Tarihin sune ... Tarihin tarihin DNA

DNA nucleic acid, wanda ya shiga cikin kwayoyin halitta na eukaryotic, an ƙaddara shi sosai saboda tsari na musamman. A cytology suna da suna na musamman - histones. Wadannan su ne peptides da ke nuna alamun sunadarai na asali. Za'a tattauna batun da ayyukansu da aka gudanar a tantanin halitta a cikin wannan labarin.

Yadda aka tsara DNA a tsakiya

Domin "matsi" dogon polynucleotide sarkar DNA a microspace cell tsakiya , a cikinta akwai peculiar "nada" - sunadarai, histones. Suna biyu-stranded yarn aka rauni deoxyribonucleic acid. Irin wannan tsari, wanda ke cikin karyoplasm, ana kiranta nucleosome. Binciken biochemical ya kafa cewa an gina furotin histone ta hanyar sauyawa: histone H1 / H5, H2A, H2B, H3, H4. Peptide na farko daga wannan jerin ana kiran shi mahaɗi ne, sauran su ne crustaceans. Wadannan sunadaran gina jiki wadanda ke haifar da kwayoyin halitta.

Faculiarities na tsarin da nucleosome peptides

Sakamakon sunadarai sun tabbatar da gaskiyar abubuwan da suka wuce a cikin ainihin tarihin kwayoyin irin wannan amino acid kamar lysine da arginine. Na farko shi ne wanda ba a iya canjawa, kuma ɗayan ya zama mai maye gurbin kuma yana cikin kusan dukkanin peptides. Tarihin sunadarai sun haɗu da ƙananan haɗari akan ƙwayoyin amino acid. Sun shafe mummunan zargin na jimlar PO ₄ ^3- anions, na kunshe a cikin DNA. Wani sashi na tsarin wadannan sunadarai shi ne cewa kusan dukkanin kwayoyin dake cikin mulkin shuka, dabbobi da namomin kaza.

Tunda tarihi shine sunadarai na tsakiya, su, saboda tsarin su, zasu iya shiga cikin matakan da ke faruwa a cikin karyoplasm. Alal misali, mafi mahimmanci ga tsarin karatun shine peptide H1, furotin histone wanda ke riƙe da nucleosomes wanda ke cikin ɓangaren chromatin a cikin tsari mai tsaftace-umarni. Har ila yau, a game da lalacewar DNA loci, abin da ake kira ƙwayoyi masu bambanta daga cikin peptides na tsakiya suna cikin gyaran waɗannan shafuka.

Cow peptides

Sun ƙayyade tsarin tsarin kwayar halitta, wanda ya ƙunshi nau'ikan kwayoyi hudu da ake kira H2A, H2B da H3 da H4. A cikin nucleosomes akwai kwayoyi guda biyu na kowane nau'i, ana kiran wannan tsari dashi. La'idodin kwayoyin deoxyribonucleic da kuma sunadaran sunadarai suna samar da hydrophobic, hydrogen da covalent a tsakaninsu. Tushen sunadarai sune ainihin kwayar halitta. Har ila yau suna dauke da hanyoyi NC-waɗanda ba a gina ba. Wadannan sassa sun hada da sharan amino acid 15-30 da kuma shiga cikin sassan epigenetic da ke sarrafa maganganun kwayoyin halitta. Babban tushen tarihi na tsakiyar ɓangaren ƙwayoyin halitta yana da ƙananan nau'ikan kwayoyin halitta; a cikin sassansu, ba kamar sutsi ba, akwai wasu tsibirin mai gina jiki na hydrophobic: valine, proline, lezine, methionine.

Sabuwar binciken kimiyya a fagen ilmin halitta ya haifar da bayyanar wata kalma ta histone. Ba kamar layin kwayoyin halitta ba, wanda shine duniya don dukan nau'o'in salon salula a duniya, lamarin histone yana da sauƙi. Wannan kalma yana nufin gyaran sassa na wutsiya na peptides saboda sakamakon halayen acetylation, methylation, phosphorylation. Dukkanin matakan sunadaran da ke sama sun faru ne a gaban cibiyoyi masu yawa. Mun gode wa irin wadannan matakai na biochemical da ke gyara ainihin tarihin, maganganun maganganu na kwayoyin da ke kula da halayen da ke tattare da kwayoyin halitta wanda ke dauke da DNA: gyare-gyare, rubutun kalmomi, sabuntawa na faruwa. Tsarin chromatin kanta a ƙarƙashin rinjayar canje-canje a cikin tarihin histone yana shafar sakewa, wato, canza canjin sa a cikin ƙwayoyin halitta (ya rage shi ko kuma, a wani ɓangare, ya rabu).

