Lub cell nucleus yog nws cov organelle tseem ceeb tshaj plaws, qhov chaw khaws cia thiab luam tawm ntawm cov ntaub ntawv keeb kwm yav dhau los. Qhov no yog cov qauv membrane uas nyob ntawm 10-40% ntawm cov cell, cov haujlwm uas tseem ceeb heev rau lub neej ntawm eukaryotes. Txawm li cas los xij, txawm tias tsis muaj lub hauv paus ntawm lub nucleus, kev paub txog keeb kwm ntawm cov ntaub ntawv keeb kwm yog ua tau. Ib qho piv txwv ntawm cov txheej txheem no yog cov haujlwm tseem ceeb ntawm cov kab mob ntawm cov kab mob. Txawm li cas los xij, cov yam ntxwv ntawm cov nucleus thiab nws lub hom phiaj tseem ceeb heev rau cov kab mob ntau lub cev.
Qhov chaw ntawm lub nucleus hauv cell thiab nws cov qauv
Lub nucleus nyob rau hauv lub thickness ntawm lub cytoplasm thiab yog nyob rau hauv ncaj qha kev sib cuag nrog cov ntxhib thiab du endoplasmic reticulum. Nws yog surrounded los ntawm ob daim nyias nyias, ntawm uas yog qhov chaw perinuclear. Nyob rau hauv lub nucleus muaj ib tug matrix, chromatin thiab ib co nucleoli.
Ib txhia neeg laus hlwb tsis muaj ib tug nucleus, thaum lwm tus ua hauj lwm nyob rau hauv tej yam kev mob ntawm heev inhibition ntawm nws cov dej num. Feem ntau, cov qauv ntawm cov nucleus (lub tswv yim) yog nthuav tawm raws li kab noj hniav nuclear, txwv los ntawm karyolemma los ntawm lub xovtooj, muaj chromatin thiab nucleoli tsau hauv nucleoplasm. Nuclear matrix.
qauv ntawm karyolemma
Rau qhov yooj yim ntawm kev kawm cov nucleus cell, tom kawg yuav tsum pom tias yog npuas, txwv los ntawm cov plhaub los ntawm lwm cov npuas. Lub nucleus yog npuas nrog cov ntaub ntawv keeb kwm nyob rau hauv lub thickness ntawm lub cell. Nws yog tiv thaiv los ntawm nws cytoplasm los ntawm ib tug bilayer lipid membrane. Cov qauv ntawm lub plhaub ntawm lub nucleus zoo ib yam li cov cell membrane. Qhov tseeb, lawv tsuas yog qhov txawv ntawm lub npe thiab cov txheej txheem. Yog tsis muaj tag nrho cov no, lawv zoo tib yam hauv cov qauv thiab kev ua haujlwm.
Cov qauv ntawm karyolemma (nuclear membrane) yog ob txheej: nws muaj ob txheej lipid. Sab nrauv bilipid txheej ntawm karyolemma yog nyob rau hauv kev sib cuag ncaj qha nrog cov ntxhib reticulum ntawm lub cell endoplasm. Sab hauv karyolemma - nrog cov ntsiab lus ntawm cov nucleus. Muaj qhov chaw perinuclear nruab nrab ntawm sab nrauv thiab sab hauv karyomembrane. Thaj, nws tau tsim los ntawm electrostatic phenomena - repulsion ntawm thaj chaw ntawm glycerol residues.
Kev ua haujlwm ntawm cov ntaub so ntswg nuclear yog tsim kom muaj kev cuam tshuam kev sib txuas uas cais cov nucleus los ntawm cytoplasm. Lub puab membrane ntawm lub nucleus ua hauj lwm pab raws li ib tug fixation site rau lub nuclear matrix - ib tug saw ntawm cov protein molecules uas txhawb lub bulk qauv. Muaj cov pores tshwj xeeb hauv ob daim nyias nyias: tus xa xov RNA nkag mus rau cytoplasm los ntawm lawv mus rau ribosomes. Nyob rau hauv lub thickness ntawm lub nucleus muaj ob peb nucleoli thiab chromatin.
