Chemical abun da ke ciki na chromosomes. A tsarin, aiki da rarrabuwa na chromosomes

Chromosomes - shi nucleoprotein Tsarin located a cikin nucleus din eukaryotic Kwayoyin. Suka kuma kiyaye kusan duk kwayoyin bayanai, kuma sũ, a aikin na ta ajiya, canja wuri da kuma aiwatar. Chromosomes ne da wuya a bayyane ko a cikin haske microscope, amma za ka iya gani a sarari a cikin lokaci na cell division a lokacin mitosis da meiosis.

Karyotype da chromosomes dokoki

Karyotype ne sa na duk chromosomes (diploid), suna a cikin wani keji. Shi ne jinsunan-takamaiman, cewa shi ne na musamman don kowane jinsi na abubuwa masu rai a duniya, matakin volatility ne in mun gwada low, amma wasu mutane da wasu fasaloli. Alal misali, wakilan daban-daban mata da maza su ne m m chromosomes (autosomes), bambanci tsakanin karyotypes na daya kawai biyu daga chromosomes - jima'i chromosomes, ko m chromosome.

Sharuddan chromosomes ne mai sauki: adadin su har abada (a cikin somatic Kwayoyin iya ƙunsar kawai wani m yawan chromosomes, misali, Cats - 38, a cikin 'ya'yan tashi Drosophila melanogaster - 8, da kaza - 78, da wani mutum 46).

Chromosomes aka sa su guda biyu kõwane ɗaya daga cikinsu yana da wani homologue biyu, m madaidaci, ciki har da siffar da size. Dabam kawai asalin: daya - daga mahaifinsa, da sauran - daga uwar.

Homologue chromosomes ne mutum nau'i-nau'i: kowane daga cikin nau'i-nau'i ne daban-daban daga wasu ba kawai a cikin bayyanar - da siffar da size - amma kuma wurin da haske da duhu makada.

Ci - wani mulki na chromosomes. DNA ya maimaita Kwayoyin kafin division, sakamakon shi a biyu daga 'yar'uwar chromatids. Kowane 'yar cell bayan division na'am da daya chromatid, cewa an kafa daga chromosome chromosome.

muhimmanci abubuwa

Chromosome, wanda tsari ne mun gwada sauki, an kafa daga DNA kwayoyin ciwon manyan tsawon. Ya qunshi wani jam'i na mikakke kungiyoyin kwayoyin halitta. Kowane chromosome yana da wani centromere da telomeres, kwafi qaddamarwa batu - shi ne wajibi aikin abubuwa. Telomeres ake samu a tukwici na chromosomes. Saboda wadannan da kuma asalin kwafi (wanda kuma ake kira qaddamarwa shafukan), da jigidar halittar DNA za a iya replicated. A wannan na faruwa centromere na 'yar'uwarsa da aka makala na DNA da mitotic dogara sanda division cewa damar da su zuwa daidai watsa' yar Kwayoyin a lokacin mitosis tsari.

game da ƙwayoyin cuta

Kalmar "chromosome" da aka asali samarwa a matsayin nadi na Tsarin hali na eukaryotic Kwayoyin, amma masana kimiyya suna ƙara ambata kwayar kuma kwayan chromosome. A abun da ke ciki, ayyuka ne kusan guda, don haka DE Koryakov da I. F. Zhimulov yi imani da cewa ra'ayi ya dade da zama dole, don kara fadada da kuma ayyana chromosome ne a tsarin hada da nucleic acid da kuma ciwon ajiya aiki da aiwatarwa da kuma canja wurin da gene bayanai. A eukaryotes, chromosomes dauke a cikin nucleus din, kazalika da plastids da mitochondria. Prokaryotes (maras makaman nukiliya) ma dauke da DNA, amma ba a cikin cell tsakiya. Ƙwayoyin cuta chromosomes da wani nau'i na kwayoyin na RNA ko DNA, dake a cikin capsid. Ko da kuwa da kasancewar a cikin cell tsakiya na chromosomes ne kwayoyin abubuwa, karfe ions da kuma wasu abubuwa.

