Monomer na DNA. Wadanne monomers sun kafa kwayar DNA?

Nucleic acid, musamman DNA, sananne ne a cikin art. Wannan ya bayyana ta hanyar gaskiyar cewa su ne abubuwa na tantanin halitta inda ajiya da canzawa na bayanan asirinta ya dogara. DNA, wanda aka gano har zuwa shekara ta 1868 by F. Micher, wani ƙwayar kwayoyi ne tare da furta albarkatun acid. Masanin kimiyya ya gano shi daga kwayoyin leukocytes - sel daga cikin tsarin yaduwar cutar. A cikin shekaru 50 masu zuwa, nazarin nazarin acid na nucleic acid an yi shi ne a wani lokaci, tun da yake yawancin masu binciken halitta sunyi la'akari da muhimman abubuwan da suka shafi kwayoyin halitta, musamman ma, saboda siffofin da ba su da alaƙa, sunadarai.

Tun da dikodi mai na cikin tsarin da DNA, da za'ayi da Watson da Crick a 1953, za a fara wani tsanani binciken, an gano cewa, deoxyribonucleic acid - shi ne mai polymer da DNA monomers ne nucleotides. Za mu yi nazarin iri da tsari da su a wannan takarda.

Ƙididdigar tsararraki a matsayin raƙuman tsari na ilimin haɗin kai

Ɗaya daga cikin muhimman abubuwan da ke tattare da kwayoyin rayuwa shine adanawa da watsa bayanai game da tsari da ayyuka na tantanin halitta da dukan kwayoyin halitta. Wannan rawar da aka yi deoxyribonucleic acid da DNA monomers - nucleotides wakiltar wani irin "gini tubalan" daga abin da musamman zane da kuma gina abu gadar hali. Bari muyi la'akari da abin da alamun suka shiryar da yanayin rayuwa, samar da wani babban adadin nucleic acid.

Yadda aka kafa nucleotides

Don amsa wannan tambayar, muna buƙatar wasu ilimin daga ilmin sunadaran kwayoyin halitta. Musamman, mun tuna cewa a yanayi akwai rukuni na glycoside heterocyclic nitrogen, wanda ya haɗa da monosaccharides - pentoses (deoxyribose ko ribose). An kira su nucleosides. Alal misali, adenosine da sauran nau'o'in nucleosides suna cikin cytosol na tantanin halitta. Suna shiga cikin samfurin lissafi tare da kwayoyin halittar orthophosphoric. Abubuwan da wannan tsari zai kasance nucleotides. Kowace DNA monomer, da hudu daga cikinsu, suna da suna, misali, guanine, thymine da cytosine nucleotide.

Halitta mai tsabta na DNA

A cikin biochemistry, an karbi rabuwa da ke raba kwayoyin halittar DNA da tsarin su zuwa kungiyoyi biyu: alal misali, purine adenine ne da guanine nucleotides. Sun ƙunshi a cikin abun da ke ciki purine Kalam - Organic abu da ciwon da dabara C ₅ H ₄ N _4. Halitta na DNA, guanine nucleotide, ya ƙunshi magungunan nitrogen na purine guda biyu tare da haɗin linzamin N-glycosid deoxyribose a cikin tsari.

Pyrimidine nucleotides

Gidajen kafa na Nitrogen, da ake kira cytidine da thymidine, sune tushen kwayoyin pyrimidine. Its dabara ne C ₄ H ₄ N _2. Ƙwayar kwayar ita ce ƙwayar heterocycle mai lamba shida da aka ƙunshi nau'i biyu na nitrogen. An san cewa a maimakon ƙarancin kamine na kwayoyin ribonucleic acid, irin su rRNA, tRNA, da mRNA, a cikin nau'in uracil. A yayin aiwatar da rubutun bayanan, yayin da aka share bayanai daga DNA zuwa kwayoyin mRNA, an maye gurbin kajin dinar din din din din din din din din din adinine, kuma adinine nucleotide ya maye gurbin uracil a cikin sarkar mRNA. Wato, shigarwa mai zuwa zai zama daidai: A - Y, T - A.

