Genetic (cytogenetic) hom kev ntsuas, nrog rau lwm tus, yog siv los txheeb xyuas cov pab pawg theem pib, txhawm rau txheeb xyuas lub xeev ntawm ib hom. Hauv kab lus no, peb yuav xav txog cov yam ntxwv ntawm cov txheej txheem, nrog rau cov teeb meem uas tus kws tshawb fawb yuav ntsib thaum siv nws.
Yim yog dab tsi
Nyob hauv cov ceg sib txawv ntawm kev tshawb fawb lom neeg, hom tsiaj tau txhais raws li nws tus kheej txoj kev. Los ntawm qhov kev xav ntawm evolutionary, peb tuaj yeem hais tias ib hom yog ib qho kev sau ntawm cov tib neeg uas muaj qhov zoo sib xws hauv cov qauv sab nraud thiab lub koom haum sab hauv, cov txheej txheem physiological thiab biochemical, muaj peev xwm ntawm kev sib tshuam tsis txwv, tawm hauv cov xeeb leej xeeb ntxwv thiab caj ces cais los ntawm cov pab pawg zoo sib xws.
Ib hom tuaj yeem sawv cev los ntawm ib lossis ob peb haiv neeg thiab, raws li, muaj tag nrho lossis cais ntau yam (thaj chaw nyob / thaj chaw dej)
Species nomenclature
Txhua hom muaj nws lub npe. Raws li cov kev cai ntawm binary nomenclature, nws muaj ob lo lus: ib tug noun thiab ib tug adjective. Lub npe yog lub npe generic, thiab adjective yog lub npe tshwj xeeb. Piv txwv li, nyob rau hauv lub npe "Dandelion officinalis", hom "officinalis" yog ib tug ntawm cov neeg sawv cev ntawm cov nroj tsuag ntawm genus "Dandelion".
Cov tib neeg ntawm cov tsiaj muaj feem xyuam hauv cov genus muaj qee qhov sib txawv ntawm qhov tsos, lub cev nqaij daim tawv, thiab kev nyiam ecological. Tab sis yog tias lawv zoo sib xws, ces lawv cov hom kev koom tes yog txiav txim siab los ntawm cov txheej txheem caj ces ntawm hom raws li kev txheeb xyuas ntawm karyotypes.
Vim li cas ib hom tsiaj xav tau
Carl Linnaeus, uas yog thawj tus muab cov npe niaj hnub no thiab piav txog ntau hom kab mob nyob, suav tias lawv tsis hloov pauv thiab tsis hloov pauv. Ntawd yog, txhua tus tib neeg sib raug rau ib hom duab ib leeg, thiab ib qho kev sib txawv ntawm nws yog qhov yuam kev hauv lub embodiment ntawm hom tswv yim.
Txij li thawj ib nrab ntawm lub xyoo pua 19th, Charles Darwin thiab nws cov thwjtim tau lees paub lub tswvyim sib txawv ntawm hom. Raws li nws, hom yog hloov pauv, heterogeneous thiab suav nrog cov ntawv hloov pauv. Qhov tsis tu ncua ntawm hom yog txheeb ze, nws nyob ntawm qhov hloov pauv ntawm ib puag ncig. Lub tsev kawm ntawv theem pib ntawm lub neej ntawm ib hom yog cov pej xeem. Nws yog qhov txawv txav thiab ua tau raws li cov txheej txheem caj ces ntawm hom.
Tau qhov kev sib txawv ntawm cov tib neeg ntawm tib hom, nws tuaj yeem nyuaj rau cov kws tshawb fawb los txiav txim siab hom kab mob lossis faib rau lawv ntawm pawg neeg.
Morphological thiab caj ces ntawm hom, biochemical, physiological, thaj chaw, ecological, cwj pwm (ethological) - tag nrho cov nocomplexes ntawm qhov sib txawv ntawm hom. Lawv txiav txim siab qhov kev cais ntawm pawg neeg, lawv cov kev sib deev tsis sib haum xeeb. Thiab lawv tuaj yeem siv los ua kom paub qhov txawv ntawm ib hom ntawm lwm tus, txhawm rau txhim kho qib ntawm lawv txoj kev sib raug zoo thiab txoj hauj lwm hauv cov kab mob lom.
Tus yam ntxwv ntawm cov txheej txheem caj ces ntawm hom
Qhov tseem ceeb ntawm qhov kev zoo no yog tias txhua tus tib neeg ntawm tib hom muaj tib lub karyotype.
A karyotype yog ib hom chromosomal "passport" ntawm ib yam kabmob, nws txiav txim siab los ntawm tus lej ntawm chromosomes tam sim no hauv cov laus somatic hlwb ntawm lub cev, lawv qhov loj thiab cov yam ntxwv:
- piv ntawm chromosome caj npab ntev;
- txoj haujlwm ntawm cov centromeres hauv lawv;
- qhov muaj qhov txwv thib ob thiab satellites.