Tarihi na samu

Masana kimiyya sun zo dogon hanyar da tafi kafin yayi nazari chromosomes. Suna farko aka bayyana a cikin seventies na karshe karni: daban-daban mawallafa sun ambata su a cikin articles, littattafai da kuma gudanar da bincike takardunku, don haka gano chromosomes aka dangana ga mutane daban-daban. A wannan jerin sunayen I. D. Chistyakova, Alexander Schneider, O. Butschli E. Strasburger, da kuma waɗansu da yawa, amma mafi malamai gane 1882 a matsayin shekarar da gano chromosomes, ya kira wani majagaba W. Fleming, mai Jamus anatomist wanda ya tattara da kuma shirya bayanai na chromosomes a cikin littafinsa Zellsubstanz, Kern und Zelltheilung, ƙara wa riga data kasance bayanai nasu karatu. The sosai guda lokaci da shawarar a 1888 da Mr. Heinrich Wilhelm Gottfried von Waldeyer-Hartz histologist. Fassara chromosome nufin zahiri "a canza launin jiki". Sunan shi ne saboda gaskiyar cewa sinadaran abun da ke ciki na chromosomes damar da shi zuwa ga sauƙi daura asali dyes.

A shekarar 1900, an "sake gano" Mendel da dokokin, da kuma sosai da ewa ba, a cikin shekaru biyu, masana kimiyya sun ƙarasa da cewa chromosomes a lokacin meiosis da kuma hadi matakai hali kamar "barbashi gadar hali" wanda hali da aka rubuce da aka bayyana a baya. A 1902, da kansa da juna, da kuma T. Boveri W. Setton an hypothesized cewa chromosome tsarin abin da yake har yanzu ba a sani ba, yana mai aiki aika da kuma adana kwayoyin bayanai.

Drosophila da yabanyarta

A farko kwata karni na karshe da aka alama ta gwaji tabbatar da ra'ayoyin da cewa chromosomes da kayyade rawa. American masana kimiyya T. Morgan, A. Sturtevant, C. Bridges kuma H. Muller yi aiki a kan bincike ayyukan, wanda sun zama abubuwa da rarrabuwa tsarin chromosomes da su aiki. Gwaje-gwaje da aka yi a kan D.melanogaster, da aka sani shi ne watakila dukan 'ya'yan itace gardama. A samu data kasance dalilin da chromosomal ka'idar gadar hali, wanda shi ne ya dace ko a yanzu, bayan kusan shekara ɗari daya. A cewar ta, da chromosome dangantawa da kwayoyin bayanai, da kuma kwayoyin halittu suna sarrafa a cikin mikakke jerin a sarari ba, amma da sinadaran abun da ke ciki da kuma ilimin halittar jiki na chromosomes ake karatu da masana kimiyya a kwanakin nan namu.

Domin aikin T. Morgan aka bayar da Nobel Prize a Physiology ko Medicine a 1933.

Chemical abun da ke ciki na chromosomes

Yana za a iya takaita da cewa kwayoyin abu a cikin chromosomes bayyana a matsayin nucleo-gina jiki hadaddun. Bayan nazarin sinadaran kungiyar na chromosomes a eukaryotic Kwayoyin, masana kimiyya iya cewa sun kunshi ga mafi part na DNA da sunadaran cewa, samar da nucleo-gina jiki hadaddun kira chromatin.

Sunadaran shigar da abun da ke ciki na chromosomes, shi ne wani gagarumin bangare na duk kwayoyin halitta a cikin chromosomes, game da 65% na jimlar nauyin Tsarin da dama a kan su. Chromosomal sunadaran ya kasu kashi ba-histone sunadaran da histone. Histones - karfi tushe, alkaline a cikin yanayi su sa ta gaban lysine da argenina - da muhimmanci amino acid.

