DNA monomer. Yuav ua li cas monomers tsim ib tug DNA molecule?

Nucleic acids, nyob rau hauv particular DNA, yog paub zoo nyob rau hauv cov kos duab. Qhov no yog piav los ntawm lub fact tias lawv yog cov hlwb tshuaj uas cuam tshuam rau cia thiab kis tau tus mob ntawm nws caj ntaub ntawv. DNA tseem qhib nyob rau hauv 1868, F. Miescher yog ib tug qauv uas muaj muaj zog acidic zog. Zaum tau pom nws los ntawm lub nuclei cov ntshav dawb - tiv thaiv kab mob hlwb. Nyob rau tom ntej no 50 xyoo, txoj kev tshawb ntawm nucleic acids tau ua puav, raws li feem ntau zaum ntseeg biochemists ntsiab organic tshuaj lub luag hauj lwm xws li pub sijhawm, proteins.

Txij li thaum lub seev suab ntawm cov qauv ntawm cov DNA, nqa tawm los ntawm Watson thiab Crick nyob rau hauv 1953, pib ib tug kev tshawb no loj, nws twb pom tawm hais tias, deoxyribonucleic acid - yog ib tug polymer thiab DNA monomers yog nucleotides. Lawv hom thiab lug yuav kawm los ntawm peb nyob rau hauv no ua hauj lwm.

Nucleotides raws li ib tug yam ntxwv tsev kev tshuaj ntsuam genetic ntaub ntawv

Ib tug ntawm cov yam tseem ceeb thaj chaw ntawm nyob teeb meem - yog lub preservation thiab kis tau tus mob ntawm cov ntaub ntawv nyob rau hauv cov qauv thiab cov kev khiav dej num ntawm lub hlwb thiab tag nrho cov kab mob. Qhov no luag hauj lwm yog ua deoxyribonucleic acid thiab DNA monomers - nucleotides sawv cev rau ib yam ntawm cov "tsev blocks" uas los ntawm tus cim tsim thiab ua tshuaj caj. Xav txog dab tsi cov cim coj cov tsiaj qus, tsim supercoil nucleic acid.

Yuav ua li cas rau tsim nucleotides

Yuav kom teb tau lo lus nug no, peb yuav tsum tau ib co kev paub ntawm cov Science News for KIDS ntawm organic tebchaw. Nyob rau hauv kev, peb rov qab hais tias nyob rau hauv cov xwm yog ib pawg ntawm nitrogen-muaj heterocyclic glycosides kev cob cog rua rau monosaccharides - pentoses (ribose los yog deoxyribose). Lawv yog cov hu ua nucleosides. Piv txwv li, adenosine thiab lwm yam nucleosides yog tam sim no nyob rau hauv lub cytosol ntawm lub cell. Lawv hnov mob nrog molecules ntawm lub esterification nrog orthophosphoric acid. Cov khoom ntawm tus txheej txheem no thiab yuav nucleotides. Txhua DNA monomer, thiab muaj cov plaub hom, muaj ib lub npe, rau piv txwv, guanine, thymine thiab cytosine nucleotide.

Purine DNA monomers

Nyob rau hauv biochemistry saws ib tug faib uas cais DNA monomers thiab lawv cov qauv mus rau hauv ob pawg: piv txwv li, purine yog adenine thiab guanine nucleotides. Lawv muaj nyob rau hauv lawv cov muaj pes tsawg leeg purine derivatives - organic tshuaj muaj cov mis C ₅ H ₄ N _4. Monomer DNA - guanine nucleotide, kuj muaj ib tug purine nitrogenous puag kev cob cog rua rau lub deoxyribose N-glycosidic daim ntawv cog lus nyob rau hauv betokonfiguratsii.

pyrimidine nucleotides

Nitrogenous bases, hu ua cytidine thiab thymidine yog pyrimidine derivatives ntawm cov organic teeb meem. Nws mis yog C ₄ H ₄ N _2. Molecule yog ib tug ca rau-membered heterocycle uas muaj ob Nitrogen atoms. Nws yog lub npe hu hais tias es tsis txhob ntawm thymine nucleotides nyob rau hauv lub lwg me me ntawm ribonucleic acid, xws li rRNA, tRNA, mRNA, muaj uracil monomer. Nyob rau hauv tus txheej txheem ntawm transcription, thaum lub sij hawm debiting ntaub ntawv los ntawm cov DNA molecule nyob rau hauv noob mRNA thymine nucleotide yog hloov los ntawm adenine, adenine nucleotide thiab - rau uracil nyob rau hauv mRNA nascent saw. Uas yog kev ncaj ncees yog cov nram qab no nkag: A - Y, T - A.