Cov qauv sab hauv ntawm nucleoplasm
Cov yam ntxwv ntawm cov qauv ntawm lub nucleus tso cai rau peb los sib piv nrog lub cell nws tus kheej. Nyob rau hauv lub nucleus kuj muaj ib qho chaw tshwj xeeb (nucleoplasm),sawv cev los ntawm ib tug gel-sol, ib tug colloidal tov ntawm cov proteins. Nyob rau hauv nws muaj ib tug nucleoskeleton (matrix), sawv cev los ntawm fibrillar proteins. Lub ntsiab sib txawv tsuas yog nyob rau hauv qhov tseeb hais tias feem ntau acidic proteins nyob rau hauv lub nucleus. Thaj, xws li cov tshuaj tiv thaiv ntawm ib puag ncig yog xav tau los khaws cov tshuaj lom neeg ntawm nucleic acids thiab tshwm sim ntawm biochemical tshuaj tiv thaiv.
Nucleolus
Cov qauv ntawm cov cell nucleus tsis tuaj yeem ua tiav yam tsis muaj cov nucleolus. Nws yog spiralized ribosomal RNA, uas yog nyob rau hauv lub maturation theem. Tom qab ntawd, ribosome yuav tau txais los ntawm nws - ib qho organelle tsim nyog rau kev tsim cov protein. Hauv cov qauv ntawm cov nucleolus, ob lub ntsiab lus txawv: fibrillar thiab globular. Lawv txawv ntawm electron microscopy nkaus xwb thiab tsis muaj lawv tus kheej daim nyias nyias.
Cov khoom siv fibrillar yog nyob hauv nruab nrab ntawm cov nucleolus. Nws yog ib txoj hlua ntawm ribosomal-hom RNA los ntawm cov ribosomal subunits yuav sib sau ua ke. Yog tias peb xav txog lub hauv paus (cov qauv thiab kev ua haujlwm), ces nws yog qhov pom tseeb tias cov khoom siv granular yuav tom qab tsim los ntawm lawv. Cov no yog tib yam loj hlob ribosomal subunits uas nyob rau tom qab theem ntawm lawv txoj kev loj hlob. Lawv sai sai tsim ribosomes. Lawv raug tshem tawm los ntawm nucleoplasm los ntawm cov pores nuclear ntawm karyolemma thiab nkag mus rau hauv daim nyias nyias ntawm cov tawv nqaij endoplasmic reticulum.
Chromatin thiab chromosomes
Cov qauv thiab kev ua haujlwm ntawm lub cell nucleus yog cov organically txuas: tsuas yog cov qauv uas xav tau los khaws thiab tsim cov ntaub ntawv keeb kwm yav dhau los. Kuj tseem muaj karyoskeleton(nucleus matrix), kev ua haujlwm uas yog tswj xyuas cov duab ntawm lub cev. Txawm li cas los xij, qhov tseem ceeb tshaj plaws ntawm cov nucleus yog chromatin. Cov no yog chromosomes uas ua lub luag haujlwm ntawm cov ntaub ntawv txee ntawm ntau pawg ntawm cov noob.
Chromatin yog cov protein ntau uas muaj polypeptide ntawm cov qauv quaternary txuas nrog nucleic acid (RNA lossis DNA). Chromatin kuj muaj nyob rau hauv cov kab mob plasmids. Yuav luag ib feem peb ntawm tag nrho qhov hnyav ntawm chromatin yog tsim los ntawm histones - cov proteins lub luag haujlwm rau "ntim" ntawm cov ntaub ntawv keeb kwm. Cov yam ntxwv ntawm cov qauv no yog kawm los ntawm biochemistry thiab biology. Cov qauv ntawm cov nucleus yog complex precisely vim yog chromatin thiab muaj cov txheej txheem alternating nws spiralization thiab despiralization.
Lub xub ntiag ntawm histones ua rau nws muaj peev xwm condense thiab ua kom tiav DNA strand nyob rau hauv ib qho chaw me me - hauv cell nucleus. Qhov no tshwm sim raws li nram no: histones tsim nucleosomes, uas yog ib tug qauv zoo li hlaws dai. H2B, H3, H2A thiab H4 yog cov protein ntau histone. Lub nucleosome yog tsim los ntawm plaub khub ntawm txhua qhov nthuav tawm histones. Nyob rau tib lub sijhawm, histone H1 yog qhov sib txuas: nws cuam tshuam nrog DNA ntawm qhov chaw nkag mus rau hauv nucleosome. Kev ntim DNA tshwm sim los ntawm qhov "winding" ntawm ib kab molecule nyob ib ncig ntawm 8 histone qauv proteins.
