Tus qauv ntawm DNA thiab RNA qauv

Yog hais tias peb xav txog tej yam lub tsos ntawm ib tug DNA molecule nws tsa cov kauv, uas yog tsim nyob rau los ntawm ob polynucleotide chains uas yog cov nyob nruab nrab ntawm lawv tus kheej thiab ib txhij nyob ib ncig ntawm ib tug ntawm lawv ntau axes.

Feem ntau, cov DNA qauv yog suav tias yog tsis pub dhau lub tsom xam system, nyob rau raws li lub ntsiab - yog nruj me ntsis taag (rau tej yam kev mob) txoj kev interposition dezoksiribonukleozidmonofosfatov - dNMP, Cheebtsam polynucleotide saw.

Nyob rau hauv uas tsis yog-mutated cell mononucleotides koom phosphodiester bonds, nrog rau lawv tus kheej kaw polynucleotide chains muaj ob qho kev xaiv rau qhov chaw ntawm lub pab pawg neeg ntawm cov 5'-kawg ntawm lub saw yog ib tug phosphate pab pawg neeg, thiab lub OH pab pawg neeg yog nyob rau hauv lub Z'-end Circuit Court.

Yog hais tias peb xav txog ib tug qauv uas muaj ob strands, lub DNA qauv yog xws tias tus polynucleotide saw yuav antiparallel rau txhua lwm yam. Nyob rau hauv no Circuit Court muab khaws cia tseg nyob rau hauv xws li ib tug qauv yuav ua tau vim hydrogen bonds uas muaj nyob nruab nrab ntawm cov bases A-T thiab GC, coplanar, perpendicular mus rau lub ntsiab axis ntawm lub lwg me me kauv. Cov hydrophobic kev sib tshuam, tsim ntawm lub bases ntawm xws li ib tug qauv, muab stability thoob plaws lub ob helix. Rau xws li ib tug qauv, cov qauv ntawm cov DNA yus complementarity ntawm polynucleotide chains, tiam sis tsis lawv yog leejtwg li lawv nucleotide muaj pes tsawg leeg txawv.

Ntxiv mus, xav hais tias yog ib tug DNA qauv, nws yuav tsum tau muab sau tseg hais tias txhua tus neeg molecule yog "ntim" nyob rau hauv ib tug ncaj qha tshwj xeeb, cais chromosome. Cov chromosomes muaj ib tug ntau yam ntawm cov nqaijrog uas sib haum mus rau ib tug ncaj qha txhais ib theem zuj zus ntawm cov DNA molecule qauv. Cov proteins uas txwv kom muab zais rau hauv 2 pawg: histones thiab proteins negistony. Nyob rau hauv lub complex nrog lub nuclear DNA ntawm lub hlwb, cov nqaijrog hu ua chromatin.

Piav txog cov qauv ntawm cov DNA, nws yuav tsum tau muab sau tseg hais tias chromatin muaj tsib hom histones, tag nrho cov zoo xwb uas muab ib tug heev muaj zog daim ntawv cog lus histones nrog DNA. Lub complex ntawm histones thiab DNA molecules txhais feem muab ib tug 146 nucleotide officers, yog reacted, nyob rau hauv uas tsim nucleosomes.

Muaj nyob rau hauv tus qauv ntawm cov DNA molecule cov nqaijrog negistony sawv cev rau ntau yam hom ntxawg cov nqaijrog, txuam nrog rau kev DNA sequences. Tsis tas li ntawd, DNA molecules complementary rau cov qauv ntawm enzymes muab biosynthesis.

Kawm cov qauv ntawm cov DNA thiab RNA nyob rau hauv lub system tsom xam yuav tsum tsuas yog nyob rau hauv lub complex, uas yog, thaum twg yog xav cov qauv ntawm cov DNA, nws yog tsim nyog los xav txog cov qauv thiab cov RNA.

Nws thawj qauv, raws li tau zoo raws li nyob rau hauv cov ntaub ntawv ntawm ib tug DNA qauv yog ib tug algorithm interlace ribonukleozidmonofosfatov, yog li, yuav coj mus rau hauv tus account uas, tsis zoo li DNA, tag nrho cov hom ntawm RNA muaj tsuas yog ib cov saw ntawm lub polynucleotide. Nyob rau hauv cov qauv ntawm cov RNA molecule thiab nws ib strands yog tsim, thiaj hu ua "hairpin" - spiralized loops uas yog AU thiab GC puag thiab stabilized los ntawm hydrogen tsevneeg.

Feem ntau, qhov nruab nrab coob DNA molecule muaj txog 150 nucleotide officers millionov, thiab nws ntev yog plaub centimeters. Lub kuaj tsom ntawm xws molecules yog tsis tshua muaj yooj yim rau txoj kev tshawb no, vim tias thaum nws yog ib lub qee ntawm cov ntaub so ntswg, ib tug qauv nyhav heev fragmented thiab ua me npaum li cas nyob rau hauv loj. Yuav kom tshem tawm no txaav, nyob rau hauv cov kev tshawb fawb cov qauv ntawm cov PCR - kev polymerase chain reaction, nyob rau hauv uas yog xaiv synthesizing ib tug neeg seem ntawm cov DNA molecule, thiab faib cov kev tsim nyog kev tshawb fawb rau nws tawg tsam.