Deoxyribonucleic acid. Model Crick thiab Watson

Tus thawj cov lus qhia txog cov tshuaj thaj chaw ntawm deoxyribonucleic acid yog sau hnub tim 1868 xyoo. Nyob rau hauv lub xyoo pua 20th rau thaum pib ntawm lub forties, nws twb muaj pov thawj hais tias tus qauv yog ib tug linear polymer. Raws li monomer units ua nucleotides uas muaj ib tug nitrogenous puag, ib tug pentose thiab ib tug phosphate pab pawg neeg (ib tug tsib-carbon qab zib).

Deoxyribonucleic acid tej zaum yuav muaj ib lub hauv paus ntawm ob hom: ib tug pyrimidine (thymine (T) thiab cytosine (C)) thiab ib tug purine (adenine (A) thiab guanine (G)). Cov compound yog nqa tawm siv nucleotide phosphodiester daim ntawv cog lus.

Biologists Watson thiab Crick nyob rau hauv 1953 xyoo, noj raws li ib lub hauv paus rau X-ray tsom xam ntawm DNA muaju xaus lus tias cov neeg molecule muaj ib tug khub ntawm lub polymer chains, txoj kev ua ib tug muab ob npaug rau helix. Polynucleotide saw mob rau txhua lwm yam, yog nyob ua ke los ntawm txoj kev ntawm hydrogen bonds uas tsim ntawm complementary (nrog coj) bases nyob rau hauv opposite chains. Thaum no khub tsim tsuas yog raws li nram no: adenine-thymine, guanine-cytosine. Stabilization yog nqa tawm los ntawm ob tug thawj thiab thib ob officers - peb hydrogen bonds.

Lub ob-tso tseg deoxyribonucleic acid muaj ib tug ntev xam raws li tus xov tooj ntawm officers ntawm nrog coj nucleotides (BP). Rau cov neeg molecules, uas muaj xws li ntawm lab thiab phav phav cov niam txiv m.n.p. units noj thiab kb, ntsig txog. Yog li, deoxyribonucleic acid tib neeg chromosome yog sawv cev los ntawm ib tug muab ob npaug rau helix. Nws ntev yog 263 Mb nyob rau hauv

DNA denaturation (melting) yog ib tug txheej txheem uas ib txwm muab ob npaug rau helix linear molecule kis mus rau hauv lub kauj xeev. Thaum melting, muab ob npaug rau-molecule yog muab faib mus rau hauv nyias muaj nyias kev Circuit Court. Qhov kub ntawm uas ib nrab deoxyribonucleic acid melted, ib tug melting point. Nws nyob ntawm qhov zoo ntawm cov molecular muaj pes tsawg leeg.

Raws li twb hais saum toj no, lub G-C officers no stabilized los ntawm peb, thiab ib tug khub ntawm A-T - ob hydrogen bonds. Raws li, qhov ntau dua qhov kev faib ua feem ntawm thawj khub, lub ruaj khov yuav tsum yog tus qauv. Thaum denaturation ntawm ib tug wavelength ntawm 260 nm tsub kom tus haum ntawm lub teeb. Qhov no hyperchromic nyhuv ua nws tau mus muab cov tswj lub molecular lub xeev ntawm cov theem nrab qauv. Yog hais tias cov tshuaj yog maj mam txias molten acid ntawm complementary strands ntawm tsis muaj zog mus yuav yuav tsim dua, tej zaum yuav ua tau ib tug kauv qauv yog zoo tib yam rau cov neeg (thawj). Qhov no muaj peev xwm ntawm DNA rau denaturation thiab renaturation molecules raws li hybridization txoj kev. Nws yog siv nyob rau hauv kev kawm cov qauv ntawm nucleic acids.

Muab ob npaug rau helix molecule, ua tus cab kuj ntawm kev tshuaj ntsuam genetic cov ntaub ntawv, yuav tsum tau raws li ob lub ntsiab uas yuav tsum tau. Firstly, nws yuav tsum tau replicated (dua) uas muaj tseeb, thiab tib ob, rau encode lub synthesis ntawm cov protein molecules. Deoxyribonucleic acid, uas qauv tau piav los ntawm Watson thiab Crick, sau raws nkaus Ii siab rau cov uas yuav tsum tau. Nws yog pom tias nyob rau hauv raws li lub hauv paus ntsiab lus ntawm complementarity, txhua saw nyob rau hauv lub molecule yuav ua tau lub matrix rau tsim ntawm ib tug tshiab thiab ob tog coj Circuit Court. Raws li ib tug tshwm sim, ib theem ntawm replication li tshwm sim khub tus ntxhais molecules muaj ib tug nucleotide ib theem zuj zus tib yam los nyob rau hauv tus thawj DNA molecule. Ntxiv mus, qhov no saw ntxwv noob nyob rau hauv lub encoded protein amino acid ib theem zuj zus teev.

Txij li thaum, raws li tau ua rau pej xeem DNA qhib thiab complementarity hauv paus ntsiab lus, tsim dab uas yog lub luag hauj lwm rau raws roj ntsha los seev suab ntaub ntawv thiab nyob rau hauv cov kev cai ntawm noob synthesis tshuaj. Nyob rau hauv tas li ntawd, cov kev tshawb xav yog tsim thiab cov kev siv molecules.