Ho ikatisa ha DNA
Ho pheta-pheta ha DNA ke ts'ebetso ea motheo ea baeloji e lumellang lisele ho pheta-pheta lintho tsa tsona tsa lefutso pele ho karohano ea sele, e le hore sele e 'ngoe le e 'ngoe ea morali e fumane kopi e tšoanang ea DNA. Ts'ebetso ena ke motheo oa lefa la liphatsa tsa lefutso 'me e phetha karolo ea bohlokoa kholong, tokisong le tlhokomelong ea lintho tse phelang. Ho utloisisa mokhoa oa ho pheta-pheta ha DNA ha ho bohlokoa feela baelojing ea motheo empa hape ho na le litlamorao tse pharaletseng masimong a kang liphatsa tsa lefutso, bongaka le baeloji.
Sebopeho sa DNA le Bohlokoa ba ho Ikatisa
DNA, kapa deoxyribonucleic acid, ke molek'hule e bolokang tlhahisoleseding ea liphatsa tsa lefutso ka liseleng. DNA e na le likhoele tse peli tsa polynucleotide tse etsang helix e habeli. Nucleotide ka 'ngoe e na le sehlopha sa phosphate, tsoekere ea deoxyribose, le e 'ngoe ea metheo e mene ea naetrojene: adenine (A), guanine (G), cytosine (C), le thymine (T). Metheo ena e kopana ka ho khetheha (A le T, le G le C) ka libonto tsa haeterojene, e leng se etsang "li-rung" tsa helix e habeli ea DNA.
Ho ikatisa ha DNA ho lokela ho etsahala ka ho nepahala ho hoholo hobane diphoso di ka lebisa diphetohong tse kotsi. Ho feta moo, ho ikatisa ho sebetsang hantle ho netefatsa hore disele tse sa tswa thehwa di ka sebetsa hantle, ho boloka botsitso ba lefutso ba mmele.
Mehato ea ho Ikatisa ha DNA
Ho ikatisa ha DNA ho etsahala ka letoto la mehato e hokahaneng haholo, e kenyeletsang lienzyme le liprotheine tse 'maloa tse ikhethileng.
1. Letšolo
Mokhoa oa ho ikatisa ha DNA o qala sebakeng se itseng ka har'a molek'hule ea DNA e bitsoang "tšimoloho ea ho ikatisa" (ori). Libaktheria, hangata ho na le ori e le 'ngoe, ha ho le joalo ho li-eukaryote, ho na le li-ori tse ngata ho potlakisa mokhoa oa ho ikatisa. Enzyme ea helicase e qala mokhoa ona ka ho lokolla helix e habeli, e arola likhoele tse peli tsa DNA le ho etsa sebopeho se tsejoang e le "fereko ea ho ikatisa."
Nakong ena, liprotheine tse tlamang khoele e le 'ngoe (SSB) li tsitsisa likhoele tsa DNA tse arohaneng e le hore li se ke tsa kopana hape. Ka mor'a moo, enzyme ea primase e kopanya primer e khutšoanyane ea RNA e fanang ka sebaka sa ho qala bakeng sa DNA polymerase ho qala ho kopanya khoele e ncha ea DNA.
2. Ho lelefatsa
Hang ha primer e se e kentsoe, enzyme ea DNA polymerase e qala ho kopanya khoele e ncha ea DNA ka ho eketsa li-nucleotide khoeleng e ntseng e hola, ho latela li-base pair tse itseng. DNA polymerase e ka atolosa khoele feela ka lehlakoreng la 5′ ho isa ho 3′. Ka hona, khoele e le 'ngoe, e bitsoang khoele e etellang pele, e etsoa ka mokhoa o tsoelang pele ho latela tataiso ea fereko ea ho pheta-pheta.
Ka lehlakoreng le leng, khoele e fapaneng, e bitsoang khoele e salang morao, e kopanngoa ka mokhoa o sa khaotseng e le letoto la likotoana tse khutšoanyane tse bitsoang likotoana tsa Okazaki. Karolo e 'ngoe le e 'ngoe ea Okazaki e qala ka primer ea RNA 'me hamorao e kopanngoa hammoho ho etsa khoele e le 'ngoe e tsoelang pele.
3. Pheliso
Qetellong ea ho ikatisa, primer ea RNA e tlosoa 'me e nkeloa sebaka ke DNA ke DNA polymerase. Ka mor'a moo, enzyme ligase e kopanya likaroloana tsa Okazaki holim'a khoele e setseng, e hlahisang khoele ea DNA e tsoelang pele, e sa senyehang.
