Monomer DNA. Yini monomers akha molecule ye-DNA?

acid nucleic, e-DNA ethize, eyaziwayo ubuciko. Lokhu kuchazwe iqiniso lokuthi kukhona amaseli izinto ezithinta isitoreji futhi ukudluliswa kolwazi zaso zofuzo. DNA namanje evulekile 1868, uF Miescher kuyinto molecule nge izakhiwo eziqinile ane-esidi. Izazi zesayensi ziye zakhomba wakhe kusukela nuclei wamangqamuzana egazi amhlophe - omzimba amaseli. Kuyo yonke le minyaka 50 ezayo, ukutadisha acid nucleic zazenziwa ngezikhathi ezithile, njengoba ososayensi abaningi babekholelwa biochemists main izinto eziphilayo wemfanelo okubandakanya sazuza izici, amaphrotheni.

Kusukela emagama of isakhiwo DNA, eyenziwa Watson Crick ngo-1953, baqala isifundo sina, kwatholakala ukuthi, deoxyribonucleic acid - kuyinto polymer futhi DNA monomers kukhona ama-nucleotide. izinhlobo nezakhiwo zawo atawutadishelwa yithi kulo msebenzi.

Nucleotide njengoba iyunithi isakhi ukwaziswa kwezakhi zofuzo

Omunye izakhiwo eyisisekelo eziphilayo ndaba - kuyinto ukugcinwa ukudluliswa ulwazi isakhiwo nemisebenzi amaseli bese wonke umzimba. Lokhu indima wenziwa deoxyribonucleic acid ne-DNA monomers - nucleotide ukumela uhlobo "amabhlogo wokwakha" kusukela lapho design eliyingqayizivele futhi eyakhelwe izidakamizwa ufuzo. Cabangela lokho izimpawu guided izilwane zasendle, ukudala supercoil nucleic acid.

Kanjani ukwakha ama-nucleotide

Ukuze siphendule lo mbuzo, kudingeka sibe nolwazi oluhle ezinye ukwakheka kwezinto organic compounds. Ikakhulukazi, sikhumbula ukuthi ngokwemvelo kukhona iqembu nitrogen-oqukethe heterocyclic glycosides exhunywe kwi monosaccharides - pentoses (ribose noma deoxyribose). Ziyakwazi ngokuthi nucleosides. Ngokwesibonelo, adenosine nezinye nucleosides bukhona cytosol esitokisini. Indlela abasabela ngayo molecule ye esterification nge orthophosphoric acid. Imikhiqizo yale nqubo futhi ngeke nucleotide. Ngamunye monomer DNA, futhi kukhona zinhlobo ezine, unegama, isibonelo, i-guanine ne-thymine ne-cytosine nucleotide.

monomers purine DNA

Ngo-biochemistry bamukela ngezigaba ehlukanisa monomers DNA nokwakheka kwawo, kwaba ngamaqembu amabili: isibonelo, purine kuyinto adenine ihambisane ne-guanine nucleotide. Ziqukethe ukubunjwa yabo purine nemikhiqizo - izidakamizwa organic kokuba ifomula C ₅ H ₄ N _4. DNA Monomer - nucleotide guanine futhi iqukethe purine base-nitrogen exhunywe kwi-deoxyribose N-glycosidic isibopho ngokutholakala betokonfiguratsii.

pyrimidine nucleotide

lezisekelo nitrogen, ngokuthi cytidine futhi thymidine kukhona okunye pyrimidine of udaba eziphilayo. ifomula Its C ₄ H ₄ N _2. Mpilo kuyinto flat heterocycle ayisithupha membered equkethe athomu amabili-nitrogen. Kuyaziwa ukuthi esikhundleni thymine nucleotide ku molecule ribonucleic acid, ezifana rRNA, tRNA, mRNA, equkethwe monomer uracil. Ngo inqubo umbhalo, ngesikhathi ukudonsa ulwazi kusuka molecule ye-DNA ukukhubazeka kwezakhi ezithile zofuzo mRNA thymine nucleotide esikhundleni i-adenine, i-adenine nucleotide futhi - ukuba uracil e mRNA uchungechunge nascent. Lokho fair is entry elandelayo: A - Y, T - A.

