Lub xovtooj yog lub tsev kawm theem pib ntawm cov kab mob nyob hauv lub ntiaj teb thiab muaj cov koom haum tshuaj lom neeg ntawm cov qauv hu ua organelles. Cov no suav nrog cov nucleolus, cov qauv thiab cov haujlwm uas peb yuav kawm hauv kab lus no.
Ntawm ntawm eukaryotic nuclei
Nuclear hlwb muaj cov kab mob uas tsis yog-membrane, denser dua karyoplasm, thiab hu ua nucleoli lossis nucleoli. Lawv tau pom nyob rau hauv lub xyoo pua 19th. Tam sim no nucleoli tau kawm tag nrho ua tsaug rau electron microscopy. Yuav luag txog thaum xyoo 50s ntawm lub xyoo pua 20th, cov haujlwm ntawm nucleoli tsis tau txiav txim siab, thiab cov kws tshawb fawb suav tias cov kab mob no, es, raws li cov dej cia ntawm cov khoom siv thaum lub sij hawm mitosis.
Kev tshawb fawb niaj hnub tau tsim tias cov organoid suav nrog granules ntawm nucleoprotein xwm. Ntxiv mus, kev sim biochemical tau lees paub tias lub cev muaj cov protein ntau. Nws yog lawv uas txiav txim siab nws qhov siab ceev. Ntxiv rau cov proteins, cov nucleolus muaj RNA thiab DNA me me.
Cell cycle
Nws yog qhov nthuav tias hauv lub neej ntawm lub xov tooj ntawm tes, uas muajLub sijhawm so (interphase) thiab kev faib tawm (meiosis - hauv kev sib deev, mitosis - hauv somatic hlwb), nucleoli tsis tau khaws cia tas mus li. Yog li ntawd, nyob rau hauv lub interphase, lub nucleus nrog lub nucleolus, uas nws lub luag hauj lwm yog preservation ntawm lub genome thiab tsim cov protein-synthesizing organelles, yuav tsum tam sim no. Thaum pib ntawm cell division, uas yog nyob rau hauv prophase, lawv ploj mus thiab rov tsim tsuas yog thaum kawg ntawm telophase, nyob rau hauv lub cell kom txog rau thaum lub tom ntej division los yog mus txog rau thaum apoptosis - nws tuag.
Nuclear organizer
Nyob rau xyoo 30s ntawm lub xyoo pua xeem, cov kws tshawb fawb pom tias kev tsim cov nucleoli yog tswj los ntawm qee ntu ntawm qee cov chromosomes. Lawv muaj cov noob uas khaws cov ntaub ntawv hais txog cov qauv thiab kev ua haujlwm ntawm nucleolus hauv cell. Muaj kev sib raug zoo ntawm tus naj npawb ntawm nucleolar organizers thiab cov organelles lawv tus kheej. Piv txwv li, tus qav clawed muaj nyob rau hauv nws karyotype ob nucleolar-forming chromosomes thiab, raws li, muaj ob nucleoli nyob rau hauv lub nuclei ntawm nws somatic hlwb.
Vim tias kev ua haujlwm ntawm nucleolus, nrog rau nws qhov muaj, muaj feem cuam tshuam nrog kev faib tawm ntawm tes thiab tsim cov ribosomes, cov organelles lawv tus kheej tsis tuaj yeem nyob rau hauv cov ntaub so ntswg tshwj xeeb hauv hlwb, ntshav, thiab tseem nyob rau hauv lub blastomeres ntawm a crushing zygote.
Nucleol Amplification
Nyob rau hauv theem hluavtaws ntawm interphase, nrog rau DNA tus kheej-duplication, muaj ntau ntau replication ntawm tus naj npawb ntawm rRNA noob. Txij li thaum lub luag haujlwm tseem ceeb ntawm nucleolus yog tsim cov ribosomes, tus naj npawb ntawm cov organelles nce siab vim yog oversynthesis ntawm DNA loci uas nqa cov ntaub ntawv hais txog RNA. Nucleoproteins tsis cuam tshuam nrogchromosomes pib ua haujlwm autonomously. Yog li ntawd, ntau nucleoli yog tsim nyob rau hauv lub nucleus, nyob deb ntawm lawv tus kheej los ntawm nucleolus-tsim chromosomes. Qhov tshwm sim no hu ua rRNA gene amplification. Txuas ntxiv mus kawm txog kev ua haujlwm ntawm nucleolus hauv lub cell, peb nco ntsoov tias lawv cov kev ua haujlwm nquag tshaj plaws tshwm sim nyob rau hauv lub sijhawm ntawm kev txo qis ntawm meiosis, vim tias qhov kev txiav txim thawj zaug oocytes tuaj yeem muaj ntau pua nucleoli.
Lub ntsiab lus tseem ceeb ntawm qhov tshwm sim no tau pom tseeb, vim tias nyob rau theem pib ntawm embryogenesis: crushing thiab blastulation, ib tug loj tus naj npawb ntawm ribosomes yuav tsum tau synthesize lub ntsiab lub tsev khoom - protein. Amplification yog ib qho txheej txheem zoo heev; nws tshwm sim hauv oogenesis ntawm cov nroj tsuag, kab, amphibians, poov xab, thiab kuj nyob rau hauv ib co protists.
