Nucleotide - Iyini? Ukwakheka, isakhiwo, inombolo kanye ukulandelana nucleotide esikuziphathimandla DNA

Kukho konke ukuphila emhlabeni yakhiwa amaseli amaningi ukuthi ukusekela ukuhleleka kuka yenhlangano zabo ngezithukuthuku eziqukethwe kuyi-nucleus ye ulwazi zofuzo. Kuyinto isekhona, ukusebenza futhi adluliselwa compounds eziyinkimbinkimbi macromolecular - a nucleic acid ehlanganisa amayunithi monomer - ama-nucleotide. akunakwenzeka overestimate indima acid nucleic. Ukuzinza izakhiwo zabo kunqunywa ukusebenza evamile umzimba, futhi noma iyiphi ngeziphambeko isakhiwo nakanjani kuyoholela izinguquko enhlanganweni yeselula, umsebenzi izinqubo bokuphila ukusebenza lamaseli jikelele.

Umqondo nucleotide futhi izakhiwo zalo

Ngamunye molecule ye-DNA noma RNA yakhiwa ezincane compounds monomeric - nucleotide. Ngamanye amazwi, lo-nucleotide - amabhlogo wokwakha of acid nucleic, co-enzyme nezinye izingxube zamakhemikhali eziningi eziphilayo, okuyizinto ezibalulekile iseli phakathi nokuphila kwalo.

I izakhiwo eziyinhloko yalezi izinto ezibalulekile zibandakanya:

• ukugcinwa kolwazi mayelana isakhiwo amaprotheni nokhondolo njengefa;
• Ukulawula ukukhula kanye nokubeletha;
• iqhaza umzimba kanye nezinye izinqubo eziningi bokuphila kuseli.

Ukwakheka nucleotide

Ekhuluma nucleotide, asikwazi ukugxila inkinga ebalulekile enjengesifundo isakhiwo sabo kanye nokwakheka.

nucleotide ngasinye siqukethe:

• zinsalela ushukela;
• base-nitrogen;
• phosphate iqembu noma ezisalayo of wali band acid.

Singasho ukuthi nucleotide - ekhuthaza eziyinkimbinkimbi organic. Kuye Ukwakheka ethize kanye nohlobo elisekela nitrogen ku nucleotide pentose nucleic acid isakhiwo selihlukene laba:

• deoxyribonucleic acid noma DNA;
• ribonucleic acid, noma i-RNA.

Ukwakheka nucleic acid

I nucleic ushukela acid-pentose uvezwa. Lokhu ushukela ezinhlanu-carbon ku-DNA ibizwa ngokuthi deoxyribose, e-RNA - ribose. Ingqamuzana ngalinye has pentoses ama-athomu ezinhlanu carbon, ezine zazo kanye athomu-mpilo akha indandatho emihlanu membered, futhi ingxenye yesihlanu iqembu HO-CH2.

Isikhundla athomu ngalinye carbon e-molecule pentose ezikhonjiswe inani Arabhu nge prime (1c, 2C ', 3C, 4C', 5c '). Njengoba zonke izinqubo ukufunda ulwazi zofuzo nge nucleic acid molecule abe directivity esiqinile, ye-athomu ye-carbon futhi ilungiselelo yabo iringi ukukhonza njengephayona pointer esiqondisweni lesifanele.

Iqembu hydroxyl lesithathu nelesihlanu ama-athomu carbon (futhi '5S' bo-3) enamathiselwe wali band acid ezisalayo. Uyena onqumayo ukuthi ubani chemical of DNA ne-RNA eqenjini acid.

Eyokuqala i-carbon-athomu (1S ') base-nitrogen enamathiselwe engqamuzaneni ushukela.

Lesitshalo Ukwakheka nitrogen lezisekelo

Nucleotide ye-DNA ye-nitrogen elisekela amelwa zinhlobo ezine:

• i-adenine (A);
• i-guanine ne (G);
• cytosine (C);
• thymine (T).

Okokuqala okubili basonta ekilasini purines, emibili eyedlule - pyrimidine. Yamamolekhula isisindo purine pyrimidine uhlale esinzima ngokwengeziwe.

Nucleotide RNA lezisekelo nitrogen amelelwe:

• i-adenine (A);
• i-guanine ne (G);
• cytosine (C);
• uracil (U).

Uracil kanye ne-thymine, i-base pyrimidine.

Esikhathini ezincwadini zesayensi futhi ngokuvamile ukuthola amanye isiqu nitrogen elisekela - zesi-Latin (A, T, C, G, U).

imininingwane Greater isakhiwo amakhemikhali purines futhi pyrimidines.

Pyrimidines, okungukuthi, cytosine, i-thymine futhi uracil, e isakhiwo emelelwa athomu nitrogen ezimbili futhi ama-athomu amane carbon likhula lakha isiyingi eziyisithupha membered. Kuyiatom inenombolo ayo kusuka 1 kuya 6.

Purines (i-adenine futhi guanine) siqukethe pyrimidine futhi imidazole noma heterocycles ezimbili. Mpilo purine lezisekelo emelelwa ama-athomu nitrogen ezine futhi ama-athomu ezinhlanu carbon. athomu ngalinye ibalwa kusukela ku-1 kuya 9.

Egcekeni umphumela base-nitrogen kanye ezisalayo pentose kwakhiwa nucleoside. Nucleotide - ekhuthaza nucleoside futhi iqembu phosphate.

