Te rāpoi ngota pītauira: te taumata o te whakahaere hanganga

DNA rāpoi ngota - i te wae polynucleotide waetahi e e wha deoxyribonucleotide (dAMF, dGMP, dCMP ko dTMP). Ko te ōwehenga o te raupapa o enei nucleotides ki te DNA o kaiao rerekē e motuhake. Haunga nga turanga nitrogenous matua i roto i te DNA hoki kei atu turanga iti deoxyribonucleotides ki 5-methylcytosine, 5-oksimetiltsitozin, 6-methylaminopurine.

Kia reira ko he taea o te whakamahi i te tikanga o te X-ray mātauranga tioata ki ako macromolecules koiora, me te whiwhi tino X-ray, ko reira taea ki te kitea i roto i te hanganga rāpoi o DNA. hāngai ana tikanga mea i runga i te meka e te kurupae o whakarara X-hihi maiki i runga i te ngota tautau, tioata, hanga he tauira ttara, e te nuinga, tei runga i te taimaha o nga ngota ngota, me o ratou wāhi i roto i te wāhi. I roto i te 40s o te rau tau whakamutunga, te ariā o te hanganga e toru-ahu o te rāpoi ngota pītauira kua hoatu mua. whakamatauria U. Astbury e te waikawa deoxyribonucleic ko te tāpae o superimposed nucleotides flat.

Ko te hanganga tuatahi o te rāpoi ngota pītauira

I raro i te hanganga tuatahi o waikawa karihi, te auraa te he raupapa o nucleotides i roto i te mekameka DNA polynucleotide whakaritenga. E hono ana tahi nucleotides e here phosphodiester e kua hanga e i waenganui i te rōpū OH i te tūnga 5 o tetahi nucleotide me deoxyribose te OH-rōpū i roto i te tūranga 3 o tetahi pentose.

Ko te āhuatanga koiora o te ōwehenga waikawa karihi whakaritea e te kounga, me te haere te raupapa nucleotide o te mekameka polynucleotide.

He motuhake te hanganga nucleotide o DNA i kaiao o rerekē rōpū taxonomic me te whakaritea e te ōwehenga (G + C) / (A + T). i takoto Mā te take pū i te tohu o heterogeneity o te hanganga nucleotide o DNA i kaiao o te take mai rerekē. Ko te kupu, i roto i ngā tipu me ngā kararehe teitei ōwehenga (G + C) / (A + T) rerekē paku me he uara nui ake i 1. hoki microorganisms pū whakarea rerekē whānui - i 0.35 ki te 2.70. Heoi, pūtau somatic roto i o te momo o DNA te hanganga nucleotide taua, ie. E. E nehenehe tatou e te mea e te ihirangi o te GC o turanga o DNA o tetahi momo takirua e ōrite.

e kore e whakatau i o heterogeneity o te hanganga nucleotide o DNA i te tere o te pū e hoatu mōhiohio e pā ana ki ona āhuatanga koiora. Aita i maoro a'e, e tika ana ki te rerekē raupapa nucleotide motuhake i roto i te wahi polynucleotide mekameka. tikanga o tēnei e te mōhiohio iranga whakawaeheretia i roto i ngā rāpoi ngota DNA i roto i te raupapa motuhake o ona wae monomeric.

He rāpoi ngota pītauira ngā raupapa nucleotide tikanga mo te tomokanga me te whakamutunga o ngā tukanga o te ariā o DNA (tukuruatanga) o tuipūmua kōtuitanga (tuhi) kōtuitanga pūmua (translation). He raupapa nucleotide e mahi ki te herea whakahohe motuhake me rāpoi ture inhibitory, me te raupapa nucleotide e kore e kawe tetahi mōhiohio iranga. He Kei te whakarerekētia hoki te mara, e tiaki nga rāpoi ngota i nucleases.

Ko te raruraru o nga raupapa nucleotide o DNA kua kore ano i tino faatiti'aifarohia. Whakatau i o raupapa nucleotide o waikawa karihi he tukanga wa-e kai ana, e whakarato ana te whakamahi o te nuclease tikanga wāhinga rāpoi motuhake i runga i nga whatiwhatinga motuhake. Ki te rā, te raupapa nucleotide oti o nga turanga nitrogenous whakapumautia mo te nuinga o tRNA takenga rerekē.

Te rāpoi ngota pītauira: hanganga tuarua

Kua hangaia Watson me Crick he tauira o te helix rua o te waikawa deoxyribonucleic. E ai ki tenei tauira, entwine nga mekameka polynucleotide rua tetahi ki tetahi, reira hanga he ahua o te helix.

turanga Nitrogenous e tū ratou i roto i te hanganga, me te tapahanga phosphodiester - waho.

Te rāpoi ngota pītauira: hanganga wānanga

Te DNA rārangi i roto i te pūtau e te āhua o te rāpoi ngota elongated, kua tākai reira i roto i te hanganga kiato, me te tango ake 1/5 anake o te rōrahi pūtau. Hei tauira, te DNA o te roa pūira tangata ko 8 cm, ka Kikī kia e hāngai ana ki te pūira ki te roa o te 5 nm. Ko taea taua tāpae e tika ana ki te aroaro o nga hanganga DNA helical. Mai i tenei whai reira e taea te helix DNA rua-paea i roto i te wāhi kia tāpae atu he hanganga tuatoru motuhake - superhelix. conformation Supercoiled o te āhuatanga DNA o te pūira o kaiao teitei. hanganga tuatoru taua ähuareka e kotuari here ki amino toenga waikawa e hanga ake nga pūmua e hanga i te matatini nucleoprotein (pūpūira). Na reira, ko te DNA o ngā pūtau eukaryotic e pā ana ki pūmua te nuinga pūāhua taketake - histones, me te pūmua waikawa me te fosfoproteidami.