Download - Chuong 2-phan I
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CHNG II: GEN, GENOMICS V NHIM SC TH
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TS. Th Phc
Ging vin ca B mn Di truyn hc
in thoi: 01885881810
Email: [email protected]
THNG TIN V GING VIN
Email: [email protected]
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Thi gia k: bui cui cng ca chng 4
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1. H gen (genome)- H gen: kch thc h gen v phc tp ca s tin ha- H gen ca t bo nhn s- H gen ca t bo nhn chun
2. Nhim sc th: t chc phn t ca nhim sc th
NI DUNG CHNG II
2. Nhim sc th: t chc phn t ca nhim sc th- Cu trc ca nhim sc th vi rut, vi khun- Cu trc ca nhim sc th sinh vt nhn chun
3. Gen v cu trc gen- Khi nim gen v phn loi gen- Gen vi khun- Gen ca t bo nhn chun
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4. Cc yu t di truyn chuyn v- Yu t di truyn chuyn v trong h gen t bo nhn s- Yu t di truyn chuyn v trong h gen t bo nhn thc
5. Cc ADN ca c quan t- ADN ty th- ADN lc lp- ADN lc lp
6. H gen hc (genomics)- H gen hc cu trc (Structural genomics)- H gen hc chc nng (Functional genomics)- H gen hc so snh (Comperative genomics)
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H GEN (GENOME)
H gen (genome) l g?
H gen c phi l tp hp tt c cc gen?H gen c phi l tp hp tt c cc gen?
Tnh phc tp ca h gen c phn nh mc tin ha?
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H gen (genome) l tp hp cha ton b thng tin ditruyn m bo hot ng sng ca t bo, c th c m ha trong DNA ( mt s virus c th l RNA). H gen bao gm nhng vng cha gene ln nhng on khng phin m.
a s, h gen vi khun phn b trn mt NST dng vng
H GEN (GENOME)
a s, h gen vi khun phn b trn mt NST dng vngkhp kn v c kch thc nh.
i vi sinh vt nhn thc, 99% h gen nm trong nhn tbo v phn cn li nm trong mt s bo quan nh ty th, lc lp. H gen trong nhn t bo nhn thc thng rt lnv phn b trn cc NST dng thng.
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H gen sinh vt nhn thc c th chia ra:- H gen nhn (Nuclear genome)- H gen ty th (Mitochondrial genome)- H gen lc lp (Chloroplast genome)
H GEN (GENOME)
H gen ty th ngi H gen nhn ngi
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Kch thc h gen ca mt s sinh vt m hnh(model organisms)
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Cc gen phn b khng theo quy lut trong h gen.
Kch thc h gen khng phi lun t l vi tnh phc tpca loi. V d: H gen ca ngi c kch thc khong 3,3x109
bp, trong khi h gen cc loi lng c l khong 3,1x109 bp
C IM CA H GEN
bp, trong khi h gen cc loi lng c l khong 3,1x109 bphoc thc vt c th t n 1011 bp.
S lng NST cc loi rt gn nhau c th l rt khcnhau.
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SO SNH: H GEN SINH VT NHN S
V H GEN SINH VT NHN CHUNV H GEN SINH VT NHN CHUN
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H gen t bo nhn s H gen t bo nhn thc
Kch thc nh (95% l non-coding DNA.
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H GEN SINH VT NHN CHUNV d: vng nhm gen beta-globin ngi (y l vng cha nhiu gen ngigene-rich region) (a) v vng ~80-kb NST s 3 ca nm men (b)
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sinh vt nhn chun, s lng v loi gen m ha choprotein cc loi khc nhau l khc nhau.
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T CHC PHN T CA NST
di ca phn t ADN ln gp hng trm nhng nghn ln chiu di ca t bo. Vy, lmth no t bo c th cha phn t ADN? th no t bo c th cha phn t ADN?
ADN lin kt vi protein to nn cu trckhng gian c th, nhim sc th.
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CU TRC NST CA VIRUS
Virus: Phage T (T2, T4), phage MS2, virus khm thuc l, virus SV40
NST ca phage T l ADN trn, mch kp, khng chaprotein.protein.
Virus MS2: vt cht di truyn l phn tARN mch n. Virus SV40: NST l ADN mch vng kp vi 5224 cp bp.
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Phage T4
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CU TRC NST CA VI KHUN NST vi khun c cu trc hch nhn (nucleoid), nm trongt bo cht, cha khong 80% ADN h gen. Protein tham gia ng gi ADN trong cu trc hch nhnc tn l HU (cu trc khc histone nhng chc nng tngt). Hch nhn c th phn chia thnh khong 50-100 domain khc nhau, trng ging hnh bng hoa. Enzym ADN gyrase v ADN topoisomerrase c vai trtrong vic to cu trc hch nhn.
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CU TRC NST CA E.COLI
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NST CA SINH VT NHN THC Kiu nhn (karyote) l ton b s lng, hnh dng, kchthc NST trong nhn t bo ca mt loi sinh vt cquan st ti k gia nguyn phn.
B NST ca ngi.
