Tshuaj nyob tus yeees ntawm chromosomes. Tus qauv, muaj nuj nqi thiab cais ntawm chromosomes

Chromosomes - nws nucleoprotein lug nyob rau hauv lub nucleus ntawm eukaryotic hlwb. Lawv khaws cia yuav luag tag nrho cov caj ces, thiab lawv yog ib cov muaj nuj nqi ntawm nws cov cia, hloov thiab ua raws li. Chromosomes yog tsis yog pom txawm nyob rau hauv lub teeb tshuab kuaj kab mob, tab sis koj muaj peev xwm kom meej meej pom nyob rau hauv lub sij hawm ntawm cell division thaum lub sij hawm mitosis thiab meiosis.

Karyotype thiab chromosomes cai

Karyotype yog lub teeb ntawm tag nrho cov chromosomes (diploid), yog nyob rau hauv ib lub tawb. Nws yog hom kev, uas yog nws mus rau txhua hom nyob beings rau lub ntiaj chaw, cov theem ntawm volatility yog tus uas tsis muaj, tab sis ib co neeg tej zaum yuav muaj tej yam nta. Piv txwv li, cov neeg sawv cev ntawm txawv kuj yog yeej zoo tib yam chromosomes (autosomes), qhov txawv nruab nrab ntawm tus karyotypes ntawm tsuas yog ib khub ntawm chromosomes - tus txiv neej pw chromosomes, los yog accessory chromosome.

Cov ntsiab lus uas chromosomes yog yooj yim: lawv tus xov tooj mus tas li (nyob rau hauv lub Somatic hlwb tej zaum yuav muaj tsuas ib tug nruj naj npawb ntawm cov chromosomes, piv txwv li, miv - 38, nyob rau hauv lub txiv hmab txiv ntoo ya Drosophila melanogaster - 8, cov nqaij qaib - 78, thiab ib tug txiv neej 46).

Chromosomes yog paired, lawv txhua tus muaj ib tug homologous khub, zoo tib yam nyob rau hauv tag nrho cov respects, xws li zoo thiab loj. Nws txawv tsuas yog tus hauv paus chiv keeb: ib - los ntawm nws tus txiv, lwm yam - los ntawm leej niam.

Homologous chromosomes yog ib tug neeg officers: txhua cov officers yog txawv los ntawm lwm tus xwb tsis nyob rau hauv tsos - lub zoo thiab loj - tab sis kuj rau qhov chaw ntawm lub teeb thiab tsaus bands.

Saab laaj - lwm txoj cai ntawm chromosomes. DNA doubles hlwb ua ntej division, uas ua rau ib tug khub ntawm tus muam chromatids. Txhua tus ntxhais cell tom qab division tau txais ib chromatid, uas yog tsim nyob rau ntawm chromosome chromosome.

qhov tseem ceeb

Chromosome, uas nws qauv yog tus yooj yim, yog tsim los ntawm DNA molecules muaj ib tug loj ntev. Nws comprises ib tug plurality ntawm linear pawg ntawm noob. Txhua chromosome muaj ib tug centromere thiab telomeres, replication pib taw tes - yog nws tsim nyog ua hauj ntsiab. Telomeres nyob rau ntawm lub tswv yim ntawm chromosomes. Vim cov neeg no thiab lub hauv paus pib ntawm replication (uas kuj hu ua pib qhov chaw), cov DNA molecule yuav replicated. Cov tib tshwm sim centromere ntawm tus muam txuas ntawm DNA mus rau lub mitotic ntxaiv division uas tso cai rau lawv kom meej disperse tus ntxhais lub hlwb thaum lub sij hawm mitosis txheej txheem.

