DNA molek'hule: maemo ea mokhatlo oa mehaho

DNA molek'hule - ya diyuniti polynucleotide monomer tseo tse 'nè deoxyribonucleotide (dAMF, dGMP, dCMP le dTMP). The karo-karolelano ea tatelano ya nucleotides tsena ka DNA ea lintho tse fapaneng tse fapaneng ho hang. Ntle ho nitrogenous makalana ka sehloohong DNA boetse e na le tse ling tse makalana nyenyane deoxyribonucleotides le 5-methylcytosine, 5-oksimetiltsitozin, 6-methylaminopurine.

Hang ho ne ho sa monyetla oa ho sebelisa mokhoa oa ho X-ray crystallography ho ithuta macromolecules tsa likokoana-hloko le ho fumana phethahetse X-ray, ho ne ho ka khoneha ho fumana ka ntle ho mohaho o limolek'hule tsa DNA. mokhoa itse e thehiloe e le hantle hore ka khanya ea tšoanang le X-ray etsahetseng ka bonaletsang lesihla liathomo, e bopa e diffraction dipaterone, eo haholo-holo itšetlehile ka boima ba 'mele ea athomo ea liathomo,' me sebaka sa bona ka ho sebaka. Ka 40s ea ho qetela lekholong la lilemo la, khopolo ea ho sebopeho tse tharo-tlhakore tsa DNA molek'hule e se e beha pele. U. Astbury bontšitse hore le asiti deoxyribonucleic ke spongebob tsa superimposed nucleotides bataletse.

Mohaho o ka sehloohong oa ho DNA molek'hule

Tlasa sebopeho sa mathomo ea acid nucleic, e ho ne ho bolela e le tatelano ea nucleotides ka polynucleotide tokisetso ea DNA ketane. Nucleotides li amahanngoa le 'moho ka litlamo phosphodiester tse thehoa pakeng tsa sehlopha OH ka 5 boemo ba nucleotide mong le deoxyribose le OH-sehlopha boemong 3 of pentose e' ngoe.

The thepa tsa likokoana-hloko tsa acid e karo-karolelano nucleic laolwang ke ya boleng le hammoho le nucleotide tatelano ea ketane polynucleotide.

The nucleotide hlophisoa DNA ho tloha tse phelang tsa lihlopha tse fapaneng taxonomic e itseng 'me e laolwang ke karo-karolelano (G + C) / (A + T). Ho sebelisa ntlha e khethehileng o ne a ikemiselitse ka tekanyo e sa heterogeneity tsa nucleotide hlophisoa DNA tloha phelang se hlahang ho yona fapaneng. Kahoo, ka dimela e phahameng le liphoofolo karo-karolelano (G + C) / (A + T) fapana hanyenyane 'me o na le bohlokoa ho feta 1. Ka microorganisms khethehileng coefficient fapana haholo - ho tloha 0,35 ho 2,70. Leha ho le joalo, lisele tse somatic tsa mefuta e meng ea DNA e na le e tšoanang nucleotide sebopeho, ke hore. E. Re ka bolela hore dikahare tsa reba lipara tsa bokatlase ba DNA ea mefuta e 'ngoe ke le tsoanang.

Boikemisetso ba heterogeneity tsa nucleotide hlophisoa DNA ka lebelo la khethehileng ha e fane ka boitsebiso bo mabapi le thepa ea eona likokoana-hloko. Morao tjena, ka lebaka la ho fapaneng nucleotide tatelano itseng ka likarolo polynucleotide ketane. Sena se bolela hore u fumane boitsebiso bo liphatseng tsa lefutso khouthollotsweng ka limolek'hule DNA ka tatelano itseng ya diyuniti lona monomeric.

A DNA molek'hule se se akaretsang nucleotide tatellanong ne a rerile hore le qalo le qetello ea dithulaganyo tsa tswakana tsa DNA (boikatiso) tsa RNA tswakana (mongwalollo) tswakana protheine (phetolelo). Ho na le tatellanong nucleotide tse sebeletsa hore motho a tlame activating e itseng le inhibitory limolek'hule taolo, hammoho le tatellanong nucleotide tse u se ke ua etsa tlhahisoleseding efe kapa efe liphatsa tsa lefutso. Ho boetse ho na tse fetotsoeng tšimong, leo sireletsa limolek'hule ho tloha nucleases.

The bothata ba nucleotide tatellanong ea DNA e-s'o e ho feletseng rarolohile. Boikemisetso ba nucleotide tatellanong ea acid nucleic e ja nako e ngata ka mokhoa o, e leng e fana ka tshebediso ya nuclease bokaholimo ba matsoele mokhoa limolek'hule tse tobileng tsa mangeta a arohaneng. Ho fihlela joale, Bibele e feletseng ea nucleotide tatelano ea makalana ka nitrogenous thehilwe bakeng sa boholo ba tRNA hlahang ho yona fapaneng.

DNA molek'hule: sebopeho se mahareng

Watson le Crick ba qapile mohlala oa Helix habeli ea acid e deoxyribonucleic. Ho ea ka ea mohlala ena, liketane polynucleotide pedi entwine e mong le tse ling tse, kahoo eaba ba etsa e mosa ea Helix.

makalana Nitrogenous ba leng teng ka hare sebopeho, le phosphodiester mokokotlo - ka ntle.

DNA molek'hule: phahameng sebopeho

DNA guttate ka seleng e na le sebōpeho sa e molek'hule o molelele o, e tsa phutheloa ka sebopeho diseke ee le nka ho fihlela 1/5 feela ea bophahamo ba modumo ka seleng. Ka mohlala, DNA ea batho chromosome bolelele ke 8 cm, le tletse e le hore ho tlakoloha ka le chromosome le e-ba bolelele ba 5 NM. stacking joalo ka etsahala ka lebaka la ho ba teng ha mehaho e helical DNA. From ena e latelang hore e habeli-tsielehile DNA Helix ka sebaka ka ho eketsehileng stacking itseng e phahameng sebopeho - superhelix. Supercoiled conformation tsa DNA bath ya chromosomes tsa lintho tse phelang e phahameng. Joalo sebopeho phahameng tsitsisoa ka litlamo covalent ho amino litlhaka kahare asiti tse etsang lihaha-'mele tse theha nucleoprotein rarahaneng (chromatin). Ka lebaka leo, DNA ea lisele eukaryotic amanang le liprotheine haholo tsa motheo tsa tlhaku - histones, hammoho le liprotheine asiti le fosfoproteidami.