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NST CA SINH VT NHN THC Protein tham gia chnh vo ng gi ADN l histone baogm: H1, H2A, H2B, H3 v H4; ngoi ra cn c cc non-histonprotein.
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Cu trc bc 1: polynuleosome(1nucleosome gm 8 phn t Histon von ADN 146 bp), ng knh 11 nm Cu trc bc 2: si nhim sc(solenoid), mi bc xon gm 6-8 nucleosome nh vai tr ca H1, ngnucleosome nh vai tr ca H1, ngknh 30-34 nm
Cu trc bc 3: nhim sc t(cromatid), c s tham gia ca non-histone protein (scaffold protein), ngknh 300nm 700 nm 1400 nm
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Cu trc ca nucleosome. Phn ui ca ccprotein histone c th hin ng nt t. S methyl ha v acetyl ha ui phn tprotein c lin quan n s ng/m xon casi nhim sc
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CENTROMERE V TELOMERE
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Tm ng (centromer):
L vng c trng cho NST ca sinh vt nhn thc
L iu kin tin quyt NST phn ly trong phn bo, l im nh NSTln si thoi v sc. Khi NST b t gy thnh 2 phn, trong mt phn chatm ng th ch c phn cha tm ng tn ti t bo con. Khi chuyn iv tr ca tm ng t NST ny sang NST khc th qu trnh phn bo caNST vi tm ng l khng b nh hng. Nh vy, trnh t nucleotide titm ng ch lin quan n nhim v m bo s phn ly chnh xc ca NST.tm ng ch lin quan n nhim v m bo s phn ly chnh xc ca NST.
Tm ng n gin nht l ca nm men (S.cerevisiae), gm 125 bp, chialm 3 vng tng ng I, II, III. Vng II l vng giu AT, vng I v III l v trbm ca phc hp protein (khong 30 protein), protein ny lin kt vi sithoi v sc.
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Tm ng (centromer):
Tm ng hu ht cc sinh vt nhn chuncha cc on ADN lp li lin tip. nm menS.pombe, tm ng c di khong 40 kb vi cctrnh t lp li. thc vt v ng vt, tm ngc th di ti vi Mb vi cc on lp li lin tip. ngi, on trnh t lp n gin di 171 bpc gi l alphoid v tm ng c chiu di 2-4c gi l alphoid v tm ng c chiu di 2-4Mb.
sinh vt bc cao, phc hp protein gn vitm ng c vai tr lin kt vi thoi v sc cgi l kinetochore.
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u mt (Telomere):
L cu trc nm u NST sinh vt nhn thc, bao gm cc trnh tADN khng c chc nng m ha, nhng lin quan n s bn vngca NST.
Trnh tADN ti u mt c th gm hai vng: Vng gn u mt gm 100-10000 on ADN ngn lp li lin tip;c th biu din di dng Cn(A hoc T)m, trong n>1 v m=1-4. Sln lp li ca Cn(A/T)m c th tng hoc gim sau mi ln phn bo.ln lp li ca Cn(A/T)m c th tng hoc gim sau mi ln phn bo. Trnh t tip theo l chui giu G-T dng si n di khong 14-16nu, c kh nng hnh thnh cu trc cp tc bo v u tn cng caNST
Trong qu trnh ti bn, u mt c duy tr nh enzym tolemerase.Nu t bo tin hnh phn chia m khng c enzym tolemerase th umt NST s b ngn dn qua cc ln phn bo, dn n s khng bnvng ca NST, NST d b t on hoc chuyn on. V vy, trong tbo ung th cc NST d thay i hnh dng, c kch thc nh.
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VNG D NHIM SC (HETEROCHROMATIN) VVNG NGUYN NHIM SC (EUCHROMATIN)
N: nhn con, n: hch nhn, vng m l vng d nhim sc
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VNG D NHIM SC (HETEROCHROMATIN) VVNG NGUYN NHIM SC (EUCHROMATIN) Quan st di knh hin vi in t cho thy si nhim scgm cc vng co m c hoc khng co c xen k lnnhau. Vng m c c gi l vng d nhim sc, vngkhng co c c gi l nguyn nhim sc.
Phn ln cc vng d nhim sc hu nh khng thay ingay c khi t bo bc vo phn chia, c gi l vng dnhim sc bo th (constitutive heterochromatin). Mt svng d nhim c th xut hin mi hoc bin mt khi tbo tri qua cc giai on sinh trng bit ha, c gi lvng d nhim bt n (facultative heterochromatin).
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VNG D NHIM SC (HETEROCHROMATIN) VVNG NGUYN NHIM SC (EUCHROMATIN)Hu ht cc gen phn b trong vng nguyn nhim sc.Cc ADN lp li v mt s rt t gen ( trng thi khnghot ng) phn b trong vng d nhim sc bo th.
S hnh thnh v duy tr vng d nhim sc ph thuc vomc methyl ha ca cytosine v histone, mc khmc methyl ha ca cytosine v histone, mc khacetyl ca histone. Khi loi b cc nhm methyl trn phnt ADN v histone th vng d nhim sc gin ra v mt sgen phn b trong vng c th c phin m.
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KHI NIM GENGen l g?
