Isakhiwo DNA siqukethe ... amakhemikhali ukwakheka le-DNA

Abantu abaningi baye ngizibuza ukuthi kungani izimpawu ezithile litholakale abazali ukunikeza ingane (isibonelo, umbala wamehlo, izinwele, ubuso ijamo, nabanye). Isayensi iye kungase kutholakale ukuthi isici yokudlulisa imali incike nesidoda okunikelwe, noma i-DNA.

Uyini-DNA?

Okwamanje, ngaphansi deoxyribonucleic acid baqonde kwakwakhe eziyinkimbinkimbi ukuthi unesibopho ukudluliselwa nezakhi zofuzo. Lokhu-molecule atholakala kuwo wonke amangqamuzana omzimba wethu. It zahlelwa izici eziyinhloko umzimba wethu (sokuthuthukiswa trait uhambelana amaprotheni ethize).

Yini-ke aqukethe? Isakhiwo DNA siqukethe compounds eziyinkimbinkimbi - ama-nucleotide. Ngu block ehloselwe nucleotide noma kwakwakhe mini kokuba e oyiyo base-nitrogen, amasalela of wali band acid kanye ushukela (kuleli cala - deoxyribose).

DNA kuyinto double-molecule balahleke, lapho ngamunye izifunda exhunywe kwi ezinye ngokusebenzisa nitrogen izisekelo isimiso complementarity.

Ngaphezu kwalokho, kungaba bazitshela ukuthi kuyi-DNA kuhlanganisa izakhi zofuzo - ethize nucleotide ukulandelanisa obhekene amaprotheni zamagama. Yiziphi izindawo amakhemikhali ukwakheka deoxyribonucleic acid kuba?

nucleotide

Njengoba kushiwo, lisisakhiwo isakhi deoxyribonucleic acid kuyinto nucleotide. Lena ibhizinisi eziyinkimbinkimbi. Ukubunjwa DNA nucleotide elandelayo.

Ophakathi nendawo ezinhlanu-ingxenye nucleotide ushukela (deoxyribose e DNA Ngokungafani RNA, equkethe ribose). Ukuze wona uthela base-nitrogen, okuyinto isehlane 5 izinhlobo: i-adenine, i-guanine ne-thymine, uracil ne-cytosine. Ngaphezu kwalokho, nucleotide ngayinye yakhiwa kanye acid zinsalela wali band.

Isakhiwo DNA siqukethe kuphela labo nucleotide ukuthi unayo wabonisa iyunithi kwesakhiwo.

Zonke nucleotide ahlelwe neketanga bese ulandela nomunye. Ukubuthelela ka ezintathu (ama-nucleotide amathathu), akha ezilandelana ngayo triplet ngasinye sihambisane ethile acid acid. Imiphumela iba yinhlanganisela yokukhandleka chain.

Basebenza ndawonye ngokusebenzisa ukuxhumana nitrogen elisekela. Ubudlelwano eziyisisekelo phakathi nucleotide parallel izifunda - hydrogen.

ukulandelanisa Nucleotide ziyisisekelo zofuzo. Ukwephulwa e isakhiwo sabo, okuholela ukuhluleka esikhathini zamagama amaprotheni nokubonakaliswa yokwanda koshintsho. Isakhiwo DNA siqukethe izakhi zofuzo ezifanayo ukuthi ukucacisa cishe bonke abantu futhi uwahlukanise kusukela ezinye izinto eziphilayo.

ukuguqulwa a nucleotide

Kwezinye izimo, ngenxa ukudluliselwa uzinze we ukuguqulwa imfanelo base-nitrogen isetshenziswa. Ukwakheka kwamakhemikhali-DNA ukulungiswa okunamathiselwe leqembu methyl (CH3). ukuguqulwa okunjalo (owodwa nucleotide) ivumela ekulinganiseni isakhi sofuzo Inkulumo nokudluliselwa izici indodakazi amaseli.

Lokhu "ngcono" we ukwakheka kwama-molecule akuphazamisi inhlangano elisekela nitrogen.

Lokhu ukuguqulwa is ukusetshenziswa kuma-X chromosome inactivation. Ngenxa yalokho, kwakhiwa uBarr umzimba.

Endabeni ka anda ukuhlaziywa carcinogenesis DNA ebonisa ukuthi uchungechunge nucleotide yabekwa methylation ku substrates eziningi. Ezifundweni elibukelayo, ke kwaphawuleka ukuthi umthombo kuguquka ngokuvamile cytosine methylated. Ngokuvamile phakathi isimila demethylation inqubo kusheshe stop, kodwa ngenxa yinkimbinkimbi kwako okunjena akuyona kwenziwe.

isakhiwo DNA

Ngo isakhiwo engqamuzaneni ezimbili zama-molecule. Uhlobo lokuqala - ukulandelana komugqa nucleotide kwakhiwa. ukwakhiwa yabo kungaphansi kwemithetho ethile. Ukuqopha ngesikhathi nucleotide molecule ye-DNA liqala ngala 5'-Terminus futhi 3'-Terminus uphela. I wesifunda wesibili esisogwini Kunalokho, yakhiwa ngendlela efanayo, kuphela molecule ungomunye spatially iqondene lenye, lapho 5'-Terminus eyodwa uchungechunge itholakala maqondana 3'-ekupheleni lesibili.

