Meiosis da manziloli. Halayyar bulan na meiosis. Sake bugun daga kwayoyin. Kamance mitosis da meiosis

Game da rayayyun kwayoyin halitta, an san cewa su numfashi, ci, haifa ya kuma mutu, wannan shi ne nazarin halittu aiki. Amma saboda abin da ya ke duk faruwa? A kudi na gini tubalan - Kwayoyin, wanda kuma numfashi, ci, sake fitarwa da mutuwa. Amma ta yaya wannan ya faru?

A tsarin da cell

Yana da aka hada da tubalin tubalan ko rajistan ayyukan. Kuma jiki za a iya raba na farko raka'a - Kwayoyin. Duk da bambancin abubuwa masu rai ne saboda su, bambanci ta'allaka ne kawai a da lambar kuma irin. Sun kunshi tsoka, kashi, da fata, ciki gabobin - sosai da suka sãɓã wa jũna a cikin wa'adinsu. Amma ko da kuwa abin da ayyuka suna yi da daya ko wani cell, dukkan su suna shirya game da wannan. Da farko, da wani "tubali" yana da wani harsashi da armashi, a cikin cytoplasm tare da wasu gabbansa. Wasu Kwayoyin ba su da nuclei, suna kira prokaryotic, amma suna fiye ko žasa da ci gaban da kwayoyin hada da eukaryotic ciwon tsakiya a cikin abin da kwayoyin bayanai da aka adana.

Wasu gabbansa located in cytoplasm, ne bambance bambancen da ban sha'awa, da suka yi da muhimmanci ayyuka. A dabba Kwayoyin asirce endoplasmic reticulum, ribosomes, mitochondria, Golgi na'ura, centrioles, lysosomes da propulsion abubuwa. Tare da su zo duk da matakai da tabbatar da aiki na jiki.

cell aiki

Kamar yadda riga ya bayyana, duk live ciyarwa, numfasawa, kuma ya mayar da, kuma ya mutu. Wannan gaskiya ne duka biyu ga dukan kwayoyin, wato, mutane, da dabbobi, da shuke-shuke da sauransu. D., Kuma zuwa ga Kwayoyin. Yana da ban mamaki, amma kowanne "tubali" yana da wani rai da kansa. Saboda da wasu gabbansa da shi yana karɓa da kuma recycles gina jiki, oxygen, ta kawar da duk wuce haddi daga. Ta cytoplasm da endoplasmic reticulum yi da kai aiki, mitochondria ne alhakin ciki har da numfashi, kazalika da samar da makamashi tsaro. Golgi hadaddun da hannu a jari da kuma fitarwa Kwayoyin na sharar gida kayayyakin. A sauran wasu gabbansa ma hannu a cikin hadaddun matakai. Kuma a wani mataki na cell rai sake zagayowar fara raba, to, a can ne tsari na haifuwa. Shi ne ya cancanci a duba a cikin mafi daki-daki.

A tsari na cell division

Sake bugun - daya daga cikin matakai na raya kasa na mai rai gabar. Haka ya shafi cikin Kwayoyin. A wani mataki na rayuwa sake zagayowar aka hada a jihar a lokacin da suka zama shirye su yi kiwo. Prokaryotic Kwayoyin kawai ya raba biyu, ya mika, sa'an nan su kafa wani shãmaki. Wannan tsari ne mai sauki kuma kusan gaba daya gane da misali sanda-dimbin yawa kwayoyin.

Tun eukaryotic Kwayoyin halin da ake ciki shi ne mafi rikitarwa. Su asali a cikin uku hanyoyi daban-daban, da ake kira amitosis, mitosis da meiosis. Kowace daga cikin wadannan hanyoyi na da halaye, shi ne muhimmi a cikin wani irin cell. amitosis An dauke da mafi sauki, an kuma kira a kai tsaye binary fission. Lokacin da akwai wani cire tallafin cikin jigidar halittar DNA. Duk da haka, division dogara sanda ba kafa, don haka da cewa wannan hanya ne mafi energetically tattali. Amitosis lura a unicellular kwayoyin, yayin da kwayar nama propagate ta hanyar sauran sunadaran. Duk da haka, shi ne, wani lokacin ya lura da kuma inda ya rage mitotic aiki, misali, a cikin balagagge kyallen takarda.

Wani lokaci kai tsaye division gano a matsayin wani nau'i na mitosis, amma wasu masana kimiyya yi imani da shi shi ne mai raba inji. A hanya na wannan tsari, ko da a cikin tsohon Kwayoyin ne rare. Next za a yi la'akari meiosis da manziloli, mitosis tsari, kazalika da kamance da kuma bambance-bambance tsakanin wadannan hanyoyin. Idan aka kwatanta da sauki division su ne mafi hadaddun da nagartaccen. Wannan Gaskiya ne, saukarwa division, don haka da cewa da kasoshin lokatan meiosis halayyar ne mafi cikakken.