A sunadarai da kuma tsarin abun da ke ciki na chromosomes bambanta. Histones ne biyar ƙungiyõyin: Hl, H2A, H2B, H3 da H4. All amma na farko sulusi da murabba'i in kamar daidai yawa suna samuwa a cikin sel duk nau'in na zuwa mafi girma dabbobi masu shayarwa. Hl sunadaran kasa da rabi.

Kira na histone auku a cytoplasmic polysomes. Wannan asali da sunadarai da ciwon tabbatacce cajin, saboda wanda za a iya alaka da tabbaci tare da DNA din, kuma haka ba su bayar da wani karanta a kewaye hereditary bayanai. Wannan shi ne dokokin rawar da histones, amma a Bugu da kari shi ma yana da wani tsarin aiki, saboda abin da aka bayar da sarari kungiyar na DNA a chromosomes.

Da hankula sinadaran abun da ke ciki na Interphase chromosomes kuma kunshi da ba-histone sunadaran, wanda, bi da bi, an raba da fiye da dari kasarun adadi. A cikin wannan jerin hada da enzymes alhakin kira na RNA, kuma enzymes cewa fara gyara da kuma reduplication DNA. Kazalika da asali, acidic chromosomal sunadaran da tsarin ba da tsaiko aiki.

Duk da haka, da sinadaran abun da ke ciki na chromosome ba ya kawo karshen: mai gina jiki da kuma DNA a RNA ba abun da ke ciki, karfe ions, lipids, kuma polysaccharides. Sunny chromosomal RNA ba kamar yadda transcriptional kayayyakin cewa ba tukuna bar kira wuri.

a metaphase

Morphological siffofi metaphase chromosomes kamar haka: a lokacin farkon rabin mitosis suka kunshi nau'i-nau'i daga 'yar'uwar chromatids, wanda ake juna a cikin centromere yankin (primary constriction ko kinetochore) - shi ne wani ɓangare na chromosome cewa yake ga kowa da biyu chromatids. A sunadarai abun da ke ciki na chromosome ne ma canza. The biyu da rabi na mitosis halin chromatid rabuwa, bi da samuwar guda-stranded ya chromosomes, wanda aka rarraba wa 'yar Kwayoyin. Tambayar da nawa DNA wani bangare ne na metaphase chromosomes, kowa a gwaje-gwaje a cikin ilmin halitta da kuma gagare dalibai. A karshe zamani na Interphase da prophase da metaphase chromosomes dvuhromatidny, don haka suka kafa da dabara 2n4c.

rarrabuwa na chromosomes

A matsayi na centromere da tsawon da makamai, wanda ake located a kan ko dai gefen ta chromosomes suna classified kamar yadda metacentric (L-daidai) idan centromere aka located tsakiya da kuma submetacentric (neravnoplechie) idan centromere aka canja zuwa daya karshen. Har ila yau, akwai acrocentric, ko sanda-dimbin yawa chromosome (centromere sun located kusan a sosai karshen) da kuma ma'ana chromosome, mai suna domin ta kananan size, don haka da cewa shi ne kusan ba zai yiwu ba domin sanin su siffar. A telotsentricheskih chromosomes ma wuya a ƙayyade wurin da primary constriction wuri.

compaction

Duk wani somatic cell ƙunshi 23 nau'i-nau'i daga chromosomes, kowanne daga abin kunshi guda jigidar halittar DNA. A total tsawon na 46 kwayoyin ne game da mita biyu! Wannan shi ne fiye da uku biliyan tushe nau'i-nau'i, kuma suka duk shige zuwa cikin daya cell, da chromosomes a lokacin Interphase kusan indistinguishable ko da a wani na'urar hange. Dalilin wannan - da supramolecular kungiyar na chromosomes, ko compaction. A miƙa mulki ga wani daban-daban lokaci na cell sake zagayowar chromatin iya canza ta kungiyar.

A tsarin da kuma sinadaran abun da ke ciki da kuma tsarin da Interphase chromosome metaphase chromosomes masana kimiyya dauke bambance-bambancen karatu a matsayin iyakacin duniya Tsarin wanda aka ciri da juna a mi} a lokacin mitosis tsari.