Hais txog cov kab mob

Lub sij hawm "chromosome" yog Ameslikas npaj siab ua txoj kev xaiv lug ntse eukaryotic hlwb, tab sis zaum no nce hais kab thiab kab mob chromosome. Muaj pes tsawg leeg, zog yog zoo tib yam, yog li DE Koryakov thiab I. F. Zhimulov ntseeg tau hais tias lub tswvyim tau ntev lawm tsim nyog yuav nthuav thiab txhais tau lub chromosome yog ib tug qauv muaj ib tug nucleic acid thiab muaj ib tug cia muaj nuj nqi, kev siv thiab hloov mus rau lwm noob ntaub ntawv. Nyob rau hauv eukaryotes, chromosomes muaj nyob rau hauv lub nucleus, raws li zoo raws li plastids thiab mitochondria. Prokaryotes (non-nuclear) kuj muaj DNA, tab sis tsis nyob rau hauv lub cell nucleus. Kab mob chromosomes muaj rau hauv daim ntawv ntawm ib tug qauv ntawm RNA los yog DNA, nyob rau hauv lub capsid. Txawm li cas los ntawm lub xub ntiag nyob rau hauv lub cell nucleus ntawm cov chromosomes yog organic tshuaj, hlau ions thiab ntau lwm yam tshuaj.

Keeb kwm ntawm foundations

Zaum tau tuaj ib tug ntev txoj kev uas yuav mus ua ntej soj ntsuam chromosomes. Lawv twb xub piav nyob rau hauv cov seventies ntawm lub xeem caug xyoo: ntau yam sau phau ntawv tau hais lawv nyob hauv lawv cov khoom, cov phau ntawv thiab kev tshawb fawb cov ntaub ntawv, yog li lub foundations ntawm chromosomes yog ntaus nqi mus rau cov neeg sib txawv. Nyob rau hauv daim ntawv no lub npe I. D. Chistyakova, Alexander Schneider, O. Butschli E. Strasburger, thiab ntau lwm tus neeg, tiam sis feem ntau kws tshawb fawb pom tau hais tias 1882 raws li hauv lub xyoo ntawm lub foundations ntawm chromosomes, hu ua ib tug tho kev W. Fleming, ib tug German anatomist uas sau thiab npaj ntaub ntawv ntawm chromosomes nyob rau hauv nws phau ntawv Zellsubstanz, Kern und Zelltheilung, ntxiv mus rau lub twb uas twb muaj lawm ntaub ntawv tus kheej kev tshawb fawb. Tus heev tib lub sij hawm pom tias nyob rau hauv 1888 los ntawm Mr. Heinrich Wilhelm Gottfried von Waldeyer-Hartz histologist. Txhais chromosome txhais tau tias cia "dawb lias lub cev". Lub npe yog vim lub fact tias cov tshuaj nyob tus yeees ntawm chromosomes tso cai rau nws mus tau yooj yim khi yooj yim dyes.

Nyob rau hauv 1900, nws tau "rediscovered" Mendel tej kev cai, thiab sai sai no, tsis pub dhau ob xyoos, zaum tau xaus lus tias tus chromosomes thaum lub sij hawm meiosis thiab fertilization dab coj zoo li "hais ntawm caj" uas nws tus cwj pwm tau raws piav ua ntej lawm. Nyob rau hauv 1902, nws tus kheej ntawm txhua tus lwm yam, thiab T. Boveri W. Setton tau hypothesized tias cov chromosome qauv uas yog tseem tsis paub hais tias, muaj ib tug muaj nuj nqi mus rau kis thiab cia genetic ntaub ntawv.

Drosophila thiab noob caj noob ces

Tus thawj peb lub hlis twg ntawm lub xyoo pua xeem twb cim los ntawm cov kev sim qhia txog cov tswv yim uas cov chromosomes muaj ib caj ces lub luag hauj lwm. American zaum T. Morgan, A. Sturtevant, C. txuas hniav thiab H. Muller ua hauj lwm nyob rau hauv kev tshawb fawb, uas tau ua cov khoom thiab kev faib qauv ntawm chromosomes thiab lawv muaj nuj nqi. Sim kawm tau ua nyob rau hauv D.melanogaster, lub npe hu yog tej zaum tag nrho cov txiv hmab txiv ntoo yoov. Cov tau cov ntaub ntawv yog cov hauv paus rau lub chromosomal kev tshawb xav ntawm caj, uas yog yam txawm tam sim no, tom qab yuav luag ib puas xyoo. Raws li nws, lub chromosome txuam nrog caj ces, thiab lub noob yog laus nyob rau hauv lub linear ib theem zuj zus nyob rau hauv qhov tseeb, tab sis cov tshuaj nyob tus yeees thiab morphology ntawm cov chromosomes yog kawm los ntawm zaum nyob rau hauv peb hnub.