imithetho Chargaff sika

Esikhathini esigabeni sangaphambilini siye kakade ingxenye wathinta phezu izimiso ukuhambisana monomers e amaketanga DNA futhi eziyinkimbinkimbi isakhi sofuzo mRNA. Isazi sokusebenza kwamakhemikhali bodumo E. Chargaff esungulwe impela impahla eyingqayizivele molecule-deoxyribonucleic acid, okungukuthi, inani nucleotide adenine ihambisane kulo njalo ulingana-thymine, futhi i-guanine ne - cytosine. The main isisekelo ezincwadini izimiso Chargaff wakhonza njengephayona ekutadisheni Watson Crick, kunqunywe ukuthi yiziphi monomers akha molecule ye-DNA, futhi lokho abanakho inhlangano ngekwendzawo. Enye iphethini ngokukhishwa ngu Chargaff wabiza complementarity isimiso, kubonisa kokusondelana amakhemikhali purine futhi pyrimidine lezisekelo, ikhono lawo ukusebenzisana phakathi kwabo ukwakha hydrogen izibopho. Lokhu kusho ukuthi ilungiselelo monomers kuzo zombili imicu DNA ngokuqinile deterministic Ngakho, okuphambene A umucu wokuqala DNA kungaba T kanye nezinye hydrogen izibopho kokuba ezimbili phakathi kwazo. cytosine kuphela ingabekwa okuphambene guanine nucleotide. Kulokhu, phakathi izisekelo nitrogen yakha hydrogen izibopho ezintathu.

Indima nucleotide e isimiso sezakhi zofuzo

Ukuqalisa, ukusabela ezazenzeka ribosomes we biosynthesis amaprotheni, kukhona ulwazi mayelana indlela yokuhumusha sokuqanjwa acid acid wokulandelana peptide ka-nucleotide ngekulandzelana mRNA amino acid. Kwatholakala ukuthi monomer ezintathu eduze zinokwaziswa mayelana omunye 20 kungenzeka ama-amino acid. Lesi senzakalo ngokuthi isimiso sezakhi zofuzo. Ekubhekaneni nalezi nselelo we-molecular biology isetshenziswa ukunquma kokubili peptide acid acid ukwakheka kanye ukucacisa mbuzo: akha monomers DNA, ngamanye amagama, ukuthi indlela yokwakheka isakhi sofuzo elihambisana. Ngokwesibonelo, triplet (codon) AAA e isakhi sofuzo buqonda le phenylalanine amino acid engqamuzaneni amaprotheni, futhi isimiso sezakhi zofuzo ngeke silingane triplet UUU e mRNA chain.

Ukuxhumana ka-nucleotide ngesikhathi DNA ukufanisana

Njengoba cacisa ngaphambili, amayunithi isakhi monomers DNA - ke ama-nucleotide. ukulandelana yabo ethize ezifundeni kuyinto isifanekiso ngenqubo zamagama osizayo deoxyribonucleic acid-molecule. Lokhu kwenzeka ngo-S-esiteji of interphase amaseli. Ukulandelana nucleotide ka molecule e-DNA inoveli kwabakhulelwe Kwenzekani ngamaketanga yi polymerase enzyme-DNA ne isimiso of complementarity (A - C, A - C). Ukufanisana libhekisela ukusabela-matrix zamagama. Lokhu kusho ukuthi monomers DNA nokwakheka kwawo esikuziphathimandla umzali ziyisisekelo, okungukuthi kuyisibonelo amakhophi uphiko lwayo.

Ungashintsha isakhiwo se-nucleotide

By the way, ake sithi esidi i-deoxyribonucleic - kuyinto isakhiwo olandelanayo kakhulu kuyi-nucleus yengqamuzana. Kunencazelo enengqondo: ulwazi zofuzo agcinwe chromatin ka-nucleus, kufanele kuqhutshwe futhi ziphindaphindwe ngaphandle ukuhlanekezela. Kodwa ufuzo amaselula wukuthi njalo "ngaphansi isibhamu" yizici zemvelo. Ngokwesibonelo, ezifana amakhemikhali nolaka utshwala, izidakamizwa, emisebeni enemisebe like. Bonke bangabangasokile okuthiwa mutagens, ngaphansi kwethonya okungawela kuso noma yisiphi monomer DNA Ungashintsha yabo isakhiwo sazo sekhemikhali. Lokhu ukuhlanekezela biochemistry ibizwa ngokuthi kuguquka iphuzu. Imvamisa nesenzakalo we sezingeni eliphezulu iseli ufuzo. Ukuguqula izakhi zofuzo uqondiswa kahle ukusebenza uhlelo cell ukulungisa, kuhlanganise iqoqo enzyme.

Ezinye zazo, njenge-enzyme izivimbelo "usike" le-nucleotide ezilimele, polymerases uvumele synthesis monomers evamile ligase "crosslinked" walulama izingxenye isakhi sofuzo. Uma lo mshini ngenhla, ngasizathu simbe, iseli akusebenzi futhi engaphelele DNA monomer uhlala-molecule ayo, le kuguquka is wacosha nge izinqubo-matrix zamagama kanye phenotypically ebonakaliswa ifomu amaprotheni ne izakhiwo ezishintshwe singakwazi ukwenza imisebenzi ezidingekayo esivela umzimba amaselula. Lena isici ongemuhle ekunciphiseni cell ukusebenza kanye nokunciphisa isikhathi ukuphila kwakhe konke.