Chargaff cov kev cai

Nyob rau hauv lub yav dhau los tshooj lus no peb twb yog cov kov li tej ntsiab cai ntawm kev ua raws cai nrog rau cov monomers nyob rau hauv lub DNA chains thiab complex noob mRNA. Renowned biochemist E. Chargaff tsim heev ib tug tshwj xeeb cov khoom teejtug uas lub lwg me me ntawm deoxyribonucleic acid, namely, hais tias tus nqi ntawm adenine nucleotides nyob rau hauv nws yog ib txwm sib npaug zos rau thymine, thiab guanine - cytosine. Lub ntsiab theoretical lub hauv paus ntawm lub hauv paus ntsiab lus Chargaff tau txais kev pab raws li txoj kev tshawb no ntawm Watson thiab Crick, txiav txim uas monomers tsim ib tug DNA molecule, thiab yam uas lawv muaj spatial lub koom haum. Lwm qauv outputted los ntawm Chargaff thiab hu ua complementarity hauv paus ntsiab lus, qhia cov tshuaj sib ze ntawm purine thiab pyrimidine bases thiab lawv muaj peev xwm mus rau lub sib tham nruab nrab ntawm lawv tsim hydrogen bonds. Qhov no txhais tau tias cov kev kho ntawm lub monomers nyob rau hauv ob qho tib si DNA strands nruj me ntsis deterministic Yog li, yam txawv Ib tug thawj strand ntawm DNA yuav tsuas yuav T thiab lwm yam muaj ob tug hydrogen bonds nruab nrab ntawm lawv. Tsuas yog cytosine yuav positioned opposite guanine nucleotide. Nyob rau hauv cov ntaub ntawv no, ntawm nitrogenous bases tsim peb hydrogen bonds.

Lub luag hauj lwm ntawm nucleotides nyob rau hauv lub caj code

Yuav kom siv, cov tshuaj tiv thaiv kev noj qhov chaw nyob rau hauv lub ribosomes ntawm cov protein biosynthesis, muaj yog cov ntaub ntawv hais txog tus neeg txhais lus mechanism ntawm cov amino acid muaj pes tsawg leeg ntawm lub peptide ib theem zuj zus ntawm nucleotides nyob rau hauv lub mRNA ib theem zuj zus ntawm cov amino acids. Nws muab tawm hais tias peb cov uas nyob ib sab monomer nqa cov lus qhia txog ib qho ntawm cov 20 tau amino acids. Qhov no tshwm sim yog hu ua cov tshuaj ntsuam genetic code. Nyob rau hauv qhov kev sib tw ntawm molecular biology uas nws yog siv los mus txiav txim ob qho tag nrho cov peptide amino acid muaj pes tsawg leeg thiab hais rau lo lus nug: uas tsim ib tug DNA molecule monomers, nyob rau hauv lwm yam lus, yog dab tsi nyob tus yeees ntawm cov coj noob. Piv txwv li, lub triplet (codon) AAA nyob rau hauv lub noob encodes cov amino acid phenylalanine nyob rau hauv lub protein molecule, thiab nyob rau hauv lub caj code nws yuav haum triplet UUU nyob rau hauv mRNA saw.

Sis ntawm nucleotides thaum lub sij hawm DNA replication

Raws li yav tas los elucidated, lub structural units ntawm DNA monomers - nws nucleotides. Lawv tej theem zuj zus nyob rau hauv lub circuits yog ib tug qauv rau cov synthesis txheej txheem subsidiary deoxyribonucleic acid molecule. Qhov no tshwm sim tshwm sim nyob rau hauv lub S-theem ntawm interphase hlwb. Lub nucleotide ib theem zuj zus ntawm tshiab DNA molecules nyob rau hauv niam mus chains los ntawm cov enzyme DNA polymerase nrog lub hauv paus ntsiab lus ntawm complementarity (A - C, A - C). Replication hais txog tshua ntawm matrix synthesis. Qhov no txhais tau tias DNA monomers thiab lawv cov qauv nyob rau hauv lub niam txiv saw yog lub hauv paus, uas yog ib tug qauv rau cov ntawv luam ntawm nws cov chaw hauj lwm.

Nws muaj peev xwm hloov cov qauv ntawm cov nucleotide

Los ntawm txoj kev, cia peb hais tias lub deoxyribonucleic acid - yog heev conservative qauv ntawm cov cell nucleus. Muaj yog ib zajlus kom piav: lub caj ntaub ntawv khaws tseg nyob rau hauv lub chromatin ntawm lub nucleus, yuav tsum tau mus ntxiv thiab replicated tsis muaj distortion. Tab sis lub cellular genome yog lossi "nyob rau hauv lub rab phom" ib puag ncig yam tseem ceeb. Piv txwv li, xws txhoj puab heev tshuaj xws li dej cawv, yeeb tshuaj, tej tawg. Tag nrho cov ntawm lawv yog cov thiaj li hu ua mutagens, nyob rau hauv tus ntawm uas tej DNA monomer yuav hloov tau lawv lub tshuaj qauv. Qhov no distortion nyob rau hauv biochemistry yog hu ua ib tug taw tes hloov. Tus zaus ntawm tshwm sim ntawm ib tug txaus siab cell genome. Change yog kho zoo-ua tau hauj lwm cell kho system ua lag luam, xws li ib tug txheej ntawm enzymes.

Ib txhia ntawm lawv, xws li ib tug txwv enzyme, "txiav" lub puas nucleotides, polymerases cia tus synthesis of qub monomers ligase "crosslinked" zoo tu qab tso feem ntawm cov noob. Yog hais tias saum toj no mechanism, rau ib txhia yog vim li cas, lub cell tsis ua hauj lwm thiab puas DNA monomer tseem nyob rau hauv nws cov molecule, lub hloov yog khaws los ntawm kev ntawm matrix synthesis thiab phenotypically manifested nyob rau hauv daim ntawv ntawm cov nqaijrog nrog kho zog, tsis tau ua qhov tsim nyog zog xam qhovkev nyob rau hauv cellular metabolism. Qhov no yog ib tug loj tsis zoo tshaj, txo cell nqi thiab txo lub caij ntawm nws lub neej.