Rau lub chaw ua hauj lwm ntawm T. Morgan twb muab tsub lub Nobel nqi zog nyob rau hauv Physiology los yog tshuaj nyob rau hauv 1933.

Tshuaj nyob tus yeees ntawm chromosomes

Nws yuav sau ua ke hais tias cov kev tshuaj ntsuam genetic khoom nyob rau hauv lub chromosomes tshwm li nucleo-protein complex. Tom qab kev kawm tshuaj lub koom haum ntawm chromosomes nyob rau hauv eukaryotic hlwb, zaum yuav hais tias lawv muaj xws li, rau qhov cov feem ntawm lub DNA thiab cov proteins uas rau nucleo-protein complex hu ua chromatin.

Cov nqaijrog nkag mus rau nyob tus yeees ntawm chromosomes, yog ib tug tseem ceeb ib feem ntawm tag nrho cov teeb meem nyob rau hauv lub chromosomes, hais txog 65% ntawm tag nrho cov luj ntawm cov lug poob rau saum lawv. Chromosomal proteins uas muab faib mus rau hauv uas tsis yog-histone cov nqaijrog thiab histone. Histones - muaj zog puag, alkaline nyob rau hauv cov xwm lawv tshwm sim los ntawm lub xub ntiag ntawm lysine thiab argenina - qhov tseem ceeb cov amino acids.

Cov tshuaj thiab cov yam ntxwv muaj pes tsawg leeg ntawm chromosomes varied. Histones tsib tog: Hl, H2A, H2B, H3 thiab H4. Tag nrho tiam sis tus thawj feem nyob rau hauv kwv yees li sib npaug zos ntau yog muaj nyob rau hauv lub hlwb ntawm tag nrho cov hom teej tug mus rau lub siab dua cov tsiaj. Hl cov nqaijrog tsawg tshaj li ib nrab.

Synthesis of histone tshwm sim nyob rau hauv cytoplasmic polysomes. Qhov no yooj yim cov nqaijrog muaj ib tug zoo xwb, vim rau qhov uas yuav tsum tau txuas nrees nrog cov DNA molecules, thiab yog li tsis txhob muab ib nyeem uas xa tuaj nrog raws roj ntsha ntaub ntawv. Qhov no yog qhov ntxawg luag hauj lwm ntawm histones, tab sis nyob rau hauv tas li ntawd nws kuj muaj ib tug yam ntxwv muaj nuj nqi, vim uas yog muab los ntawm lub spatial lub koom haum ntawm DNA nyob rau hauv lub chromosomes.

Cov raug tshuaj nyob tus yeees ntawm interphase chromosomes thiab muaj uas tsis yog-histone cov nqaijrog, uas, nyob rau hauv lem, muab faib los ntawm ntau tshaj ib puas feem. Nyob rau hauv no series xws li enzymes lub luag hauj lwm rau lub synthesis ntawm RNA, thiab enzymes uas pib kho thiab reduplication DNA. Raws li zoo raws li yooj yim, acidic chromosomal cov nqaijrog muaj ib tug yam ntxwv thiab ntxawg muaj nuj nqi.

Txawm li cas los, cov tshuaj nyob tus yeees ntawm cov chromosome tsis xaus: ib tug muaj protein ntau thiab DNA nyob rau hauv RNA tam sim no muaj pes tsawg leeg, hlau ions, lipids thiab polysaccharides. Tej chromosomal RNA tam sim no raws li transcriptional khoom uas hais tias tau tsis tau tawm hauv lub synthesis qhov chaw.

Nyob rau hauv metaphase

Morphological nta metaphase chromosomes raws li nram no: thaum lub sij hawm thawj ib nrab ntawm mitosis lawv muaj xws li officers ntawm tus muam chromatids, uas sib thooj, nyob rau hauv lub centromere cheeb tsam (thawj constriction los yog kinetochore) - yog ib feem ntawm lub chromosome uas yog tshwm sim rau ob qho tib si chromatids. Cov tshuaj nyob tus yeees ntawm cov chromosome no kuj hloov. Qhov thib ob ib nrab ntawm mitosis yus chromatid sib cais, ua raws li los ntawm cov tsim ntawm ib leeg-tso tseg tus ntxhais chromosomes, uas yog muab faib rau tus ntxhais lub hlwb. Cov nqe lus nug ntawm yuav ua li cas npaum li cas DNA yog ib feem ntawm lub metaphase chromosomes, ntau nyob rau hauv kev ntsuam xyuas nyob rau hauv ib thiab baffled menyuam kawm ntawv. Nyob rau hauv lub xeem lub sij hawm ntawm lub interphase thiab prophase thiab metaphase chromosomes dvuhromatidny, li ntawd, lawv muab lub mis 2n4c.