Tus qauv ntawm lub nucleus, lub tswv yim uas tau nthuav tawm saum toj no, qhia tias muaj cov qauv solenoid zoo li DNA ua tiav ntawm histones. Lub thickness ntawm no conglomerate yog hais txog 30 nm. Nyob rau tib lub sijhawm, cov qauv tuaj yeem txuas ntxiv rau hauv thiaj li yuav siv tau qhov chaw tsawg dua thiab tsis tshua pommechanical puas tsuaj uas inevitably tshwm sim thaum lub neej ntawm lub cell.
Chromatin feem
Cov qauv, qauv thiab kev ua haujlwm ntawm lub cell nucleus yog kho rau kev tswj xyuas cov txheej txheem dynamic ntawm chromatin spiralization thiab despiralization. Yog li ntawd, muaj ob feem tseem ceeb ntawm nws: muaj zog spiralized (heterochromatin) thiab me ntsis spiralized (euchromatin). Lawv raug cais ob qho tib si structurally thiab functionally. Hauv heterochromatin, DNA tiv thaiv zoo los ntawm kev cuam tshuam thiab tsis tuaj yeem muab luam tawm. Euchromatin tsis muaj kev tiv thaiv tsawg dua, tab sis cov noob tuaj yeem muab faib ua cov protein synthesis. Feem ntau, ntu ntawm heterochromatin thiab euchromatin hloov mus thoob plaws qhov ntev ntawm tag nrho cov chromosome.
YChromosomes
Lub cell nucleus, cov qauv thiab cov haujlwm uas tau piav qhia hauv tsab ntawv no, muaj cov chromosomes. Nws yog ib qho nyuaj thiab compactly ntim chromatin uas tuaj yeem pom nyob rau hauv lub teeb microscopy. Txawm li cas los xij, qhov no tsuas yog ua tau yog tias lub xov tooj ntawm tes nyob ntawm lub iav swb ntawm theem ntawm mitotic lossis meiotic division. Ib qho ntawm cov theem yog spiralization ntawm chromatin nrog kev tsim ntawm chromosomes. Lawv cov qauv yog qhov yooj yim heev: cov chromosome muaj telomere thiab ob txhais caj npab. Txhua lub cev multicellular ntawm tib hom muaj tib lub qauv ntawm lub nucleus. Nws cov chromosome teeb lub rooj kuj zoo ib yam.
Kev nqis tes ua haujlwm ntawm ntsiav tshuaj
Cov yam ntxwv tseem ceeb ntawm cov qauv ntawm cov nucleus muaj feem cuam tshuam nrog kev ua haujlwm ntawm qee yam haujlwm thiab qhov xav tau los tswj lawv. Lub nucleus plays lub luag hauj lwm ntawm lub repository ntawm hereditary ntaub ntawv, uas yog, nws yog ib yam ntawm cov ntaub ntawv txee nrogsau sequences ntawm cov amino acids ntawm tag nrho cov proteins uas yuav tsum tau synthesized nyob rau hauv lub cell. Qhov no txhais tau hais tias txhawm rau ua tiav ib qho haujlwm, lub xovtooj ntawm tes yuav tsum ua kom muaj protein ntau, cov qauv uas tau muab tso rau hauv cov noob.
Yuav kom lub nucleus "nkag siab" cov protein tshwj xeeb yuav tsum tau ua kom haum raws sijhawm, muaj cov txheej txheem ntawm sab nraud (membrane) thiab cov receptors sab hauv. Cov ntaub ntawv los ntawm lawv tuaj rau lub nucleus los ntawm molecular transmitters. Feem ntau qhov no tau pom los ntawm adenylate cyclase mechanism. Qhov no yog li cas cov tshuaj hormones (adrenaline, norepinephrine) thiab qee cov tshuaj uas muaj cov qauv hydrophilic ua rau ntawm tes.