Dokar Chargaff

A cikin ɓangaren da suka gabata, mun riga mun taɓa kan ka'idodin rubutun duniyoyi a cikin DNA strands kuma a cikin ginin gene-iRNA. Masanin binciken halitta mai suna E.Chargaff ya kafa wani abu na musamman na kwayoyin deoxyribonucleic acid, wato, yawan adenine nucleotides a cikinta yana da daidai lokacin da kamine, da guanine - zuwa cytosine. Babban mahimmanci akan ka'idodi na Chartaff shine binciken Watson da Crick, wanda ya kafa abin da monomers ke haifar da kwayar halittar DNA da kuma abin da suke da shi na asibiti. Wani tsari na yau da kullum, wanda Chargaff ya karɓa kuma ya kira ka'idar hadin gwiwa, ya nuna alamar sunadaran sinadarin purine da pyrimidine da kuma ikon yin hulɗa da juna don samar da haruffan hydrogen. Wannan yana nufin cewa tsari na monomers a cikin siginonin DNA guda ɗaya an ƙaddara shi ne: misali, a gefe guda, za'a iya samun T na farkon DNA kuma tsakanin sassan biyu na hydrogen. Da bambanci da guanine nucleotide, kawai ana iya samun cytosine. A wannan yanayin, tsakanin magunguna na nitrogenous, an kafa shaidu guda uku.

Matsayi na nucleotides a cikin tsarin jinsi

Don aiwatar da maganin kwayar halitta mai gina jiki a cikin ribosomes, akwai wata hanya don fassara bayanai game da abun amino acid na peptide daga jerin nucleotides na mRNA cikin jerin amino acid. Ya bayyana cewa uku sunaye na kusa suna dauke da bayanai game da daya daga cikin 20 amino acid mai yiwuwa. Wannan sabon abu ne ake kira da kwayoyin code. A warware matsalolin kwayoyin halitta, an yi amfani dashi don ƙayyade abu guda amino acid na peptide kuma don bayyana wannan tambaya: abin da monomers ya samar da kwayar halittar DNA, a wasu kalmomi, menene abun da ke cikin jinsi daidai. Alal misali, sau uku (codon) AAA a cikin jigon halitta ya hada da amino acid phenylalanine a cikin kwayar sunadarai, kuma a cikin kundin tsarin kwayoyin zai dace da Ƙa'idar UTU a cikin sarkar mRNA.

Hadin hulɗar nucleotides a lokacin DNA sakewa

Kamar yadda aka bayyana a baya, raka'a tsarin, DNA monomers ne nucleotides. Takaddun takaddun su a cikin sarƙoƙi shine matrix don kira na ƙwayar ƙwayar ƙwayar deoxyribonucleic acid. Wannan sabon abu yana faruwa a cikin S-phase na cell din interphase. A nucleotide jerin labari DNA din a masu juna biyu za sarƙoƙi da enzyme DNA polymerase tare da manufa na complementarity (A - C, A - C). Amfani yana nufin halayen matrix. Wannan yana nufin cewa dodadden DNA da tsarin su a cikin mahaifiyar mata sune tushen, wato, matrix don 'yarta ta kwafi.

Za a iya canza tsarin nucleotide

A hanyar, bari mu ce adin deoxyribonucleic wani tsari ne mai mahimmanci na tsakiya kwayar halitta. Wannan bayani ne mai mahimmanci: bayanan da aka ajiye a cikin zuciyar chromatin ya kamata a canzawa kuma a kwafe shi ba tare da ɓarna ba. Hakanan, kwayar halittar salula ta kasance "ƙarƙashin bindiga" na abubuwa masu muhalli. Alal misali, irin wadannan kwayoyin sunadarai kamar barasa, miyagun ƙwayoyi, radiation radioactive. Dukkanansu suna da ake kira mutagens, a ƙarƙashin rinjayar kowace ƙarancin DNA zai iya canza yanayin sunadarai. Irin wannan rikici a cikin biochemistry an kira shi maye gurbin. Hakanan bayyanar su a cikin kwayar halittar kwayar halitta tana da yawa. Ana gyarawa ta hanyar aiki mai kyau na tsarin gyaran salula, wanda ya haɗa da saiti na enzymes.

Wasu daga cikinsu, alal misali ƙuntataccen enzymes, "yanke" lalacewar nucleotides, polymerases sun tabbatar da kira na ma'auni na al'ada, halayen "sutura" sassan da aka sake dawowa. Idan ma'anar da ke sama don wasu dalili ba ya aiki a cikin tantanin halitta kuma mummunan DNA din din ya kasance a cikin kwayoyinsa, ana maye gurbinwa ta hanyar matrix synthesis processes da phenotypically bayyanar a matsayin sunadarai tare da kayyadadden kaddarorin da basu iya yin ayyukan da ake bukata a cikin su a cikin cellular metabolism. Wannan wani mummunar ma'ana ce, wadda ta rage yawan yiwuwar tantanin halitta kuma ta rage tsawon rayuwarta.