Tom qab kev tshawb pom ntawm lub hauv paus ntsiab lus ntawm lub koom haum molecular ntawm cov khoom xws li DNA hauv xyoo 1953, molecular biology pib tsim. Tsis tas li ntawd, nyob rau hauv cov txheej txheem ntawm kev tshawb fawb, cov kws tshawb fawb pom tias DNA yog recombined, nws muaj pes tsawg leeg thiab peb cov tib neeg genome ua haujlwm li cas.
Txhua hnub, cov txheej txheem nyuaj tshwm sim ntawm qib molecular. DNA molecule tau npaj li cas, nws muaj li cas? DNA molecules ua lub luag haujlwm dab tsi hauv lub cell? Wb tham kom ntxaws txog tag nrho cov txheej txheem uas tshwm sim hauv ob txoj saw.
Cov ntaub ntawv keeb kwm yog dab tsi?
Yog li nws pib li cas? Thaum ntxov li 1868, nucleic acids tau pom nyob rau hauv cov kab mob ntawm cov kab mob. Thiab nyob rau hauv 1928, N. Koltsov muab tso rau pem hauv ntej txoj kev xav hais tias nws yog nyob rau hauv DNA hais tias tag nrho cov genetic ntaub ntawv hais txog ib tug muaj sia nyob yog encrypted. Tom qab ntawd J. Watson thiab F. Crick pom tus qauv rau tam sim no paub zoo DNA helix hauv 1953, uas lawv tsim nyog tau txais kev lees paub thiab khoom plig - Nobel nqi zog.
DNA yog dab tsi? Cov khoom no yog tsim los ntawm 2ua ke threads, ntau precisely spirals. Ib ntu ntawm cov saw txuas nrog qee cov ntaub ntawv hu ua noob.
DNA khaws tag nrho cov ntaub ntawv hais txog hom proteins twg yuav tsim thiab nyob rau hauv qhov kev txiav txim. DNA macromolecule yog cov khoom thauj khoom ntawm cov ntaub ntawv muaj txiaj ntsig zoo kawg nkaus, uas tau sau tseg hauv cov kab ke nruj ntawm ib tus neeg lub tsev thaiv - nucleotides. Muaj 4 nucleotides nyob rau hauv tag nrho, lawv ntxiv ib leeg chemically thiab geometrically. Lub hauv paus ntsiab lus ntawm kev ua kom tiav, lossis kev ua tiav, hauv kev tshawb fawb yuav piav qhia tom qab. Txoj cai no ua lub luag haujlwm tseem ceeb hauv kev encoding thiab txiav txim siab cov ntaub ntawv caj ces.
Vim tias DNA strand ntev ntev heev, tsis muaj qhov rov ua dua hauv cov kab ke no. Txhua yam muaj sia muaj nws tus kheej DNA strand.
DNA ua haujlwm
Cov haujlwm ntawm deoxyribonucleic acid suav nrog kev khaws cov ntaub ntawv keeb kwm yav dhau los thiab nws kis mus rau cov xeeb ntxwv. Yog tsis muaj txoj haujlwm no, lub genome ntawm ib hom tsis tuaj yeem khaws cia thiab tsim tau ntau txhiab xyoo. Cov kab mob uas tau dhau los ua cov noob hloov pauv loj dua yuav tsis muaj sia nyob lossis poob lawv lub peev xwm los tsim cov xeeb ntxwv. Yog li ntawd muaj kev tiv thaiv ntuj tiv thaiv degeneration ntawm hom.
Lwm txoj haujlwm tseem ceeb yog kev siv cov ntaub ntawv khaws cia. Lub xovtooj ntawm tes tsis tuaj yeem ua cov protein tseem ceeb yam tsis muaj cov lus qhia khaws cia hauv ob txoj hlua.
YComposition ntawm nucleic acids
Tam sim no nws twb paub tseeb tias lawv tus kheej muaj dab tsiNucleotides yog lub tsev blocks ntawm DNA. Lawv muaj 3 yam khoom:
YOrthophosphoric acid.
Tus naj npawb ntawm nucleotides ib txwm sib npaug rau cov lej ntawm nitrogenous hauv paus. Hauv cov chaw kuaj mob tshwj xeeb, ib qho nucleotide yog cleaved thiab lub hauv paus nitrogenous yog cais los ntawm nws. Yog li lawv kawm txog tus kheej cov khoom ntawm cov nucleotides thiab muaj peev xwm hloov pauv hauv lawv.