Helix - DNA isakhiwo yesibili. Ibangelwa khona hydrogen izibopho esukela phakathi nucleotide eziphikisanayo. Isibopho hydrogen Kumiswa (thymine kuphela, i-guanine ne nekuphikisana kungaba isibonelo, malungana Strand adenine ihambisane lokuqala - uracil noma cytosine) phakathi izisekelo aphelele nitrogen. ukunemba okunjalo kungenxa yokuthi ukwakhiwa kwe-circuit sesibili senzeka ngesisekelo owokuqala, ngakho phakathi izisekelo nitrogen khona umdlalo ngqo.

I zamagama engqamuzaneni

Kusho molecule ye-DNA bakheka kanjani?

Ngo umjikelezo we lasungulwa izigaba ezintathu:

• Ukukhipha izifunda.
• Ukubusa Kuhlanganisa amayunithi komunye emaketangeni.
• Isandiso kusukela wesifunda wesibili ngokuvumelana nesimiso of complementarity.

Ngesikhathi sigaba ngokuhlukana zishintshe ubuswa enzyme - DNA gyrase. Lezi enzyme bagxile ukubhujiswa hydrogen isibopho phakathi emaketangeni.

Ngemva kwehlukana amaketanga iza Kuhlanganisa eziyisisekelo enzyme - DNA polymerase. yokunamathela kwayo siyenzeka esayithini 5 '. Okulandelayo, ama-enzyme amabombo le-ekupheleni 3', kanyekanye ukubanjwa nucleotide edingekayo lezisekelo ezifanele nitrogen. Ngemva kokufinyelela ububanzi predetermined (isinqamuli) ekupheleni 3 ', polymerase chain linqamuka umthombo.

Uma kwakhiwa osizayo wesifunda phakathi izisekelo yakha hydrogen izibopho, futhi elibamba elalisanda kumiswa DNA.

Ngingalutholaphi ngale molecule?

Uma lokumba isakhiwo kwamangqamuzana nezicubu, kungabonwa ukuthi DNA zitholakala ngokuyinhloko e le kuyi-nucleus yengqamuzana. Ikhenela unesibopho kumiswa ezingaphansi omusha, amaseli noma ukufaniswa kwabo. Ngakho ukwaziswa kwezakhi zofuzo ukwethula therein lihlukaniswe phakathi amaseli elalisanda kumiswa nombala (ukufaniswa elakhiwe) noma ingxenye (ngokuvamile kumelwe kugujwe into enjalo phakathi meiosis). Ukunqotshwa kwe-Imiphumela engumongo e ukuhlukumeza kwetinhlavu yakhe izicubu ezintsha, okuholela ukuguquka kwezakhi zofuzo.

Ngaphezu kwalokho, uhlobo olukhethekile impahla lezinceku eziqukethwe mitochondria. Bona-DNA uhlukile ukuthi nucleus (mitochondrial deoxyribonucleic acid ine ukuma annular senze neminye imisebenzi eminingana).

Mpilo ngokwayo kungenziwa behlukene iyiphi iseli komzimba (ngoba isifundo swab evame ukusetshenziswa kakhulu kusuka ngaphakathi isihlathi noma igazi). Ayikho zofuzo kuphela epithelium exfoliates futhi egazi ezithile (erythrocyte).

imisebenzi

Ukwakheka molecule ye-DNA inquma ukusebenza ukuthumela idatha yayo umsebenzi ezizukulwaneni ngezizukulwane. Lokhu kungenxa zamagama amaprotheni ezithile eziholela ukubonakaliswa a genotype (yangaphakathi) noma phenotypic (yangaphandle - isibonelo, umbala amehlo noma izinwele) sici.

Yokudlulisa ulwazi Kwenziwa ngokusebenzisa ukuqaliswa zaso zofuzo. Ngesisekelo idatha ngekhodi e isimiso sezakhi zofuzo, kukhona ukuthuthukiswa kolwazi oluthile, ribosomal nokudluliselwa RNA. Ngamunye wabo unesibopho isenzo ethize - isithunywa RNA isetshenziswa synthesize amaprotheni ehilelekile ribosomal amaprotheni molecule inhlangano, futhi yakha amaprotheni ezokuthutha elihambisana.

Noma yimuphi ukwehluleka in operation noma isakhiwo zabo ushintsho kuholela ukuphazamiseka umsebenzi wenziwa, futhi ukubonakala kwezici atypical (ukuguquka kwezakhi zofuzo).

DNA ubuyise ukuhlolwa ukucacisa khona izimpawu ahlobene phakathi kwabantu.

ukuhlolwa zofuzo

Yini manje zingasetshenziswa yinoma ekutadisheni izinhlayiya eziyisisekelo zofuzo?

ukuhlaziywa DNA luyasetshenziswa ukuthola ezicini eziningana noma kube nezinguquko umzimba.

Lolu cwaningo lokuqala ukucacisa khona azalwa naso, izifo ngofuzo. Izifo ezihlala zihlanganisa-Down syndrome, Autism,-Marfan syndrome.

Ukuze ubone ukuthi nokuzwelana DNA kungabuye wafunda. Sekuyisikhathi eside ubaba wengane test kwaba chithi saka eziningi, ngokuyinhloko zomthetho, izinqubo. Lolu cwaningo ebekiwe sokunquma ubuhlobo zofuzo phakathi asizalwanga ngokuphinga. Ngokuvamile lokhu izicelo ukuhlolwa kudlule phezu ifa uma kwenzeka izinkinga neziphathimandla.