kev faib ntawm chromosomes

Txoj hauj lwm ntawm lub centromere thiab qhov ntev ntawm lub caj npab, uas yog nyob rau ntawm ob sab ntawm nws cov chromosomes yog dej num raws li metacentric (L-sib npaug zos) yog hais tias tus centromere yog nyob nruab nrab thiab submetacentric (neravnoplechie) yog hais tias tus centromere yog txav mus rau ib tug thaum kawg. Tsis tas li ntawd, muaj acrocentric, los yog pas nrig-zoo li tus chromosome (centromere tau nyob yuav luag heev kawg) thiab taw tes chromosome, lub npe tis rau nws loj me me, yog li ntawd nws yog xyaum tsis yooj yim sua los mus txiav txim lawv zoo lawm. Nyob rau hauv telotsentricheskih chromosomes nyuaj heev los txiav txim seb qhov chaw ntawm cov thawj constriction qhov chaw.

compaction

Tej Somatic cell muaj 23 officers ntawm chromosomes, txhua tus uas muaj ib zaug xwb DNA molecule. Tag nrho cov ntev ntawm 46 molecules yog hais txog ob tug metres! Qhov no yog ntau tshaj li peb billion puag officers, thiab tag nrho lawv haum rau hauv ib tug ntawm tes, lub chromosomes thaum lub sij hawm interphase zoo indistinguishable txawm nyob rau hauv ib tug electron tshuab kuaj kab mob. Yog vim li cas rau qhov no - cov supramolecular lub koom haum ntawm chromosomes, los yog compaction. Nyob rau hauv txoj kev hloov mus rau ib tug sib txawv theem ntawm lub cell voj voog chromatin yuav hloov nws lub koom haum.

Tus qauv thiab tshuaj muaj pes tsawg leeg thiab qauv ntawm interphase chromosome metaphase chromosomes zaum xam tau tias yog variants li ncov qaumteb qabteb lug uas yog txuas ua ke los ntawm kev sib nrig sib hloov thaum lub sij hawm mitosis txheej txheem.

Tus thawj theem yog sawv cev los ntawm lub nucleosome compaction xov, uas tseem hu ua "cov hlaws dai nyob ntawm txoj saw". Cov yam ntxwv ntawm tus loj - 10-11 nm, uas tsis pub kom xav txog lawv nyob rau hauv ib tug tshuab kuaj kab mob.

Tshuaj nyob tus yeees ntawm chromosomes txiav txim hauv lub xub ntiag ntawm no theem ntawm lub koom haum: nws muab plaub hom histones - cov tub ntxhais cov nqaijrog (H2A, H2B, NC, N4). Lawv tsim ib tug ua kiav txhab - lub cev ntawm cov protein molecules zoo li tus txuas. Txhua kiav txhab muaj yim molecules (vapor molecules los ntawm txhua histones).
Tshwm Sim DNA los ua ke, nws yog spirally txhab rau cov tawv ntoo. Nrog tiv tauj lub cev ya protein DNA molecule muaj 146 nucleotide officers. Muaj tsis koom nyob rau hauv kev sib cuag cheeb tsam, hu ua Linker, los yog binders. Lawv loj mas nws txawv, tab sis qhov nruab nrab yog 60 officers ntawm nucleotides (n. N.).

Hu nucleosome DNA cheeb tsam muaj ib ntev ntawm 196 BP thiab muaj xws li protein cortex. Txawm li cas los nucleosome filament xov zoo li cov hlaws dai, thiab ib thaj av tsis muaj lub cortex.

Tej feem uas paub qhov txawv txig uas tsis yog-histone cov nqaijrog, vim lub xub ntiag ntawm kev nucleotide sequences yog heev uniformly ntawm ua mib ntawm ib tug ob peb txhiab puag officers. Lawv muaj yog ib qho tseem ceeb rau lub ntxiv compaction ntawm chromatin.