Levels of organization of hereditary information
Muaj 3 theem ntawm lub koom haum: noob, chromosomal thiab genomic. Tag nrho cov ntaub ntawv xav tau rau kev sib txuas ntawm cov protein tshiab yog muaj nyob rau hauv ib qho me me ntawm cov saw - cov noob. Ntawd yog, cov noob yog suav tias yog qib qis tshaj plaws thiab yooj yim tshaj plaws ntawm cov ntaub ntawv encoding.
Cov noob, dhau los, tau sib sau ua ke rau hauv chromosomes. Ua tsaug rau xws li ib lub koom haum ntawm cov neeg nqa khoom ntawm cov khoom siv los ntawm cov cuab yeej cuab tam, pab pawg ntawm cov cwj pwm hloov pauv raws li qee txoj cai thiab raug xa los ntawm ib tiam mus rau lwm tus. Nws yuav tsum tau muab sau tseg tias muaj ntau incredibly ntau yam noob nyob rau hauv lub cev, tab sis cov ntaub ntawv tsis ploj txawm tias nws yog recombined ntau zaus.
cais ntau hom noob:
- muaj 2 hom raws li lawv lub hom phiaj ua haujlwm: cov qauv thiab kev tswj hwm;
- los ntawm kev cuam tshuam ntawm cov txheej txheem tshwm sim hauv lub cell, muaj: supervital, lethal, conditionally lethal genes, as well as mutator genesthiab antimutators.
Cov noob nyob rau hauv cov chromosome nyob rau hauv ib qho kev txiav txim linear. Nyob rau hauv chromosomes, cov ntaub ntawv tsis yog random tsom, muaj ib qho kev txiav txim. Muaj txawm tias daim ntawv qhia qhia txoj haujlwm, lossis gene loci. Piv txwv li, nws paub tias cov ntaub ntawv ntawm cov xim ntawm lub qhov muag ntawm tus me nyuam yog encrypted nyob rau hauv chromosome tooj 18.
Dab tsi yog genome? Qhov no yog lub npe ntawm tag nrho cov nucleotide sequences nyob rau hauv lub cell ntawm lub cev. Lub genome characterizes tag nrho cov hom, tsis yog ib tug tib neeg.
Yim noob neej txoj cai yog dab tsi?
Qhov tseeb yog tias tag nrho cov peev txheej loj ntawm tib neeg txoj kev loj hlob tau muab tso rau hauv lub sijhawm ntawm kev xav. Tag nrho cov ntaub ntawv keeb kwm uas tsim nyog rau kev loj hlob ntawm zygote thiab kev loj hlob ntawm tus me nyuam tom qab yug me nyuam yog encrypted nyob rau hauv cov noob. Tshooj ntawm DNA yog cov khoom siv tseem ceeb tshaj plaws ntawm cov ntaub ntawv keeb kwm yav dhau los.
Ib tug tib neeg muaj 46 chromosomes, los yog 22 somatic khub ntxiv rau ib qho chromosome txiav txim poj niam txiv neej los ntawm txhua tus niam txiv. Qhov no diploid txheej ntawm chromosomes encodes tag nrho lub cev tsos ntawm ib tug neeg, nws lub hlwb thiab lub cev muaj peev xwm thiab predisposition rau cov kab mob. Somatic chromosomes yog outwardly indistinguishable, tab sis lawv nqa cov ntaub ntawv sib txawv, vim ib tug ntawm lawv yog los ntawm leej txiv, lwm tus yog los ntawm leej niam.
Tus txiv neej txoj cai txawv ntawm tus poj niam los ntawm khub kawg ntawm chromosomes - XY. Cov poj niam diploid teeb yog khub kawg, XX. Cov txiv neej tau txais ib qho X chromosome los ntawm lawv niam yug, thiab tom qab ntawd nws kis mus rau lawv cov ntxhais. Kev sib deev Y chromosome raug xa mus rau cov tub.
Tib neeg chromosomes hosib txawv ntawm qhov loj. Piv txwv li, khub me me ntawm chromosomes yog 17. Thiab khub loj tshaj yog 1 thiab 3.
Txoj kab uas hla ntawm tib neeg ob lub helix tsuas yog 2 nm. Lub DNA yog nruj heev uas nws haum rau hauv lub me me ntawm lub cell, txawm hais tias nws yuav ntev txog 2 meters yog tias tsis muaj mob. Qhov ntev ntawm lub helix yog ntau pua lab tus nucleotides.
Tus kab mob caj ces kis li cas?