Lipheding tsa eukaryotic, libaka tse khethehileng lipheletsong tsa li-chromosome tse bitsoang li-telomere le tsona lia phetoa. Li-telomere li thusa ho thibela tahlehelo ea tlhahisoleseling ea bohlokoa ea liphatsa tsa lefutso nakong ea ho ikatisa, 'me enzyme telomerase e bapala karolo ea bohlokoa ho bolokeng bolelele ba telomere.
Li-enzyme le Liprotheine li Bohlokoa ho Pheta-phetong ea DNA
Li-enzyme le liprotheine tse fapaneng li phetha karolo ea bohlokoa ho ikatiseng ha DNA ka katleho. Tse ling tsa tsona ke tsena:
1. Helicase: E bula khoele e habeli ea DNA ka ho roba litlamo tsa haeterojene pakeng tsa lipara tsa motheo, e leng se etsang fereko ea ho ikatisa.
2. Primase: E kopanya li-primase tse khutšoane tsa RNA tse fanang ka sebaka sa ho qala bakeng sa polymerase ea DNA.
3. DNA Polymerase: E eketsa di-nucleotide qetellong ya primer kapa khoele e ntseng e hola, e leng se etsang khoele e ntjha ya DNA.
4. DNA Ligase: E hokahanya likaroloana tse arohaneng tsa DNA, haholo-holo ha e kopanya likaroloana tsa Okazaki khoeleng e salang morao.
5. Protheine e Tlamang ea Khoele e le 'Ngoe (SSB): E tsitsisa likhoele tsa DNA tse bulehileng e le hore li se ke tsa kopana hape.
6. Topoisomerase: E thibela ho kobeha ho feteletseng ho DNA ka ho roba karolo e le 'ngoe kapa tse peli tsa DNA ho lokolla tsitsipano, ebe e li kopanya hape.
7. Telomerase: E lelefatsa li-telomere lipheletsong tsa li-chromosome ho li-eukaryote, e leng ea bohlokoa bakeng sa ho rarolla bothata ba ho ikatisa ha li-chromosome qetellong.
Ho nepahala le ho Lokisa Liphoso
Ho pheta-pheta ha DNA ka nepo ke senotlolo sa ho boloka botsitso ba liphatsa tsa lefutso. Polymerase ea DNA e na le bokhoni ba ho lokisa bo tsejoang e le ho hlahloba liphoso. Haeba DNA polymerase e kenya nucleotide e fosahetseng, e ka lemoha ho se lumellane hona, ea khaola karolo e fosahetseng, 'me ea e nkela sebaka ka nucleotide e nepahetseng.
Ho phaella moo, ho na le mekgwa ya ho lokisa ka mora ho kopitsa e sebetsanang le diphoso tse sa balweng hantle. Tsena di kenyeletsa tokiso e sa tsamaellaneng, e lemohang le ho lokisa metheo e senyehileng.
Litšebeliso le Litlamorao tsa ho Ikatisa ha DNA
Ho utloisisa ho ikatisa ha DNA ho na le lits'ebetso tse ngata tsa bohlokoa. Theknolojing ea baeloji, mokhoa oa Polymerase Chain Reaction (PCR) o sebelisa melao-motheo ea ho ikatisa ha DNA ho matlafatsa likaroloana tse itseng tsa DNA ka har'a vitro. Mokhoa ona o bohlokoa lipatlisisong tsa liphatsa tsa lefutso, forensics, tlhahlobo ea mafu le tse ling.
Bongaka, ho se sebetse hantle ha ho ikatisa ha DNA ho ka lebisa mafung a fapaneng a liphatsa tsa lefutso le kankere. Ho hlahisa meriana e mecha e shebaneng le li-enzyme tse itseng tsa ho ikatisa liseleng tsa kankere ke sebaka sa lipatlisiso tse matla.
Qetello
Ho pheta-pheta ha DNA ke ts'ebetso ea bohlokoa e netefatsang hore sele e 'ngoe le e 'ngoe e ncha e fumana kopi e nepahetseng le e felletseng ea DNA ea eona. Ho nepahala le katleho ea ho pheta-pheta ha DNA ho bolokoa ke tšebelisano-'moho e hlokolosi ea li-enzyme le liprotheine tse ngata. Ka kutloisiso e tebileng ea ho pheta-pheta ha DNA, re ka tsoela pele ho atolosa tsebo ea rona ea liphatsa tsa lefutso, ra ntlafatsa mekhoa ea theknoloji ea baeloji, le ho nts'etsapele mekhoa ea bongaka e sebetsang haholoanyane. E le e 'ngoe ea lits'ebetso tsa bohlokoa ka ho fetisisa tsa baeloji, ho pheta-pheta ha DNA ho ntse ho le setsi sa lipatlisiso tse ntseng li hola tsa saense.