Ntxiv cov ntawm chromatin

Chromatin fibril - compaction thib ob theem - kuj hu ua ib tug solenoid, los yog nukleomernym theem. Loj yog 30 nm. Muab histone HI. Nws teams nrog ib tug Linker DNA ib theem zuj zus, raws li zoo li nrog ob tug nyob sib ze crusts thiab "cia li nkaum kiag" lawv ua ke. Cov tshwm sim ntawm cov txheej txheem yuav ntau npaum li cas compact qauv, li tus qauv ntawm ib solenoid. Tej fibril, nyob rau hauv tas li ntawd mus rau lub chromatin yog hu ua elementary.

Raws li hronomerny theem. Cov yam ntxwv ntawm tus luaj li cas ntawm cov theem ntawm compaction - 300 nm. Twb yog tsis muaj ntxiv helix tsim, tab sis ua tus ntoo khaub lig hinges uas coincide nrog qhov luaj li cas ntawm ib replicon thiab cov chav los ntawm txoj kev uas tsis yog-histone (acidic)

Nyob rau hromonemnom theem (700 nm) ntawm lub voj sib, thiab txawm ntau kompaktiziruetsya chromatin. Educated strands ntawm chromosomes twb pom nyob rau hauv lub teeb tshuab kuaj kab mob.

Chromosomal txheej (1400 nm) yog cai thaum lub sij hawm metaphase.

Change thiab lawv lub luag hauj lwm nyob rau hauv cov tshuaj

Cov kev hloov ntawm chromosomes - tsis yooj yim dua, tab sis tej zaum yuav muaj ib tug txawv degree thiab mechanisms ntawm. Cov kev hloov nyob rau hauv lub yam ntxwv daim ntawv ntawm chromosomes yog feem ntau raws li nyob rau hauv thawj zaug breakage. Yog hais tias muaj yog so nyob rau hauv lub chromosome, ces lub cev muaj tsim lawv restructuring, nrog rau cov tshwm sim hais tias muaj yog ib tug chromosomal hloov los yog aberration.

Thaum lub sij hawm lub crossover homologous chromosomes pauv cov chaw, thiab nws lov feem ntau tshwm sim nyob rau lub sij hawm no. Yog hais tias, thaum lub sij hawm ib tug pauv ntawm teej hla dhau feem ntawm lub noob, tshiab linkage pawg.

hom change

Muaj ob peb hom change raws li nyob rau hauv lub mechanism ntawm keeb kwm. Hloov ntawm fission tshwm vim tsis noob feem. Yog hais tias ib co qhov chaw ntawm lub genome tau ob npaug - qhov no Individuals. Thaum lub sij hawm inversion ntawm lub chromosome ntawm lub discontinuities feem yog rotated los ntawm 180 °.

Translocation hu ua txoj kev hloov cheeb tsam los ntawm ib tug chromosome mus rau lwm lub, thiab yog hais tias lub xaav tshwm sim ntawm uas tsis yog-homologous chromosomes, hu ua reciprocal translocation, thiab yog hais tias tus fragment tau koom nrog cov tib chromosome hloov hu ua transposition. Thaum lub sij hawm Robertsonian translocation tshwm sim unification rau hauv ib tug ntawm ob tug uas tsis yog-homologous lug.

Tseem muaj change pericentric thiab paracentric.

RNA

Nyob rau hauv lub theem nyob rau hauv uas lub cell, hloov cov tshuaj muaj pes tsawg leeg, morphology, yam ntxwv thiab luaj li cas ntawm cov chromosomes, tab sis lub caj khoom muaj tsis tau tsuas yog cov DNA thiab chromosomes nyob rau hauv lub nucleus.

Ribonucleic acid (RNA) - lwm qauv koom nyob rau hauv lub hloov lwm lub tsev thiab cia ntawm kev tshuaj ntsuam genetic ntaub ntawv.