A farko matakin da aka wakilta nucleosome compaction thread, wadda kuma ake kira "beads a kan wani kirtani". A halayyar size - 10-11 nm, wanda ba ya ba da damar a yi la'akari da su a karkashin wani hange.

Chemical abun da ke ciki na chromosomes kayyade gaban wannan matakin na kungiyar: shi na samar da hudu iri histones - core sunadaran (H2A, H2B, NC, N4). Sai suka samar da wani ɓawon burodi - jikin sunadarai na gina jiki dimbin yawa washers. Kowane ɓawon burodi kunshi takwas kwayoyin (tururi kwayoyin daga kowace histones).
Faruwa DNA taro, shi ne spirally rauni a kan haushi. Tare da kowace lamba jiki sashi da furotin da jigidar halittar DNA yana da 146 nucleotide nau'i-nau'i. Akwai ba takara a lamba yanki, da ake kira linker, ko binders. Su size dabam, amma talakawan ne 60 nau'i-nau'i daga nucleotides (n. N.).

Kira nucleosome DNA yankin da ciwon tsawon na 196 BP kuma ya hada da gina jiki bawo. Duk da haka nucleosome filament yarn-kamar beads, da kuma wani yankin ba dauke da bawo.

Irin wannan rabo wanda rarrabe daidai ba histone sunadarai, saboda da gaban takamaiman nucleotide jerin ne quite gaba ɗaya a kan jinkiri na 'yan dubu tushe nau'i-nau'i. Su gaban yana da muhimmanci ga kara compaction na chromatin.

Bugu da ari shiryawa na chromatin

Chromatin fibril - compaction biyu matakin - kuma kira wani solenoid, ko nukleomernym matakin. Girman ne 30 nm. Bayar histone HI. Ya teams har da wani linker DNA jerin, kazalika da biyu dake makwabtaka da crusts da kuma "jan" su tare. A sakamakon samuwar tsari zama fiye da m tsarin kamã da tsarin a solenoid. Irin wannan fibril, a Bugu da kari ga chromatin aka kira na farko.

Bi hronomerny matakin. A halayyar girman da matakin na compaction - 300 nm. Riga babu wani ƙarin Helix samuwar, amma samar da giciye hinges cewa yayi daidai da size of guda replicon da ake hada ta wajen ba histone (acidic)

A hromonemnom matakin (700 nm) na madauki converge, har ma fiye da kompaktiziruetsya chromatin. Ilimi strands na chromosomes ne riga bayyane a cikin haske hange.

Chromosomal Layer (1400 nm) an kiyaye a lokacin metaphase.

Maye gurbi, kuma rawar da suka taka a magani

The maye gurbi na chromosomes - ba nadiri, amma na iya samun wani daban-daban digiri da sunadaran da. Canje-canje a cikin tsarin nau'i na chromosomes ana dogara ne a kan na farko breakage. Idan akwai karyewar a chromosome, sa'an nan da jiki yana da samar da su sake fasalin kudin, tare da sakamakon cewa akwai wani chromosomal maye gurbi ko daɗaɗɗa.

A lokacin crossover homologue chromosomes musanya dacewa yankunan, da kuma shi karya yawanci faruwa a wannan lokaci. Idan, yayin lokacin musayar unequal mararraba-kan rabo daga cikin kwayoyin halitta, sabon hadin kungiyoyin.

iri maye gurbi

Akwai da dama iri maye gurbi bisa ginshikai na asali. Maye gurbi na fission bayyana saboda asarar gene segments. Idan wasu sassa na genome aka ninka - wannan kwafi. A lokacin inversion na chromosome tsakanin discontinuities rabo ne juya su ta hanyar 180 °.

Translocation kira mika mulki yanki daga daya chromosome zuwa wani, kuma idan hijirar ya auku tsakanin wadanda ba homologue chromosomes, da ake kira na juna translocation, kuma idan gutsure aka shiga zuwa guda chromosome maye gurbi kira transposition. A lokacin Robertsonian translocation auku daidaituwa a cikin daya daga biyu ba homologue Tsarin.