An muhimmiyar rawa a cell division ne centrioles - musamman wasu gabbansa, yawanci located kusa da Golgi hadaddun. Kowane tsarin kunshi microtubules 27 harhada a threes. A dukan tsarin yana da wani cylindrical siffar. A centrioles aka kai tsaye da hannu a cikin samuwar dogara sanda Kwayoyin a kan aiwatar da kai tsaye ba division, wadda za a tattauna kara.

mitosis

A tsawon lokaci na cell dabam. Wasu rayuwa kamar wata kwana, amma wasu za a iya dangana ga tsawo-rayu, saboda su cikakken canji yakan faru sosai da wuya. Kuma kusan dukkan wadannan Kwayoyin haifa via mitosis. Mafi yawansu ba su kasance tsakanin division lokacin da aka a kan talakawan 10-24 hours. Mitosis kanta bautarka karamin lokaci - a cikin dabbobi game 0.5-1 hour, da kuma shuke-shuke game da 2-3. Wannan inji tabbatar da cewa ci gaban da cell yawan jama'a da kuma haifuwa m a cikin kwayoyin cika raka'a. Saboda haka ya lura da cin gaba da al'ummomi a na farko matakin. A wannan yanayin, da yawan chromosomes kasance iri guda. Wannan inji shi ne ya fi kowa nau'i na haifuwa a eukaryotic Kwayoyin.

The darajar da irin wannan rabo ne manyan - wannan tsari ya taimaka wa girma da kuma regenerate kyallen takarda, inda a can ne a ci gaba da dukan kwayoyin. Bugu da kari, shi ne tushen mitosis sake yiwuwar tohowarsu. Kuma wani alama - da motsi na Kwayoyin da maye riga aka rabu amfani. Saboda haka, mu yi imani da cewa saboda gaskiyar cewa meiotic mataki wuya, sa'an nan da rawar ne yafi hakan ba daidai ba. Duka wadannan matakai daban-daban ayyuka da kuma a cikin su muhimmanci da kuma irreplaceable.

Mitosis kunshi dama manzilõli, iri dabam-dabam a cikin su morphological fasali. A jihar da tantanin halitta ake shirya don kai tsaye ba division, kira Interphase, da kuma aiwatar da kanta da aka raba ta 5, saukarwa, abin da ya kamata a yi la'akari da mafi daki-daki.

Da kasoshin lokatan mitosis

Duk da yake a cikin Interphase cell shirya division: kira na DNA da kuma sunadarai. Wannan mataki ne zuwa kashi da dama, a cikinsu akwai waɗansu girma daga cikin dukan tsarin da chromosome maimaitawan. A wannan jiha, tantanin halitta ya jinkirta har zuwa 90% na gaba dayan rayuwar sake zagayowar.

Sauran 10% daukan kai tsaye rabo ne zuwa kashi 5 matakai. A mitosis na shuka Kwayoyin ne ma saki Preprophase, wanda shi ne ba ya nan a duk sauran lokuta. A samuwar sabuwar Tsarin, da zuciyar da aka mayar da su cikin cibiyar. Kafa preprophase band, alama samarwa site na gaba rabo.

A yanzu wasu Kwayoyin mitosis tsari ne kamar haka:

Table 1

Bayan kammala rarraba kwayoyin bayanai cytokinesis auku ko cytokinesis. Wannan kalma tana nufin samuwar gawawwakin 'yar Kwayoyin daga uwar jiki. Kamar wancan ne da wasu gabbansa da aka kullum raba a cikin rabin, ko da yake akwai na iya zama ban, bangare ne kafa. Cytokinesis ba ware a raba lokaci, kamar yadda mai mulkin, idan akai la'akari da shi a matsayin wani ɓangare na telophase.

Saboda haka, a cikin mafi ban sha'awa matakai shafe chromosomes da cewa kawo kayyade bayani. Mẽne ne, kuma me ya sa ne da suka haka da muhimmanci?

game da chromosomes

Har ma ba tare da ciwon yar alamar ra'ayin halittar jini, mutãne sun san cewa da yawa ingancin zurriyarsu akwai dogara a kan iyayensu. Tare da ci gaban ilmin halitta, ya bayyana cewa a kan wannan ko da jiki bayanai da aka adana a cikin kowane cell, kuma wani ɓangare na shi aka wuce zuwa nan gaba.