Yog li, lub luag haujlwm dab tsi ua DNA molecules ua si hauv lub cell thaum faib? Genes - cov ntaub ntawv keeb kwm yav dhau - nyob hauv txhua lub cell ntawm lub cev. Txhawm rau kom dhau lawv cov cai rau tus ntxhais kab mob, ntau tus tsiaj faib lawv cov DNA rau hauv 2 qhov chaw zoo tib yam. Qhov no hu ua replication. Nyob rau hauv tus txheej txheem ntawm replication, DNA unwinds thiab tshwj xeeb "tshuab" ua tiav txhua sawb. Tom qab genetic helix bifurcates, lub nucleus thiab tag nrho cov organelles pib faib, thiab ces tag nrho cell.
Tab sis ib tug neeg muaj cov txheej txheem sib txawv ntawm cov noob hloov pauv - kev sib deev. Cov cim qhia ntawm leej txiv thiab leej niam sib xyaw, cov kab mob caj ces tshiab muaj cov ntaub ntawv los ntawm ob niam txiv.
Kev khaws cia thiab xa tawm cov ntaub ntawv keeb kwm yav dhau los tau vim yog lub koom haum nyuaj ntawm DNA helix. Tom qab tag nrho, raws li peb hais, cov qauv ntawm cov proteins yog encrypted nyob rau hauv cov noob. Ib zaug tsim thaum lub sij hawm conception, cov cai no yuav luam nws tus kheej thoob plaws hauv lub neej. Lub karyotype (tus kheej txheej ntawm chromosomes) tsis hloov thaum lub sijhawm rov ua dua tshiab ntawm lub cev. Kev sib kis ntawm cov ntaub ntawv yog nqa tawm nrog kev pab ntawm kev sib deev gametes - txiv neej thiab poj niam.
Tsuas yog cov kab mob uas muaj ib txoj hlua ntawm RNA tsis tuaj yeem xa lawv cov ntaub ntawv mus rau lawv cov xeeb ntxwv. Yog li ntawd, nyob rau hauv thiaj li yuavkom rov tsim dua, lawv xav tau tib neeg lossis tsiaj hlwb.
Kev siv cov ntaub ntawv keeb kwm yav dhau los
Nyob hauv lub cell nucleus, cov txheej txheem tseem ceeb tau tshwm sim tas li. Txhua cov ntaub ntawv sau tseg hauv chromosomes yog siv los tsim cov proteins los ntawm cov amino acids. Tab sis DNA strand yeej tsis tawm hauv lub nucleus, yog li lwm qhov tseem ceeb, RNA, xav tau ntawm no. Tsuas yog RNA tuaj yeem nkag mus rau hauv daim nyias nyias thiab cuam tshuam nrog DNA saw.
Los ntawm kev sib cuam tshuam ntawm DNA thiab 3 hom RNA, tag nrho cov ntaub ntawv encoded tau paub. Nyob rau theem twg yog qhov kev siv ntawm cov ntaub ntawv keeb kwm yav dhau? Txhua qhov kev sib cuam tshuam tshwm sim ntawm qib nucleotide. Neeg xa xov liaison RNA luam ib ntu ntawm DNA saw thiab nqa daim ntawv no mus rau ribosome. Ntawm no pib lub synthesis ntawm ib tug tshiab molecule los ntawm cov nucleotides.
Yuav kom mRNA luam qhov tsim nyog ntawm cov saw hlau, lub helix nthuav tawm, thiab tom qab ntawd, thaum ua tiav cov txheej txheem recoding, rov qab los dua. Ntxiv mus, cov txheej txheem no tuaj yeem tshwm sim ib txhij ntawm 2 sab ntawm 1 chromosome.
Txoj cai ntawm kev sib koom ua ke
DNA helices muaj 4 nucleotides - cov no yog adenine (A), guanine (G), cytosine (C), thymine (T). Lawv txuas nrog hydrogen bonds raws li txoj cai ntawm complementarity. Cov hauj lwm ntawm E. Chargaff tau pab tsim txoj cai no, txij li thaum tus kws tshawb fawb pom qee cov qauv ntawm tus cwj pwm ntawm cov tshuaj no. E. Chargaff tau tshawb pom tias molar piv ntawm adenine rau thymine yog sib npaug rau ib qho. Ib yam li ntawd, qhov piv ntawm guanine rau cytosine yog ib txwm ib.