Akwai kuma maye gurbi pericentric da paracentric.

RNA

Dangane da lokaci a cikin abin da cell, canza sinadaran abun da ke ciki, ilimin halittar jiki, halaye da kuma size of chromosomes, amma kayyade abu ya ƙunshi ba kawai DNA da chromosomes a tsakiya.

Ribonucleic acid (RNA) - wani tsarin musharaka a canja wuri da kuma ajiya na kayyade bayani.

Akwai mRNA ko mRNA (matrix, ko bayanai), shi ke taka rawa a cikin kira na sunadaran da ake so Properties. Domin wannan shi ne cewa wajibi ne wurin da "yi" samu "umarnin", wadda za ta gaya wa domin samar da amino acid ne da za a hada a cikin peptide sarkar. Wannan wa'azi bayanai da aka shigar wanda ke aiki a cikin nucleotide jerin mRNA (mRNA). Kwafi da ake kira manzo RNA kira.

A tsari na karatun bayanai daga DNA za a iya kwatanta ta da kwamfuta shirin. Da farko RNA polymerase kiran kasuwa kamata gane - musamman rabo daga cikin jigidar halittar DNA, wadda kiwon farkon na kwafi yankin. RNA polymerase binds ga mai kiran kasuwa da kuma farawa unwinding da m juya-Helix DNA. A wannan lokaci, biyu strands na DNA An katse ka daga juna, sa'ilin da enzyme mRNA samuwar fara ranar daya daga cikinsu (kodogennoy ta da enzyme 3`-karshen). Ribonucleotides tattara a sarkar mulkin complementarity da nucleotides na DNA da antiparallel tare da girmamawa ga template DNA tufka.

A tsari na kwafi

Saboda haka, kamar yadda muka matsa tare da DNA tufka, da enzyme daidai karanta duk bayanai, da ci gaba da aiwatar da har wani sabon sadu da takamaiman jerin nucleotides. Shi ne ake kira da terminator transkripktsii, da kuma nuna cewa RNA polymerase ya kamata a rabu da DNA da template tufka, kuma daga sabuwar hada mRNA. Sum cikin yankunan da kiran kasuwa zuwa terminator ciki har da rubuce rabo kira kwafi guda ɗaya - transcriptional.

Da zaran RNA polymerase motsa tare kodogennoy sarkar rubuce guda-stranded yankuna na DNA hada da sake daukar wani nau'i na biyu Helix. Kafa mRNA daukawa ainihin kwafin na data kofe daga cikin DNA sashe. Nucleotides na mRNA shigar da amino acid jerin suna harhada a threes da ake kira codons. Kowane codon na mRNA m zuwa wani amino acid.

Properties da kuma aiki na genes

A gene aka dauke su basa firamare aikin raka'a gadar hali-abu. Yana yana da wani nau'i na jigidar halittar DNA da rabo da aka shigar wanda ke aiki tsarin akalla daya peptide.

A gene yana da wasu Properties, na farko daga cikinsu - wani mai hankali mataki. Wannan yana nufin cewa daban-daban genes sarrafa ci gaban sarrafa ãyõyi ga mutane.
da haƙuri da dukiya ƙaddara da gaskiya cewa gene ne canzawa tare da hereditary watsa, sai dai in, ba shakka, babu maye gurbi. Daga wannan shi ya bi cewa gene ba za a iya canza a lokacin da rai.

The bayani dalla-dalla na mataki ne saboda ci gaban da siffa ko rukuni na siffofin, amma genes iya samun mahara da kuma mataki - wannan ne ake kira pleiotropy.

Property dosing mataki kayyade har zuwa abin da wata ãyã iya ci gaba saboda genome.

Su ma halayyar da allelic jihar, wato, kusan duk na genes ne alleles, wanda lambar fara da biyu.