Ayyukan chromosomes da tsarin su. Mene ne aikin chromosomes a tantanin halitta?

Wannan labarin zai magance tsarin na eukaryotic Kwayoyin, chromosomes, sifa da aiki suna karatu ilmin halitta masana'antu, da ake kira cytology.

Tarihin binciken

Kwayoyin, manyan sassan tsakiya, sun samo asali daga chromosomes a cikin karni na 19 ta hanyar masana kimiyya. A Rasha halitta I. Chistyakov karatu su a lokacin mitosis (cell division), Jamus anatomist Heinrich Wilhelm Gottfried von Waldeyer-Hartz gano su a lokacin shiri na histological shirye-shirye da kuma kira chromosomes, cewa an batawa yan maruƙa domin saurin martani daga wadannan Tsarin cikin hulda da kwayoyin fenti magenta.

Fleming ya taƙaita hujjojin kimiyya game da aikin da chromosomes ke yi a cikin kwayoyin da suka kafa tsakiya.

Tsarin waje na chromosomes

Wadannan samfurin microscopic suna samuwa a cikin kwayar halitta - kwayoyin mahimmanci na tantanin halitta, kuma suna zama wuri don adanawa da aikawa bayanan da ke tattare da wannan kwayar halitta. Chromosomes sun ƙunshi abu na musamman - chromatin. Yana da wani nau'i na filaments mai kyau - fibrils da granules. Daga mai guba bisa, wannan fili na mikakke DNA kwayoyin (game da 40%) tare da takamaiman histone sunadaran.

Ƙungiyoyi da suka hada da kwayoyin 8 da peptides da DNA, sun juya a kan ginshiƙan furotin, kamar yadda ake amfani da su, an kira nucleosomes. Plot deoxyribonucleic acid da ya ƙunshi 1,75 juyin kusa da shaft rabo kuma yana da nau'i na wani ellipsoid game da 10 nanometers a tsawon kuma 5-6 a fadin. Kasancewar wadannan siffofi (chromosomes) a cikin tsakiya suna aiki ne a tsarin kwayoyin halitta na eukaryotic. Ya kasance a cikin nau'i nau'in halitta cewa chromosome yana aiki na karewa da kuma aika dukkanin dabi'a.

Dangane da tsari na chromosome a kan lokaci na tantanin halitta

Idan tantanin halitta ya kasance a cikin wani matsayi na interphase, wanda yake nuna ci gabanta da kuma ciwo mai tsanani, amma rashin rabuwa, to, chromosomes a cikin tsakiya suna da nau'i na bakin ciki, da furo-fure, da chromone. Yawancin lokaci an haɗa su, kuma ba zai yiwu ba a raba su cikin sassan daban. A farkon lokacin rarrabawar sel, wadda ake kira mitosis a cikin sel mai tarin hankali, da kuma tasiri a cikin jima'i, chromosomes sun fara farawa kuma sunyi girma, sun zama masu rarrabe a cikin wani microscope.

Matsayi na ƙungiyar chromosome

Ƙungiyoyin halayen su ne chromosomes, kimiyyar kwayoyin halitta tana nazarin cikakken bayani. Masana kimiyya sun ƙaddara cewa nauyin halitta da ke dauke da DNA da sunadaran histone suna samar da helix na farko. Kullin kullun chromatin yana faruwa ne saboda kafa tsarin tsari mafi girma - mai sunnool din. Ya shirya kansa kuma ya haɗa da shi a cikin babban mahimmanci-helix. Dukkanin matakan da ake gudanarwa na ƙungiyar chromosome sun wuce yayin shiri na tantanin halitta don rarraba.

Yana cikin juyayi na mitotic cewa sassan tsarin ladabi, wanda ya ƙunshi jinsin da ke dauke da DNA, an ragu da kuma ɗaukakke idan aka kwatanta da chromons mai yatsun na tsawon lokacin interphase ta kimanin sau 19,000. Wannan m siffan chromosome kwaya ayyuka waxanda suke don canja wurin kwayoyin halaye da kwayoyin, suna shirye su raba somatic ko jam sel.

Mafarki na chromosomes

Ayyukan chromosomes za a iya bayyana ta hanyar nazarin siffofin siffofi, waɗanda aka fi kyau a cikin juyi na mitotic. An tabbatar da cewa ko da a cikin lokaci na haɗi na interphase, yawan DNA a tantanin tantanin halitta sau biyu, tun lokacin da ɗayan 'yar salula da aka samo asali daga rabuwa dole ne su sami adadin abubuwan da ke tattare da su a matsayin asalin asali. Ana samun wannan sakamakon sakamakon tsarin sabuntawa - haɓakawa na DNA, wanda ke faruwa tare da haɓakar DNA polymerase enzyme.