Ukwakheka phosphodiester izibopho

Kubalulekile ukuqonda umbuzo kanjani ukuze uhlanganise ama-nucleotide esikuziphathimandla polypeptide ukwakha nucleic acid-molecule. Lokhu kwenzeka ngenxa okuthiwa phosphodiester izibopho.

Ukuxhumana ka-nucleotide okubili yenza dinucleotide. Kumiswa compounds esisha senzeka ngo ukufingqa phakathi okuseleyo phosphate elilodwa monomer nomunye hydroxy pentose phosphodiester isibopho kwenzeka.

Polynucleotide zamagama - okuphindaphindiwe ukuphindaphinda okunjena (izikhathi eziyizigidi ezimbalwa). A polynucleotide uchungechunge yakhiwa ngokwakha phosphodiester izibopho phakathi nekhulu lesithathu nelesihlanu carbons ushukela (bo-3 'futhi 5S').

Ukubuthanela polynucleotide - inqubo eyinkimbinkimbi senzeka lapho enzyme-DNA polymerase, esinikela kuphela ukukhula uchungechunge ekucineni (3) nge khulula iqembu hydroxy.

Isakhiwo molecule ye-DNA

A molecule ye-DNA kanye amaprotheni kungaba isakhiwo lokuqala, lesibili futhi ephakeme.

Kulandzelana kwalokucuketfwe lokuhleliwe nucleotide esikuziphathimandla DNA ichaza zalo eziyinhloko isakhiwo. isakhiwo sesibili Kumiswa ngenxa hydrogen izibopho, ngesisekelo okuyinto okuvela wabeka complementarity isimiso. Ngamanye amazwi, e synthesis DNA Helix double izenzo njalo ezithile: i-adenine, ne-thymine uhambelana kombonisi wesifunda nezinye, i-guanine ne - cytosine, noHezekeli. Kuzo adenine ihambisane ne-thymine noma i-guanine ne-cytosine akhiwa ezimbili zokuqala futhi in the sakamuva icala ezintathu hydrogen izibopho. ekhuthaza enjalo inikeza okuqinile isibopho nucleotide ngamaketanga futhi ibanga elilinganayo phakathi kwabo.

Ukwazi ukulandelana nucleotide e neketanga DNA nge isimiso complementarity lungaboniswa wesibili noma zinsiza mzimba.

Kumiswa isakhiwo ephakeme eyinkimbinkimbi DNA ngezibopho ngakuthathu, okuyinto molecule okwenza kube emfishane futhi abakwaziyo ibekwe endaweni ivolumu iseli encane. Ngokwesibonelo, E. coli obuphelele DNA mkhulu kunezinhliziyo 1 mm, kuyilapho ubude iseli - engaphansi kuka 5 microns.

Isibalo ama-nucleotide ku-DNA, futhi ubuhlobo bawo ambalwa kungaphansi umthetho Chergaffa (inombolo purine elisekela zihlale ilingana nenani pyrimidine). Ibanga phakathi nucleotide - a alinganayo njalo 0,34 NM, nesisindo yamangqamuzana yabo.

Isakhiwo i-molecule ye-RNA

RNA imelelwa polynucleotide chain eyodwa, ezakhiwe covalent izibopho phakathi pentose (ribose kuleli cala) kanye moiety phosphate. Ubude kuba DNA sifushane. Ukwakheka zinhlobo izisekelo nitrogen ku nucleotide futhi kukhona umehluko. I-RNA pyrimidine base-thymine esikhundleni uracil esetshenziswa. Kuye nemisebenzi eyenziwa emzimbeni, i-RNA bungabi izinhlobo ezintathu.

• Ribosomal (rRNA) - ngokuvamile aqukethe kusuka 3,000 kuya nucleotide 5,000. Njengoba isakhi kudingekile kwesakhiwo ehilelekile kumiswa isikhungo esebenzayo ye ribosomes, izindawo omunye izinqubo ezibaluleke kakhulu kuseli - biosynthesis amaprotheni.
• Ezokuthutha (tRNA) - siqukethe isilinganiso 75 - 95 ama-nucleotide, wenza ukudluliswa endaweni ye oyifunayo acid acid polypeptide zamagama e ribosome. Uhlobo ngalunye tRNA (okungenani 40) has esingokwemvelo yayo kuphela ke ekulandelaneni nucleotide noma monomers.
• Ulwazi (RNAi) - e nucleotide Ukwakheka wehlukile kakhulu. Ukudluliswa ukwaziswa kwezakhi zofuzo kusukela DNA ribosomes, uba kuyisibonelo zamagama engqamuzaneni amaprotheni.

Indima nucleotide emzimbeni

Nucleotide kuseli enze eziningi imisebenzi ebalulekile:

• Kusetshenziswa njengoba izitini zokwakha acid nucleic (nucleotide purine futhi pyrimidine uchungechunge);
• zinengxenye izinqubo eziningi umzimba kuseli;
• ingxenye ATP - main umthombo wamandla kumaseli;
• yenza njenge zithwala wokunciphisa okulingana kuseli (nad +, NADP +, mkhuba, FMN);
• yenza njenge bioregulators;
• kungenziwa kubhekwe njengento izithunywa yesibili extracellular zamagama avamile (isib ekamu noma cGMP).

Nucleotide - iyunithi monomer esakha ngaphezulu compounds eziyinkimbinkimbi - acid nucleic, ngaphandle lapho ukudluliselwa ukwaziswa kwezakhi zofuzo, isitoreji yayo kanye nokudlala. nucleotide Mahhala izingxenye eziyinhloko ezihilelekile izinqubo isignali amandla futhi amaseli asekelayo ukusebenza evamile wonke umzimba.