A karshen karni na 19th shi ya gano chromosomes - Tsarin kunshi wani dogon DNA kwayoyin. Wannan ne ya sa yiwu tare da kyautata na microscopes, kuma ko da a yanzu za ka iya ganin su ne kawai a lokacin division. Mafi sau da yawa yaba da gano Bajamushe masanin kimiyya V. Fleming, wanda ba kawai shirya duk da cewa an koya kafin shi, amma kuma da gudummawar: ya kasance daya daga cikin na farko ta gudanar da bincike salula tsarin, meiosis da manziloli, kazalika da buga da Kalmar "mitosis". The sosai mas'ala ta "chromosome" da aka samarwa daga baya wasu masana kimiyya - a Jamus histologist G. Heinrich Wilhelm Gottfried von Waldeyer-Hartz.

chromosome tsarin a lokacin da su ne a fili a bayyane, shi ne quite sauki - su ne biyu chromatids aka shiga a cikin tsakiyar centromere. Yana da wani takamaiman jerin nucleotides da kuma taka muhimmiyar rawa a cikin cell yaduwa. Daga qarshe chromosome dubi prophase da metaphase, lokacin da zai iya zama mafi kyau ga, shi yayi kama da harafin H.

A shekarar 1900, an gano Mendel da dokokin, ta kwatanta da ka'idodin watsa hereditary halaye. Sa'an nan ya bayyana cewa chromosomes - wannan shi ne wani abu da wanda kwayoyin bayanai da aka canjawa wuri. A nan gaba, da masana kimiyya gudanar da wani jerin gwaje-gwajen ya tabbatar da shi. Kuma a sa'an nan ya zama batu na nazari da kuma tasiri a kan su na da buyout cell division.

meiosis

A bambanci ga wannan inji mitosis kyakkyawan take kaiwa ga samuwar biyu Kwayoyin tare da wani sa na chromosomes 2 sau karami fiye da asali. Kamar wancan aiwatar da meiosis ne lokaci miƙa mulki daga diploid zuwa haploid, a cikinsa farko muna magana ne game da nukiliya fission, kuma a karo na biyu - dukan cell. Tanadi da cikakken sa na chromosomes faruwa ne ta kara Fusion na gametes. Saboda da karu a yawan chromosomes, wannan hanya ne har yanzu bayyana a matsayin rage-cell division.

Meiosis da manziloli karatu irin shahararrun masana kimiyya a matsayin V. Fleming, E. Strasburgrer VI Belyaev da sauransu. A binciken da wannan tsari a cikin sel na biyu shuke-shuke da dabbobi, har yanzu faruwa - don haka shi ne wuya. Da farko, wannan tsari yana dauke da wani bambanci na mitosis, duk da haka, kusan nan da nan bayan bude ya har yanzu aka ware a matsayin mai raba inji. Halaye na meiosis da msar tambayar darajar da aka farko isasshe bayyana Augustus Wiseman a 1887. Tun daga nan, da nazarin na meiosis aiwatar ƙwarai cigaban, amma da binciken ba tukuna an karyata.

Meiosis ba za a rikita batun tare da jam line, ko da yake duka biyu matakai suna a hankali alaka. A samuwar jima'i Kwayoyin, duka biyu sunadaran suna da hannu, amma akwai wasu manyan bambance-bambance tsakanin su. Meiosis auku a matakai biyu na rarraba kowanne daga abin kunshi hudu main manzilõli, da gajeren hutu a tsakanin su. A tsawon lokaci da dukan tsari ya dogara da adadin DNA a tsakiya da kuma tsarin da chromosomal kungiyar. A general, shi ne yafi dogon m idan aka kwatanta da mitosis.

Ba zato ba tsammani, daya daga cikin manyan Sanadin gagarumin jinsunan bambancin - cewa meiosis. Kafa na chromosomes a sakamakon rage rabo ne zuwa kashi biyu sassa, don haka cewa akwai sabon haduwa da kwayoyin halittu, musamman yiwuwar kara da adaptability da adaptability na kwayoyin, a sakamakon samun wani sa na da halayen.

Da kasoshin lokatan meiosis

Kamar yadda aka ambata riga, da rage-cell division aka conventionally kasu kashi biyu, saukarwa. Kowace daga cikin wadannan matakai da aka raba ta 4. Kuma ko da rukunin farko na meiosis - prophase I, bi da bi, subdivided cikin 5 na daban, saukarwa. Tun da nazarin wannan tsari ya ci gaba, shi za a iya ware da kuma wasu a nan gaba. Yanzu bambanta da wadannan bulan na meiosis:

Table 2

Saboda haka, shi ne bayyananne cewa da kasoshin lokatan meiosis rabo ne yafi wuya kan aiwatar da mitosis. Amma, kamar yadda aka ambata a riga, wannan ba ya rage nazarin halittu rawar kai tsaye ba division, domin suna da daban-daban ayyuka.