Cov tib neeg uas muaj ntau hom tsiaj yuav tsis tuaj yeem sib txuas. Txawm hais tias nws muaj peev xwm tau txais cov xeeb ntxwv, zoo li nrog ib tug nees luav thiab nees, tsov thiab tsov ntxhuav, ces interspecific hybrids yuav tsis loj hlob. Qhov no yog vim hais tias ib nrab ntawm cov genotype tsis zoo ib yam thiab conjugation ntawm chromosomes tsis tuaj yeem tshwm sim, yog li gametes tsis tsim.
Nyob rau hauv daim duab: a mule - sterile hybrid of a luav thiab mare.
Kev kawm - karyotype
Tib neeg karyotype yog sawv cev los ntawm 46 chromosomes. Hauv ntau hom kev kawm, tus naj npawb ntawm cov DNA molecules nyob rau hauv lub nucleus uas tsim chromosomes poob nyob rau hauv thaj tsam ntawm 12-50. Tab sis muaj qhov zam. Cov txiv hmab txiv ntoo ya Drosophila muaj 8 chromosomes nyob rau hauv lub nuclei ntawm cov hlwb, thiab nyob rau hauv ib tug me me sawv cev ntawm tsev neeg Lepidoptera Lysandra, lub diploid chromosome teeb yog380.
Lub tshuab hluav taws xob micrograph ntawm condensed chromosomes, uas tso cai rau ntsuas lawv cov duab thiab qhov loj me, qhia txog karyotype. Kev tshuaj xyuas ntawm karyotype ua ib feem ntawm txoj kev tshawb fawb ntawm cov txheej txheem caj ces, nrog rau kev sib piv ntawm karyotypes nrog rau ib leeg, pab txiav txim siab hom kab mob.
Thaum ob hom yog ib qho
Qhov zoo tshaj plaws ntawm cov qauv saib yog tias lawv tsis muaj tseeb. Qhov no txhais tau hais tias kev siv tsuas yog ib qho ntawm lawv yuav tsis txaus rau kev txiav txim siab raug. Cov kab mob uas yog outwardly indistinguishable ntawm ib leeg yuav yog cov neeg sawv cev ntawm ntau hom. Ntawm no cov kev ntsuas morphological tuaj rau kev pab ntawm cov txheej txheem caj ces. Piv txwv ob:
- Hnub no, ob hom nas dub tau paub, uas yav dhau los tau txheeb pom tias yog ib qho vim yog lawv tus kheej sab nraud.
- Muaj tsawg kawg yog 15 hom yoov tshaj cum malarial uas tsuas tuaj yeem ua qhov txawv ntawm cytogenetic tsom xam.
- 17 hom kab cij pom nyob rau hauv North America uas muaj caj ces sib txawv tab sis phenotypically cuam tshuam rau tib hom.
- Nws ntseeg tau tias ntawm txhua hom noog muaj 5% ntxaib, rau kev txheeb xyuas qhov yuav tsum tau siv cov txheej txheem caj ces.
- Kev tsis meej pem nyob rau hauv lub systematics ntawm roob bovids tau raug tshem tawm ua tsaug rau karyological tsom xam. Peb hom karyotypes tau raug txheeb xyuas (2n=54 rau mouflons, 56 rau argali thiab argali, thiab 58 chromosomes rau urials).
Ib hom nas dub muaj 42 chromosomes, karyotype ntawm lwm tus sawv cev los ntawm 38 DNA molecules.
Thaum pom ib qho zoo li ob
Rau cov pab pawg uas muaj thaj tsam loj ntawm qhov ntau thiab ntau tus neeg, thaum thaj chaw sib cais ua haujlwm hauv lawv lossis cov tib neeg muaj qhov dav ecological valence, muaj cov tib neeg nrog cov karyotypes sib txawv yog yam ntxwv. Qhov tshwm sim zoo li no yog lwm qhov sib txawv ntawm kev zam hauv cov txheej txheem caj ces ntawm hom.
Piv txwv ntawm chromosomal thiab genomic polymorphism muaj ntau hauv cov ntses:
- nyob rau hauv zaj sawv trout, tus naj npawb ntawm chromosomes txawv ntawm 58 txog 64;
- ob karyomorphs, nrog 52 thiab 54 chromosomes, pom hauv Hiav Txwv Dawb herring;
- nrog cov txheej txheem diploid ntawm 50 chromosomes, cov neeg sawv cev ntawm cov neeg sib txawv ntawm cov nyiaj carp muaj 100 (tetraploids), 150 (hexaploids), 200 (octaploids) chromosomes.