Gen l mt on acid nucleic cn thit cho stng hp ra mt sn phm c chc nng nhtnh (c th l chui polypeptit hoc l phn tARN)ARN)Nh vy, vng m ha cho protein (coding region) chc chn l thuc v gen. Cc vngiu ha nh enhancer, vng gn ui polyA, intron c thuc gen khng? Ti sao?
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KHI NIM GEN
Gen bao gm on acid nucleic cha m ditruyn (coding region) v on ADN (vng iukhin, regulatory elements) cn thit cho sphin m.
Gen gi l nhng on ADN c cu trc hay trnh t tng t gen nhng chng khng cphin m, hoc khng biu hin chc nng g.
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KHI NIM GENLm th no bit l gen hot ng?
Da vo sn phm ca gen, v d nghin cu sc mt, hm lng ca mARN bng Northern blot, RT-PCR, microarray; nghin cu ccprotein c mt trong t bo bng SDS-PAGE, protein c mt trong t bo bng SDS-PAGE, 2D gel electrophorensis
Transcriptome and proteome.
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SO SNH GEN SINH VT NHN S V NHN THCSinh vt nhn s Sinh vt nhn thc
Cc gen phn b gn nhau, khong cchgia cc gen ngn
Cc gen phn b xa nhau, ri rc trn ccNST
Cc gen tn ti dng n bn Gen n bn, gen thuc h gen
Gen khng b gin on bi intron Gen b gin on bi intron
Mt s gen phn b cnh nhau v chu Mi gen c mt vng promoter ringMt s gen phn b cnh nhau v chus iu khin chung bi mt promoter, c phin m sang cng mt phn tmARN. Cu trc ny gi l operon.
Mi gen c mt vng promoter ringbit.
Sn phm mARN thng lpolycistronic.
Sn phm mARN l monocistronic
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SP XP GEN SINH VT NHN S V NHN THC
Nm gen m ha cho protein enzymes cn thit cho con ng tng hp tryptophan
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CU TRC GEN SINH VT NHN THC
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PHN LOI GEN SINH VT NHN THC
C th phn loi gen ty theo s lng bn saoca gen c trong h gen, hoc theo chc nngca sn phm do gen m ha.ca sn phm do gen m ha.
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PHN LOI GEN SINH VT NHN THC
Gen n bn(single-copy gene)
Cc gen trong cng mt h gen (family gene): cc gen c trnh t nu v chc nng tng ng.
Gen lp li lin tc (tandem repeat genes): mt gen gm nhiu bn sao ging ht nhau lpli lin tc trn mt vng NST
Gen gi (pseudogene)
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CC GEN TRONG CNG MT H GEN Cc gen hnh thnh t mt gen t tin chung. Cc bn sao khng bt buc phi ging nhauhon ton. C ch hnh thnh nhiu bn sao ging hoctng t ca mt gen c th do sai lch trongtng t ca mt gen c th do sai lch trongtrao i cho gia hai NST tng ng tronggim phn. Cc gen trong h gen c th phn b tp trung(h gen m ha cho globin tp trung NST 11,, 16) hoc ri rc trn cc NST (h gen m hacho aldolase, 5 gen trn 5 NST khc nhau)
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CC GEN TRONG CNG MT H GEN Cc gen trong h gen thng hot ng nhng thi im nht nh v trong cc loi tbo bit ha khc nhau. Khi mt thnh vintrong h gen b bt hot, thnh vin khc c thc hot ha thay th, mc d bnh thngc hot ha thay th, mc d bnh thngthnh vin th 2 khng hot ng cng vi gen ban u.
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CC GEN LP LI LIN TC S lng bn sao lp li c th ln ti hngtrm bn, nhm p ng nhanh, vi s lngln sn phm ca gen trong iu kin nht nh. V d: cc gen m ha cho rARN c th lp liti hng trm bn p ng kp thi cc phnti hng trm bn p ng kp thi cc phnt ARN ribosome cho giai on sinh trngnhanh, cc gen m ha cho protein histonenhm cung cp histone cho qu trnh ti bnADN.
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CC GEN LP LI LIN TC
H gen ngi c khong 280 bn sao gen mha cho 3 loi rARN, tp trung thnh 5 vng(mi vng khong 50-70 bn copy), phn btrn 5 NST 13, 14, 15, 21, 22. trn 5 NST 13, 14, 15, 21, 22.
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CC GEN GI Gen gi khng to sn phm cui cng lprotein, mc d c th c phin m tng hpmARN. Cu trc c th ch gm ton exon, hoc c cexon-intron nhng thiu promoter. exon-intron nhng thiu promoter. Hu ht cc h gen u c gen gi, tuy nhins lng t.
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4. Cc yu t di truyn chuyn v- Yu t di truyn chuyn v trong h gen t bo nhn s- Yu t di truyn chuyn v trong h gen t bo nhn thc
5. Cc ADN ca c quan t- ADN ty th
NI DUNG BI HC TUN SAU
- ADN ty th- ADN lc lp
6. H gen hc (genomics)- H gen hc cu trc (Structural genomics)- H gen hc chc nng (Functional genomics)- H gen hc so snh (Comperative genomics)