmgda Ch roma 6LT Endl of pr ophase a Chmmbsoma Replication Centrometa quotjg Ghromnsama hips amt Beginning of interphase Metaphase and anophose prophase 3 metaphase gt anaphase 39 telophase gt cytolkinesls metaphlase plate Meta hase l3 Chromosomes line lugp along tllhe he Iitp w monovalent attachment me an Else p a E lll mspmwr g gs I l 7 PM Bivalent attachment3951 39 5 01ch 1 0 Micro lme from 0p ijf blvalent attachment E eelearn 3 Pull haward Ema Pole proteolyzed Anaphase cohesion a Cohesins lproteolv zed Sl rtrChron1orl ds 39 w quot t hm mm H 0p osrfe Poles Pu39lll l amr39 cl 0 longer connected 139 Ensure moimm new nuclei c391 1 OF ne 5 l ser ch mm a 539 Telophose prophase gt metaphase 3 aanalphase gt telophase ogt cytokinesis Telophase a Each Chromosome at the spindle pole x 39 My raw 7 4 a lNluzclear envelope reforms NOT DFCONDENS ED w In EIOL l DNA decondenses as cell prepares NJ E l to resenterinterphase BOOK ls DE39C39ONDE39 D Note slslll shown in condensed lorm in drawing 39Ml l OSlS ls commere 10 Cytokinesis pzrophase metaphase 3quot anaphase telophase cytokinesis Cytokinesis Final separation oil the two daughter cell membranes and cytoplasm daughter cell daughter cell 11 A quick reminder as we transition from mitosis to meiosis Mitosis Occurs iii SM m c cells Zn to Zn produces daughter cells GluingFrom 15ers 0quot chromoxinmes 91 Meiosis Occurs irl 2n to In produces tquot j f dill leclgsghltercells Following replication are g rounds of chromosome segregation 12 nterphase 390 0quot me Jame as In milling DNA replication 7 i J i s rghmmwd co mm on interphase m 7 DNA replication lv 1 o l 7 J Prophasel Chromosomes condense hornole pairing ptop 659 I and remmoinallion Crossing over O CCUI S nonSfoerc hro 05 tbmolovrws Chromatomes f EE WEJEN 5 CH RC MATI M Allows 5151 c 39 oquotlrr s p sr of cro om Cl 139 SCI MEW One homologous pair shown blue AND yellow chromosomes one from each parent Homolog One o fthe chromosomes from the palr blue 0R yellow chromosome 13 Meiosis I Seporo 39on of homologous chromosomes MetaphaSe l albeitaphase plate 2 I OF 39 I ms ch on 7a m 39 Hahnquot o39 r02 a 1 0 an F dQW mamphggs m Homologs attach to mllcrotubules from opposite poles blue to one pole yellow to another monovalent attachment quotarrange on the Anaphase l arms a llitres kdowggf cohesion alon ol an J o WholCChromoSom l 39U fQi POKSDWPMWI Cohesron remains at centromeres Nquot mom telophase ll lterc 1 a mm Wigwam Fairs may a Telophase I and cytokii nesis Formation of ha lo39 392 drawing EOICnCll romotume has iJiSW chroma as HGPWH39 bauemmralls La HaIvc JUST 2 zhter cells fhmgh NOTSMOWH I H r 39 Prophase it not shown Chromosomes still composed of two sister chromatids mime n fix Ma Line 439 L1er Raddy to go 39I39hruM eta g Metaphase ll r K 4H Chromosomes align on me taphase plate as in E Ema 353quot 39 mitosis an T nsion a m om arms in draomw K quot u Sister chromatids attach to microtubules from Emphase a 39 opposite poles Anaphase ll Conesin breaks down four gametes or spores wistercnromo rids separate Move Wmd four genetically D ppon tc poles different daughter cells A big N 014 Tel ohase II and cytokinesis a A oat Nuclei form chromosomes begin to decondense and cytokinesis occurs 15 In the cell DNA is packaged into a chromosome 353m hr in Lecture IE ln eukaryotlc cells the average DNA strand Is 15 x103 nucleotides about 4 cm in length MUDX quotBeads on astring larger than the nucleus DNA must be be organized so that it can fit within the cell transmit efficiently to offspring and remain accessible for gene expression Chromatin complex of DNA and protein Histories 2 proteins that compact eukaryoric r quot 39 chromosomes absent m prorarvotesl Nuctleosome unit of DNA wrapped around a protein core composed of 8 histones TEN 39Ma w 39 c tm Metamaserhromosome 1 Eukaryotic chromosomes are compacted by h lStOHE S ls DNA negatively or positivey charged MC H Sens rs dong Why phat pme qroups on 3an have am cmer gt 39 Hist0nues are chargedhelpsglefErman H Chrgmmgmm are on er Gwensed ml mm or If a histone is positively charged will it interact more or less tightly with DNA More HalWm lll hle charge at l istomes is important since the structure If lDNlE yarles during the cell cycle inletphase Ml phase Nucleosomes Nucleasome A single DNAahistone ectamer core complex a mucleqsome Ll histone 1 Core DNA Core DNA Hemw GSSQ CJ M LI FL 39 