Cikin jigidar halittar DNA: martabobin tsarin kungiyar

Jigidar halittar DNA - a polynucleotide monomer raka'a wanda suke hudu deoxyribonucleotide (dAMF, dGMP, dCMP da dTMP). A rabo daga cikin jerin wadannan nucleotides a cikin DNA daga daban-daban kwayoyin sun sha banban. Bugu da kari ga babban nitrogenous sansanonin a DNA ne ma wasu deoxyribonucleotides tare da qananan sansanonin: 5-methylcytosine, 5-oksimetiltsitozin, 6-methylaminopurine.

Da zarar akwai yiwuwar ta amfani da hanyar na X-ray crystallography don nazarin nazarin halittu macromolecules kuma samu cikakken X-ray, shi yiwuwa a gano kwayoyin tsarin DNA. Ce hanyar dogara ne a kan gaskiyar cewa a katako na layi daya X-haskoki faru a kan wani crystalline tari kwayoyin halitta, Forms diffraction juna, wanda yafi dogara a kan atomic nauyi na kwayoyin halitta, kuma su location a sarari. A cikin 40s na karshe karni, ka'idar uku-girma tsarin da jigidar halittar DNA da aka sa a gaba. U. Astbury tabbatar da cewa deoxyribonucleic acid ne wani tari na superimposed lebur nucleotides.

A farko tsarin da jigidar halittar DNA

A karkashin farko tsarin da nucleic acid, da ake nufi a jerin nucleotides a polynucleotide tsari DNA sarkar. Nucleotides suna da nasaba tare da wani phosphodiester shaidu cewa an kafa tsakanin OH kungiyar a cikin 5-wuri na deoxyribose na daya nucleotide da OH kungiyar a matsayin 3 na pentose wani.

A nazarin halittu Properties na nucleic acid ayyana ingancin rabo da jerin nucleotides tare da polynucleotide sarkar.

A nucleotide abun da ke ciki na DNA daga kwayoyin na daban-daban taxonomic kungiyoyin ne na musamman da aka ƙaddara da rabo (G + C) / (A + T). Amfani da factor bayani dalla-dalla da aka ƙaddara da mataki na heterogeneity na nucleotide abun da ke ciki na DNA daga kwayoyin na daban-daban asalin. Saboda haka, a cikin mafi girma da shuke-shuke da dabbobi rabo (G + C) / (A + T) dabam dan kadan da kuma yana da darajar fi 1. Domin kwayoyin factor bayani dalla-dalla dabam yadu - daga 0,35 zuwa 2,70. Duk da haka, somatic Kwayoyin na wani nau'in na DNA dauke da wannan nucleotide abun da ke ciki, watau. E. mu iya ce cewa abun ciki na GC nau'i-nau'i daga sansanonin na DNA na daya jinsin su ne m.

Tabbatar da dalilin da heterogeneity na nucleotide abun da ke ciki na DNA a wani kudi na bayani dalla-dalla ba shi ba da bayanai game da nazarin halittu Properties. Kwanan nan, saboda da daban-daban musamman nucleotide jerin a polynucleotide sarkar rabo. Wannan yana nufin cewa kwayoyin bayanai shigar wanda ke aiki a DNA din a wani takamaiman jerin ta monomeric raka'a.

A jigidar halittar DNA hada da nucleotide jerin nufi don qaddamarwa da kuma karewa daga tafiyar matakai na kira na DNA (kwafi) na RNA kira (kwafi) gina jiki kira (translation). Akwai nucleotide jerin cewa bauta wa su ɗaure takamaiman Kunna da kuma hana ruwa guda tsara kwayoyin, kazalika da nucleotide jerin wanda ba kawo wani kayyade bayani. Akwai ma modified da filin, wanda kare kwayoyin daga nucleases.

Matsalar da nucleotide jerin jigidar halittar DNA ba tukuna aka gaba daya warware. Tabbatar da dalilin da nucleotide jeruwar nucleic acid ne lokaci-cinyewa hanya, wanda ya samar da da amfani da nuclease tsakiyan nonon Hanyar takamaiman kwayoyin a raba da wani ɓaɓɓake. A ranar, da cikakken nucleotide jerin nitrogenous sansanonin da aka kafa domin mafi yawan tRNA daban-daban asalin.

Cikin jigidar halittar DNA: sakandare tsarin

Watson da Crick sun tsara wani tsari na biyu Helix na deoxyribonucleic acid. A cewar wannan model, biyu polynucleotide sarƙoƙi entwine juna, game da shi, kafa irin Helix.

Nitrogenous sansanonin suke located cikin tsarin, da kuma wani kashin phosphodiester - a waje.

Cikin jigidar halittar DNA: da manyan tsarin

A mikakke DNA a cikin cell yana da siffar wani elongated DNA, shi ne kunsasshen a wani m tsarin da kuma daukan up kawai 1/5 na cell girma. Alal misali, tsawon mutum chromosome DNA kai 8 cm da kuma cushe a irin wannan hanyar da ya yi daidai a cikin wani chromosome da tsawon 5 nm. Irin wannan stacking ne yiwu ba saboda gaban helical DNA Tsarin. Daga wannan shi ya bi da cewa biyu-stranded DNA Helix a sarari iya zama kara stacking wani takamaiman manyan tsarin - superhelix. Supercoiled conformation na DNA halayyar da chromosomes na mafi girma kwayoyin. Irin manyan tsari ne stabilized da covalent shaidu da amino acid sharan cewa Make Up cikin sunadaran da suka form nucleoprotein hadaddun (chromatin). Saboda haka, DNA daga eukaryotic Kwayoyin da ake dangantawa da sunadaran kagaggun asali hali - histones da acidic sunadaran da fosfoproteidami.