Furotin din Linker

Histone H1, wanda yake cikin chromatin, ya haɗu tare da ɓangaren ɓangaren ƙwayoyin halitta kuma yana riƙe da shi super-helix na deoxyribonucleic acid. Ana gyara shi a wuri na wani mai kwakwalwa wanda ya kunshi kwayoyin biyu na peptide H3 da kwayoyin biyu na H4. A cikin wakilan jinsunan tsuntsaye da kuma nau'in dabbobi masu rarrafe a cikin erythrocytes, an gano wani haɗin H5 da aka danganta a maimakon tarihin H1.

Hidden H1 yana ƙunshe da wani yanki na HMJB, yanki na tsarin kimanin aminan acid 80. Ya kusan kamar haka a yawancin kwayoyin, ciki har da tsire-tsire, dabbobi da mutane. Wannan yanki ba batun gyare-gyare kuma shi ne ra'ayin mazan jiya. Peptide H1 yana da siffofin siffofi guda biyu: an haɗa shi a cikin nau'i na duniya kuma an tura shi - a cikin takaddama. Wannan na faruwa a yayin da aka haɗa da yankin C-muni na tarihi tare da yankunan DNA-ɗaure. Peptide mai haɗin kai yana taka rawar gani a cikin sake rubuta bayanai daga gwanin zuwa kwayoyin mRNA, a cikin hanyoyin aiwatar da duplication na DNA, da kuma gyaran lalacewar lalacewa. Wannan shine tasirin rayuwa na tarihin DNA.

Yaya sunadarai sun zama octamer

Ba kamar peptide H1 ba, da sauran nau'ikan tarihi, wanda ake kira crustaceans, ana nuna su da isasshen filastik da siffofin bambancin. Alal misali, H2A yana da yawancin canje-canjen: H2AZH2AX MACROH2A. Sun bambanta a tsakaninsu:

• Cutar amino acid C-amino.
• Yanayi a cikin jikin jini.

Alal misali, tarihin bambancin H2ABbd yana da dangantaka da chromatin, a cikin takardun DNA wanda aka samo asali. Maptide na MACROH2A yana samuwa a cikin interromese chromosomes. Nazarin halittu na tarihi sun nuna cewa tarihi na H4 ba shi da siffofin bambanci, amma yana iya ƙirƙirar adadi mai yawa tare da sauran sunadaran shiga cikin kasusuwan kwayoyin halitta. Sabili da haka, masana kimiyya sunyi imanin cewa tarihi sune rukuni na sunadarai na musamman wanda ya shiga cikin tsarin kwayoyin halitta na rayuwa.

Yaya bayani game da tarihi a cikin jinsin da aka adana

Yana iya jãyayya da cewa shanu, da kuma linker histone bambance-bambancen shigar wanda ke aiki a gene gungu da aka bayyana a cikin roba lokaci na cell ta rayuwa sake zagayowar. Alal misali, ga ɗan adam, ƙungiyar mai kula da asusun, wanda ake kira HIST1, ya ƙunshi kwayoyin 35 da aka gano a cikin kashi biyu na biyu na chromosomes. Cluster HIST2 ya ƙunshi nau'i shida da ke rufe tarihi kuma an samo shi a cikin ɓangaren farko na chromosome. Har ila yau ya ƙunshi wurin HIST3, wanda ya hada da kwayoyin guda uku. A cikin sha biyun na biyu, akwai nau'in daya da ke kewaye da histone H4. Abin sha'awa shine, kwayoyin halittun sunadarai ba su da tasiri, kuma jinsunan abubuwan tarihi daban-daban, a akasin haka, suna dauke da su kuma an warwatse su a cikin kwayar halitta.

Don taƙaitawa, mun tabbata cewa tarihi su ne sunadarai da suka hada da aiwatar da helix DNA a tsakiya, kazalika da tsari, gyare-gyare da kuma bayanan rubutu da ke faruwa a ciki.