V l core lxl 147 lel 39l he it DNA assoa akd H xxx y I g x 55 y l l l l I quot391 all F K 39 r 39 7 IE lk J x llnker DNA 20 50 hp Fig8 18 Linker DNA EMOh NWED SONIC 18 Histories F S abundant histone proteins Core histones comprise the octamer HZA HEB H3514 Linker histone H1not shown We 4COMQ it iIistonefold domain a Helps the core histories form an intermediate structure in the absence of DNA see next slide comm5 oFa HcIMJurn Helix TUm HeiiX HTHTI D Mg if a TypecF uFbld Mterminal tail H1 i histpnevefoid domain I ma N quotquot quotif quotquotquotquotquot c HIZE C li3 H14 Fig 8 19 u nswuaurcd UJDPS Tums 19 Assembly of a nucleosome X it fOFMvSa 26F mmc 1quotme W 5 H4 C n v It i 39Iquot 393 l gt r r l I 2 i 4 4 1quot a J M i H H39 Hai tetramer H2NH2B dimer 1 H3 and H4 form a tetramer iHZA and H28 form a dimer Hi3H4 tetramer binds dsDNA Q Double 5de Em 3 iiwo iIZAHZB dimers join the compiex The nucleosome is formed Fig 320 Modi cation of N termfnal histon e tails I 39II 1 r c DNA r r gt r If 7 Expand inns 4 variable N rqu N terminal tails of eaah histone are outside the DNA loop h be ma I39Fi d 7 0 Lhanqe ht tharqt 0 1m core Promm Htistome modi cations a TB REYEITIW Do NOT 0 the DNA Scenenot There are severe Jessibileposttra nslational medi rcah wons to histenresmwe ll discuss two wowd hrsrone mcmym on V6 Sult m cm increase or DEWECESE i m Tm ng39crfph om 0F suvrmma m eet5 2 D EC KEASE I H w Neutml eh cme of mfgmncg M0iIL S hIS39TOHES more h d i r H 1 remove macage A more Methyl group 3th In NUC l ug LO 39 quot 39 quot quotW11 ejNYmp realty Was No Lmrrae iHisrtone Methy Transferases HMTS Add methyl groups Me to histones Di ter in substrate speci city andgin number of methyl groups 2 or Eileen add i DECUNDENSE I you r V I f jj re m we the M em 3 mug Histome Demethylases HDMS Remove methyl groups 2 2 es gi 39l J 339 a 39 a 7 39 3m 1 Makes overall moqu ol Hi SmaneS mrc Ne f fiv Acetylation may help des condense chromosomes acCH3 g Removal of sacetvl groups from histones may ACEWI EFO UF promote eonQensatirin ENZY quot Histone Acetyltransferases HATS Add acetvl groups Ac to hlistones HDAC L ENZY ME Histone Deaeetvlases HDACS Remove acetyll groups 23 Histone modi cation a ects transcriptional regulation DNA compaction a39 iects accessibility of DNA binding proteins to regulatory regions Histone acetylation shown below Also true for methyla on phiosphorylation etc H is39lD ei acetylalion m illfai EE39l pillanal activation H istone doacetylation iguana silencing Genes can be turned off iftranscription factors can t get to these sites and vice versa Epigenemsz Req ulmm of he EXWS W Crimicol mod iF iteration of HiSl m a or 0F 24 Higher order remodeling of chromatin lllistone Hlil binds linker DNA 39 Erma Wi lhborm a Nuoleosomes cloScr m l Binols the Hammers Fig 3 29 30m Next level of compactio ber quot Stabilized by histone iii terminal tails quot Tiamthi w mm more Some Fig 3 31 Several additional levels of chromosome packaging occur but do not involve histoneis HistoneDNA interactions Many DNA binding proteins prefer binding to histone fr ee DNA a lo gt r 7 V How do these proteins gain access to histone free DNA q mmtd b Numg m HistoneaDNA association is not permanent it395 TEANSi Em Any region of DNA may be transiently released from interaction with histone octamer Slide x J39wa is Mon a i ap39eeedtlii ie li tment W A DNA unwraps from the nucleosome rather than briefly coming off39the nucleosomel protein hirian 51 Jl 39 9W site protein binding J W Protein binding sites become accessible Fig 8 34 HistoneDNA interactions Itipretein complexes that promote changes in nueleoseme location or NA interaction 39 Use ATP filigdrelysis L 7 Facilitate three types of changes 1 5 lid i it 2 E ction 3 Dimer existlarge protein binding xiiii I I kj39his pert en Hqu 3M4 quot 030123 39 m g I I lm 5 w Senletm39na 39e39l 0P uses 2 r HistoneDNA interactions Nucieosomes preferen aiiy form on DNA that bends easily AzT rich regigns in the m inorig move facing the histone octamer 39 a NTeond Unix mg 2 hqdm39ojm Ezomlg so it l o a rm n51 a PC LL eBUwit s NDT Sa umoe w d leaIcmL m 51 Cmmt 0 hrsi the marsme me E39 rd DNA or r0 Fig 888 However such sequences are NOT required for ntucleosome assembly H iston relJ N A i nte re cti 0 n J I t A News N39Ucl ogOMEs to Form alera WanHIE of Ch mmo 5 arm 28
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