Qhov thib ob txheej txheem ntawm kev hloov ntaub ntawv yog sab hauv. Nws yog cov yam ntxwv ntawm lipophilic molecules - corticosteroids. Cov tshuaj no nkag mus rau bilipid daim nyias nyias ntawm lub cell thiab mus rau lub nucleus, qhov twg nws cuam tshuam nrog nws cov receptor. Raws li qhov tshwm sim ntawm kev ua kom cov receptor complexes nyob rau ntawm lub cell membrane (adenylate cyclase mechanism) los yog nyob rau hauv karyolemma, cov activation cov tshuaj tiv thaiv ntawm ib tug tej yam noob tau tshwm sim. Nws replicates, ntawm nws lub hauv paus tub txib RNA yog tsim. Tom qab ntawd, raws li cov qauv ntawm yav tas los, cov protein yog synthesized uas ua tau ib qho kev ua haujlwm.
Lub nucleus ntawm ntau cov kab mob
Nyob rau hauv ib lub cev muaj ntau lub cev, cov yam ntxwv ntawm lub nucleus yog tib yam li hauv ib lub unicellular. Txawm hais tias muaj qee qhov nuances. Ua ntej, multicellularity txhais tau hais tias ib tug xov tooj ntawm cov cell yuav muaj lawv tus kheej muaj nuj nqi (los yog ob peb). Qhov no txhais tau tias qee cov noob caj noob ces yuav ib txwm muajua pa nyuaj thaum lwm tus tsis ua haujlwm.
Piv txwv li, hauv cov ntaub so ntswg adipose, protein synthesis yuav tsis ua haujlwm, thiab yog li feem ntau ntawm cov chromatin yog spiralized. Thiab hauv cov hlwb, piv txwv li, ib feem ntawm exocrine ntawm pancreas, cov txheej txheem ntawm cov protein biosynthesis txuas ntxiv mus. Yog li ntawd, lawv cov chromatin yog despiralized. Nyob rau hauv cov cheeb tsam uas nws cov noob yog replicated feem ntau. Nyob rau tib lub sij hawm, ib qho tseem ceeb feature yog ib qho tseem ceeb: lub chromosome txheej ntawm tag nrho cov hlwb ntawm ib tug kab mob yog tib yam. Tsuas yog vim muaj qhov sib txawv ntawm kev ua haujlwm hauv cov ntaub so ntswg, qee qhov ntawm lawv raug tua los ntawm kev ua haujlwm, thaum lwm tus yog despiralized ntau dua li lwm tus.
Nuclear cells ntawm lub cev
Muaj cov hlwb, cov yam ntxwv ntawm cov nucleus uas yuav tsis raug txiav txim siab, vim tias yog vim li cas ntawm lawv cov haujlwm tseem ceeb lawv tuaj yeem cuam tshuam nws txoj haujlwm lossis tshem tawm tag nrho. Qhov piv txwv yooj yim tshaj yog cov qe ntshav liab. Cov no yog cov qe ntshav, cov nucleus uas tam sim no tsuas yog nyob rau theem pib ntawm kev loj hlob, thaum hemoglobin yog synthesized. Thaum nws muaj txaus los nqa oxygen, lub nucleus raug tshem tawm ntawm lub cell kom yooj yim rau nws yam tsis muaj kev cuam tshuam nrog oxygen thauj.
Hauv cov ntsiab lus dav dav, erythrocyte yog lub hnab cytoplasmic uas muaj hemoglobin. Ib qho qauv zoo sib xws yog cov yam ntxwv ntawm cov rog rog. Cov qauv ntawm cov cell nucleus ntawm adipocytes yog qhov yooj yim heev, nws txo qis thiab hloov mus rau daim nyias nyias, thiab cov txheej txheem ntawm cov protein synthesis yog qhov ntau tshaj plaws. Cov hlwb no kuj zoo li "lub hnab" uas muaj roj, txawm tias, ntawm chav kawm, ntau yammuaj cov tshuaj biochemical me ntsis hauv lawv dua li hauv erythrocytes. Platelets kuj tsis muaj cov nucleus, tab sis lawv yuav tsum tsis txhob suav tias yog cov cell uas muaj tag nrho. Cov no yog cov seem ntawm cov hlwb tsim nyog rau kev siv cov txheej txheem hemostasis.