Muaj mRNA los yog mRNA (matrix, los yog ntaub ntawv), nws koom nyob rau hauv lub synthesis ntawm cov nqaijrog nrog xav zog. Rau qhov no nws yog tsim nyog tias qhov chaw ntawm "kev tsim kho" tau txais "cov lus qhia", uas yuav qhia qhov kev txiav txim nyob rau hauv uas amino acids yog yuav tsum tau muaj nyob rau hauv lub peptide saw. Qhov no qhia ntaub ntawv yog kho nyob rau hauv lub nucleotide ib theem zuj zus ntawm lub mRNA (mRNA). Transcription thiab yog hu ua tub txib RNA synthesis.

Tus txheej txheem ntawm kev nyeem ntawv cov ntaub ntawv los ntawm DNA yuav muab piv nrog rau cov computer program. Thawj RNA polymerase promoter yuav tsum ntes - ib tug tshwj xeeb feem ntawm cov DNA molecule, uas marks pib ntawm lub transcription cheeb tsam. RNA polymerase uake mus rau lub promoter thiab pib unwinding uas nyob ib sab tig-helix DNA. Thaum no tus taw tes, ob strands ntawm DNA yog kaw los ntawm txhua lwm yam, whereupon lub enzyme mRNA tsim pib rau ib tug ntawm lawv (kodogennoy txojkev enzyme 3`-end). Ribonucleotides sau nyob rau hauv cov saw txoj cai ntawm complementarity mus rau lub nucleotides ntawm DNA thiab antiparallel nrog hwm rau template DNA strand.

Tus txheej txheem ntawm transcription

Yog li, thaum peb txav mus raws DNA txoj saw, qhov enzyme yog nyeem tag nrho cov ntaub ntawv, txuas ntxiv rau txoj kev kom txog thaum nws muaj raws li ib qho kev tshwj xeeb ntawm nucleotides. Nws yog hu ua tus terminator ntawm kev sau ntawv, thiab cov cim qhia tias RNA polymerase yuav tsum tau cais los ntawm ob qho tib si DNA template strand thiab cov tshiab synthesized mRNA. Tus lej ntawm cov cheeb tsam los ntawm tus neeg txhawb nqa mus rau lub chaw xaus, nrog rau cheeb tsam transcribed, yog hu ua chav hloov tsev - transcripton.

Raws li RNA polymerase txav raws coding saw, cov transcribed ib cheeb tsam DNA cais tau rov ua ke dua thiab siv daim ntawv thib ob. Cov mRNA uas tsim muaj qhov tseeb ntawm cov ntaub ntawv theej tawm los ntawm DNA qhov chaw. Nucleotides ntawm mRNA encoding amino acid sequences yog pawg hauv peb thiab hu ua codons. Txhua lub codon ntawm mRNA sib raug mus rau ib hom kev amino acid.

Noob zog thiab kev ua haujlwm

Tus gene no yog ib qho kev ua haujlwm nyob rau hauv tsev kawm ntawv qib qis. Nws muaj cov tsos ntawm ib feem ntawm DNA tus kabmob, uas ua rau cov qauv ntawm yam tsawg ib peptide.

Cov noob muaj tej yam khoom, thawj qhov uas yog qhov xwm txheej ntawm qhov kev txiav txim. Qhov no txhais tau hais tias ntau tus neeg laus cov noob tswj kev txhim kho ntawm tus yam ntxwv ntawm tus neeg.
Cov cuab yeej ntawm constancy yog txiav txim siab los ntawm qhov tseeb tias cov noob no tsis muaj zog ntawm kev sib kis ntawm kev sib kis, tshwj tsis yog tias, tau hloov. Nws ua raws li hais tias cov noob tsis tuaj yeem hloov tsis tau thaum lub neej.

Qhov tseem ceeb ntawm qhov kev txiav txim siab yog nyob rau hauv kev tsis txaus siab ntawm kev tsim ntawm qhov kev zoo los yog pab pawg ntawm cov nta, tiam sis cov noob kuj muaj peev xwm ntau yam - qhov no hu ua pleiotropy.

Cov khoom ntawm qhov kev txiav txim ntawm qhov kev txiav txim tau txiav txim siab qhov txwv uas tus kos npe rau ntawm cov noob tau tsim.

Lawv kuj yog cov uas tau los ntawm ib lub xeev allelic, uas yog, yuav luag tag nrho cov genes nyob hauv alleles, cov xov tooj uas pib nrog ob.