Af, meiosis da manziloli an lura a wasu daga cikin sauki. Duk da haka, yawanci shi ya shafi daya kawai division. An zaci cewa wannan guda-mataki nau'i daga baya ci gaba a cikin wani zamani, biyu-mataki.

Bambance-bambance da kuma kamance tsakanin mitosis da meiosis

A duban farko alama cewa bambance-bambance tsakanin wadannan biyu matakai ne a bayyane yake, saboda su ne gaba daya daban-daban sunadaran. Duk da haka, a zurfi bincike ya nuna cewa bambance-bambance na mitosis da meiosis ba haka duniya, sun ƙarasa da kai ga samuwar sabon Kwayoyin.

Da farko wajibi ne in yi magana game da abin da yake a cikin kowa tsakanin wadannan sunadaran. A gaskiya kawai wasanni biyu: a wannan lokaci jerin, kazalika da cewa kafin division faruwa da iri DNA kwafi. Ko da yake da kamar abin da meiotic prophase Na kafin wannan tsari yana tafiya ne ba cikakke, kawo karshen kan daya daga cikin na farko substages. A jerin manzilõli, ko kama da, amma, a gaskiya, aukuwa a cikin taron ba su da cikakken daidaita. Saboda haka kama mitosis da meiosis ba haka ba ne m.

Da bambance-bambance ne mafi girma. Da farko, mitosis auku a somatic Kwayoyin, yayin da meiosis ne a hankali da alaka da samuwar gametes da sporogenesis. Da kasoshin lokatan matakai da kansu ba su da cikakken daidaita. Alal misali, mararraba-kan a mitosis ya auku a lokacin Interphase, sa'an nan ba ko da yaushe. A karo na biyu idan, duk da haka, wannan tsari yana da zuwa anaphase na meiosis. gene recombination a tsaye ba rabo ba a kullum da za'ayi, wanda ke nufin cewa shi ba ya taka wata rawa a juyin ci gaba da kwayoyin da rãyar da ciki-jinsunan bambancin. Yawan sakamakon mitotic Kwayoyin - biyu, kuma sũ, genetically m ga masu juna biyu ma'ana, kuma suna da wani diploid sa na chromosomes. A lokacin meiosis daban-daban. A sakamakon meiosis - 4 haploid Kwayoyin, abin da ya bambanta daga iyaye. Bugu da ƙari, duka biyu sunadaran bambanta da yawa a cikin tsawon, kuma shi ne alaka ba kawai ga bambanci a cikin yawan rabo matakai, amma kuma lokacin kiranka na kowane mataki. Alal misali, da farko prophase na meiosis yana tsawon yawa, saboda a wannan lokacin akwai synapsis da kuma hayewa. Wannan shi ne dalilin da ya sa shi ne kara zuwa kashi dama, saukarwa.

Overall kamance na mitosis da meiosis isasshe kananan idan aka kwatanta da su da bambance-bambance daga juna. Dame waɗannan matakai kusan ba zai yiwu. Saboda haka a yanzu ma fi mamaki cewa rage rabo ya rigaya an dauke da wani nau'i na mitosis.

A sakamakon meiosis

Kamar yadda aka ambata riga, bayan aiwatar da meiosis maimakon masu juna biyu Kwayoyin tare da wani diploid chromosome kafa hudu haploid form. Kuma idan muka yi magana game da bambance-bambance a mitosis da meiosis - wannan shi ne mafi muhimmanci. Farfadowa da na'ura na bukata lambar, a cikin hali na jam sel na faruwa bayan hadi. Saboda haka, tare da kowane sabon ƙarni ba ya faruwa, kuma ru ~ anya yawan chromosomes.

Bugu da ƙari kuma, a lokacin da meiotic recombination auku genes. A kan aiwatar da haifuwa, wannan take kaiwa zuwa gyaran ciki-jinsunan bambancin. Saboda haka da cewa ko da 'yan'uwa wani lokacin sosai daban-daban daga juna - shi ne sakamakon meiosis.

Af, da sterility na wasu hybrids a cikin dabba duniya - shi ne ma matsalar na raguwa division. Gaskiyar cewa chromosomes na iyaye na ga jinsuna daban ba zai iya shiga cikin Tasrifu ya kuma inganta, da samuwar high-sa mai yiwuwa jam sel ba zai yiwu. Saboda haka, shi ne meiosis shi ne tushen juyin raya dabbobi, tsirrai da sauran kwayoyin.