A cikin shirye-shiryen cytological da aka shirya a lokacin mitosis metaphase, a cikin shuka ko dabbobin dabba a karkashin wani microscope an gani a sarari cewa kowane chromosome ya ƙunshi sassa biyu da ake kira chromatids. A cikin karin hanyoyi na mitosis-anaphase kuma, musamman ma, telophase-cikakkiyar rabuwa ta auku, sabili da haka kowane chromatid ya zama chromosome daban. Ya ƙunshi kwayar halittar DNA wadda aka haɗa ta gaba, da lipids, sunadaran acid da RNA. Daga cikin abubuwa ma'adinai a cikinta akwai ions na magnesium da alli.

Abubuwan da suka dace na tsarin chromosome

Wannan tsarin da ake gudanarwa a cikin tantanin halitta ya cika, waɗannan ragamar ƙirar suna da ƙwarewar musamman - ƙaddamarwa ta farko (centromere), wadda ba ta ɗorawa ba. Ita ce wadda ta rarraba chromosome cikin sassa biyu, wanda ake kira kafadu. Dangane da yanayin da ake ciki, kwayoyin suna rarraba chromosomes zuwa equinox (metacentric), wadanda ba su daidaita (sub-metacentric), da kuma adrocentric. A kan ƙananan wuyansa, ƙirarrun ƙwarewa an kafa su ne, wanda shine siffofin furotin da aka fice a gefen biyu na centromer. Hakanan sun hada da sassan biyu: ƙananan lambobin sadarwa tare da microfilaments (filament spindle fibers), sun haɗa su.

Saboda rage yawan zaren (microfilaments), an rarraba kundin chromatids mai karfi da aka tsara a tsakanin 'yan' yarinyar. Wasu chromosomes suna da mahimmanci guda biyu ko fiye da sakandare wanda ba su shiga cikin masihu, tun da ba za su iya haɗa su da filayen filament ba, amma waɗannan sassa (na biyu) sun ba da iko akan kiran nucleoli - organelles, wanda ke da alhakin samuwar ribosomes.

Menene karyotype?

Masanan kimiyyar kwayar halitta Morgan, N. Koltsov, da kuma Setton a farkon karni na 20 sunyi nazarin chromosomes, tsarin su da ayyukansu a cikin jima'i da jima'i. Sun gano cewa kowace kwayar halitta ta kowane jinsin halittu tana da alamun wasu adadin chromosomes, suna da siffar da girman su. An nuna cewa dukan jinsin chromosomes a tsakiya na tantanin halitta ana kiransu karyotype.

A cikin wallafe-wallafen wallafe-wallafe, ana nuna alamar karyotype tare da tsarin chromosome. A gaskiya ma, waɗannan ba ainihin ra'ayi ba ne. Alal misali, a cikin mutum, karyotype ne 46 chromosomes a cikin dakin ƙwayoyin salula mai tsayi kuma an tsara shi ta hanyar dabarar 2n. Amma irin waɗannan kwayoyin, kamar misalin hepatocytes (hanta Kwayoyin) suna da nau'o'in nau'o'i, an kafa sashen chromosomal kamar 2n * 2 = 4n ko 2n * 4 = 8n. Wato, adadin chromosomes a cikin waɗannan kwayoyin zasu zama fiye da 46, ko da yake karyotype na hepatocytes ne 2n, wato, 46 chromosomes.

Yawan adadin chromosomes a cikin kwayoyin kwayar halitta ko da yaushe rabin kamar yadda a cikin kwayoyin sunadarai (a cikin jikin jikin), irin wannan tsari ana kiransa halloid kuma an sanya shi azaman n. Duk sauran kwayoyin jiki suna da saitin 2n, wanda ake kira diploid.

Ka'idar Chromosome na al'adun Morgan

American jini Morgan gano dokar nasaba gado kwayoyin halitta, gudanar da gwaje-gwajen a kan hybridization na 'ya'yan kwari,' ya'yan kwari. Godiya ga bincikensa, ana nazarin ayyukan chromosomes na kwayoyin germ. Morgan ya tabbatar da cewa jinsin da ke kusa da wannan ƙwayar chromosome an hade shi ne, wato, haɗin. Idan jinsin suna da nisa da juna a cikin ƙwayoyin cuta, to, hanyar musayar mawuyacin 'yar'uwa zai yiwu a tsakanin' yan uwan mata.

Mun gode da binciken Morgan, an tsara taswirar kwayoyin halitta don taimakawa wajen nazarin ayyukan chromosomes kuma yada amfani da su a cikin shawarwarin kwayoyin don magance cututtuka na chromosomes ko kwayoyin da ke haifar da cututtuka a cikin mutane. Muhimmancin shawarar da masanin kimiyya ya yi ya kasance mai wuya ga karimci.

A cikin wannan labarin mun bincika tsarin da ayyuka na chromosomes, wanda suke yi a tantanin halitta.