Histochemical muaj pes tsawg leeg ntawm cov organelle
Cia peb txuas ntxiv kev kawm ntawm cov hlwb eukaryotic thiab lawv cov qauv, thiab xav txog cov nucleolus, cov qauv thiab cov haujlwm uas cuam tshuam. Nws yog tsim los hais tias nws muaj peb hom ntsiab:
- Nucleonema (filamentous formations). Lawv yog cov heterogeneous thiab muaj fibrils thiab lumps. Ua ib feem ntawm cov nroj tsuag thiab tsiaj hlwb, nucleonemes tsim cov chaw fibrillar. Cov qauv cytochemical thiab kev ua haujlwm ntawm nucleolus kuj nyob ntawm seb muaj cov matrix hauv nws - lub network ntawm kev txhawb nqa cov protein molecules ntawm cov qauv tertiary.
- Vacuoles (teeb pom kev).
- Granular granules (nucleolins).
Los ntawm qhov pom ntawm kev tshuaj xyuas tshuaj, cov organelle no yuav luag tag nrho ntawm RNA thiab protein, thiabDNA tsuas yog nyob ntawm nws qhov chaw ib puag ncig, tsim lub nplhaib-zoo li tus qauv - perinucleolar chromatin.
Yog li, peb tau tsim tias cov nucleolus muaj tsib qhov kev tsim: fibrillar thiab granular chaw, chromatin, protein reticulum thiab ib tug ntom fibrillar tivthaiv.
Type of nucleoli
Cov qauv biochemical ntawm cov organelles nyob ntawm hom cell uas lawv nyob, nrog rau cov yam ntxwv ntawm lawv cov metabolism. Muaj 5 lub ntsiab yam ntxwv ntawm nucleolus. Thawj - reticular, yog qhov tshwm sim tshaj plaws thiab yog tus cwj pwm los ntawm kev nplua nuj ntawm cov khoom siv ntom ntom ntom fibrillar cov khoom, lumps ntawm nucleoproteins thiab nucleone. Cov txheej txheem ntawm kev sau cov ntaub ntawv rov qab los ntawm cov koom haum nucleolar yog qhov nquag heev, yog li cov chaw fibrillar pom tsis zoo nyob rau hauv qhov kev pom ntawm lub tshuab tsom.
Txij li lub luag haujlwm tseem ceeb ntawm nucleolus hauv lub cell yog kev sib txuas ntawm ribosomal subunits, los ntawm cov protein-synthesizing organelles tsim, hom reticular ntawm lub koom haum yog muaj nyob rau hauv cov nroj tsuag thiab tsiaj. Lub nplhaib-puab hom nucleoli muaj nyob rau hauv cov ntaub so ntswg sib txuas: lymphocytes thiab endotheliocytes, nyob rau hauv uas rRNA noob yog xyaum tsis transcribed. Cov nucleoli residual tshwm sim hauv cov hlwb uas tau ploj tag nrho lub peev xwm los sau, xws li normoblasts thiab enterocytes.
Cov kab sib cais muaj nyob hauv cov hlwb uas tau ntsib kev qaug cawv nrog cov carcinogens, tshuaj tua kab mob. Thiab, thaum kawg, hom compact ntawm nucleolus yog tus cwj pwm los ntawm ntau lub chaw fibrillar thiab me me ntawmnucleonem.
YProtein nucleolar matrix
Cia peb txuas ntxiv kev kawm ntawm cov qauv sab hauv ntawm cov qauv ntawm cov nucleus thiab txiav txim siab seb lub luag haujlwm ntawm nucleolus hauv cell metabolism yog dab tsi. Nws paub tias kwv yees li 60% ntawm qhov qhuav ntawm cov organelle no suav nrog cov proteins uas tsim cov chromatin, ribosomal hais, thiab los ntawm nucleolar proteins lawv tus kheej. Cia peb nyob ntawm lawv hauv kev nthuav dav ntxiv. Qee cov proteins koom nrog hauv kev ua haujlwm - tsim cov ribosomal RNA paub tab. Cov no suav nrog RNA polymerase 1 thiab nuclease, uas tshem tawm triplets ntxiv los ntawm qhov kawg ntawm rRNA molecule. Fibrillarin protein yog nyob rau hauv lub ntom ntom fibrillar tivthaiv thiab, zoo li nuclease, nqa tawm kev ua. Lwm cov protein yog nucleolin. Ua ke nrog fibrillarin, nws muaj nyob rau hauv PFC thiab FC ntawm nucleoli thiab nyob rau hauv cov nucleolar organizers ntawm chromosomes ntawm prophase ntawm mitosis.
ib lub polypepride xws li nucleophosin yog nyob rau hauv thaj chaw granular thiab nws tau koom nrog kev tsim ntawm Ribosomes los ntawm 40 s thiab 60 s subunits.
Nucleolus ua haujlwm yog dab tsi
Kev sib txuas ntawm ribosomal RNA yog lub luag haujlwm tseem ceeb uas cov nucleolus yuav tsum ua. Lub sijhawm no, kev hloov pauv tshwm sim ntawm nws qhov chaw (xws li, hauv cov chaw fibrillar) nrog kev koom tes ntawm RNA polymerase enzyme. Ntawm no nucleolar organizer, pua pua ntawm pre-ribosomes, hu ua ribonucleoprotein globules, yog synthesized. Lawv tsim cov ribosomal subunits, uas tawm hauv karyoplasm los ntawm cov pores nuclear thiab xaus rau hauv cytoplasm ntawm lub cell. Lub 40S me subunit khi rau tus tub txib RNA thiab tsuas yog tom qab ntawd rau lawvlub 40S loj subunit txuas nrog. Ib tug laus ribosome yog tsim, muaj peev xwm nqa tawm kev txhais lus - lub synthesis ntawm cellular proteins.
Nyob hauv kab lus no, peb tau kawm txog cov qauv thiab kev ua haujlwm ntawm nucleolus hauv cov nroj tsuag thiab tsiaj txhu.