Raws li nws txoj haujlwm, cov kws kho caj ces tau tsim txoj cai ntawm kev sib cuam tshuamnucleotides. Txoj cai ntawm complementarity hais tias adenine ua ke tsuas yog nrog thymine, thiab guanine nrog cytosine. Thaum lub sij hawm decoding ntawm lub helix thiab synthesis ntawm ib tug tshiab protein nyob rau hauv lub ribosome, qhov kev hloov txoj cai no yuav pab kom sai sai nrhiav tau tus tsim nyog amino acid uas txuas mus rau lub hloov RNA.
RNA thiab nws hom
Cov ntaub ntawv keeb kwm yog dab tsi? Qhov no yog qhov sib lawv liag ntawm nucleotides hauv ob txoj hlua ntawm DNA. RNA yog dab tsi? Nws txoj hauj lwm yog dab tsi? RNA, los yog ribonucleic acid, pab tshem tawm cov ntaub ntawv los ntawm DNA, txiav txim siab nws thiab, raws li lub hauv paus ntsiab lus ntawm complementarity, tsim cov proteins tsim nyog rau cov hlwb.
Hauv tag nrho, 3 hom RNA raug cais tawm. Txhua tus ua haujlwm nruj me ntsis.
- Cov ntaub ntawv (mRNA), lossis lwm yam nws hu ua matrix. Nws nkag mus rau hauv nruab nrab ntawm lub cell, mus rau hauv lub nucleus. Nws pom nyob rau hauv ib qho ntawm cov chromosomes cov khoom siv caj ces tsim nyog rau kev tsim cov protein thiab luam ib qho ntawm ob sab ntawm ob txoj saw. Kev luam tawm rov tshwm sim raws li lub hauv paus ntsiab lus ntawm complementarity.
- Kev thauj mus los yog ib qho me me uas muaj cov nucleotide decoders ntawm ib sab, thiab sab nraud sib raug rau lub ntsiab amino acid code. Lub luag haujlwm ntawm tRNA yog xa nws mus rau "rhiav", uas yog, mus rau ribosome, qhov chaw uas nws synthesizes cov amino acid tsim nyog.
- rRNA yog ribosomal. Nws tswj tus nqi ntawm cov protein uas tsim tawm. Muaj 2 qhov chaw - amino acid thiab peptide site.
Qhov txawv tsuas yog thaum txiav txim siab yog tias RNA tsis muaj thymine. Es tsis txhob thymine, uracil muaj nyob ntawm no. Tab sis tom qab ntawd, nyob rau hauv cov txheej txheem ntawm cov protein synthesis, nrog tRNA nws tseem yog lawmteev tag nrho cov amino acids. Yog tias muaj qhov ua tsis tiav hauv kev txiav txim siab ntawm cov ntaub ntawv, ces kev hloov pauv tshwm sim.
Kho cov DNA molecule puas
Tus txheej txheem ntawm kev kho cov saw hlau puas yog hu ua kev kho. Thaum lub sijhawm kho, cov noob puas raug tshem tawm.
Tom qab ntawd qhov yuav tsum tau ua ntawm cov ntsiab lus yog rov ua dua raws nraim thiab sib tsoo rov qab rau hauv tib qhov chaw ntawm cov saw hlau los ntawm qhov uas nws tau muab rho tawm. Txhua yam no tshwm sim ua tsaug rau cov tshuaj tshwj xeeb - enzymes.
Vim li cas kev hloov pauv tshwm sim?
Vim li cas qee cov noob pib hloov pauv thiab tsis ua lawv txoj haujlwm - kev khaws cov ntaub ntawv tseem ceeb ntawm cov noob caj noob ces? Qhov no yog vim qhov yuam kev decoding. Piv txwv li, yog tias adenine raug hloov pauv nrog thymine.
Muaj kuj muaj chromosomal thiab genomic mutations. Kev hloov pauv ntawm chromosomal tshwm sim thaum daim ntawv ntawm cov ntaub ntawv keeb kwm poob tawm, raug muab luam tawm, lossis txawm tias hloov mus rau lwm qhov chromosome.
Genomic mutations yog qhov loj tshaj plaws. Lawv qhov laj thawj yog qhov hloov pauv ntawm cov chromosomes. Ntawd yog, thaum tsis yog ib khub - lub teeb diploid, lub teeb triploid muaj nyob hauv karyotype.
Tus piv txwv nto moo tshaj plaws ntawm kev hloov pauv triploid yog Down syndrome, uas tus kheej ntawm chromosomes yog 47. Hauv cov menyuam yaus, 3 chromosomes raug tsim los ntawm 21 khub.
Kuj paub tias yog kev hloov pauv li polyploidy. Tab sis polyplodiapom tsuas yog hauv cov nroj tsuag xwb.