Polyploid cov ntaub ntawv muaj nyob rau hauv ob qho tib si nroj tsuag (tshis willow) thiab kab (weevils). Cov nas hauv tsev thiab cov gerbils tuaj yeem muaj cov lej sib txawv ntawm cov chromosomes, tsis yog ntau yam ntawm diploid teeb.
Karyotype ntxaib
Cov neeg sawv cev ntawm cov chav sib txawv thiab hom yuav muaj karyotypes nrog tib tus lej ntawm chromosomes. Muaj ntau ntau qhov xwm txheej ntawm cov neeg sawv cev ntawm tib tsev neeg thiab cov neeg:
- Gorillas, orangutans thiab chimpanzees muaj 48-chromosome karyotype. Hauv qhov tsos, qhov sib txawv tsis tau txiav txim siab, ntawm no koj yuav tsum tau sib piv qhov kev txiav txim ntawm nucleotides.
- sib txawv me ntsis hauv karyotypes ntawm North American bison thiab European bison. Ob leeg muaj 60 chromosomes nyob rau hauv ib tug diploid teeb. Lawv yuav raug xa mus rau tib hom yog tias txheeb xyuas los ntawm cov txheej txheem caj ces.
- Piv txwv ntawm cov menyuam ntxaib caj ces kuj muaj nyob hauv cov nroj tsuag, tshwj xeeb hauv tsev neeg. Ntawm cov willowsNws tseem ua tau kom tau txais cov hybrids sib txawv.
Yuav kom nthuav tawm qhov sib txawv me me ntawm cov khoom siv caj ces hauv cov hom, nws yog ib qho tsim nyog los txiav txim siab qhov sib lawv liag ntawm cov noob thiab qhov kev txiav txim uas lawv suav nrog.
Kev cuam tshuam ntawm kev hloov pauv ntawm kev tsom xam ntawm cov txheej txheem
Tus naj npawb ntawm karyotype chromosomes tuaj yeem hloov pauv raws li qhov tshwm sim ntawm genomic mutations - aneuploidy lossis euploidy.
Thaum aneuploidy tshwm sim hauv karyotype, ib lossis ntau dua chromosomes tshwm sim, thiab tus naj npawb ntawm chromosomes kuj tseem tsawg dua li ntawm tus neeg uas muaj tag nrho. Yog vim li cas rau qhov kev ua txhaum cai no yog qhov tsis sib haum xeeb ntawm chromosomes nyob rau theem ntawm gamete tsim.
Daim duab qhia ib qho piv txwv ntawm human aneuploidy (Down syndrome).
Zygotes nrog txo tus lej ntawm chromosomes, raws li txoj cai, tsis txhob pib crushing. Thiab cov kab mob polysomic (nrog "ntxiv" chromosomes) yuav zoo siv tau. Nyob rau hauv cov ntaub ntawv ntawm trisomy (2n + 1) los yog pentasomy (2n + 3), ib tug khib tus naj npawb ntawm chromosomes yuav qhia ib qho anomaly. Tetrasomy (2n + 2) tuaj yeem ua rau muaj qhov yuam kev tiag tiag hauv kev txiav txim siab hom los ntawm cov txheej txheem caj ces.
| Mutation | Qhov tseem ceeb ntawm kev hloov pauv | Kev cuam tshuam ntawm cov txheej txheem caj ces ntawm hom |
| Tetrasomy | Ib khub ntawm chromosomes lossis ob lub chromosomes ntxiv uas tsis yog homologous muaj nyob hauv karyotype. | Thaum soj ntsuam los ntawm qhov kev ntsuas no ib leeg, cov kab mob tuaj yeem raug cais raws li muaj ib khub ntawm chromosomes ntxiv. |
| Tetraploidy | Nyob hauv karyotypemuaj plaub chromosomes los ntawm ib khub tsis yog ob. | Ib yam kab mob tuaj yeem raug xa mus rau lwm hom es tsis yog polyploid cultivar ntawm tib hom (hauv cov nroj tsuag). |
Karyotype multiplication - polyploidy - tuaj yeem ua rau tus kws tshawb fawb yuam kev thaum lub mutant karyotype yog qhov suav ntawm ntau lub diploid pawg ntawm chromosomes.
Cov Txheej Txheem Tsis Txaus Siab: Elusive DNA
Txoj kab uas hla ntawm DNA strand nyob rau hauv lub xeev untwisted yog 2 nm. Cov txheej txheem caj ces txiav txim siab txog karyotype nyob rau lub sijhawm ua ntej ntawm tes faib, thaum nyias DNA molecules pheej rov spiralize (condense) thiab sawv cev ntom ntom ntom-puab cov qauv - chromosomes. Qhov nruab nrab tuab ntawm chromosome yog 700 nm.
Lub tsev kawm ntawv thiab tsev kawm ntawv lub chaw soj nstuam feem ntau yog nruab nrog lub tshuab ntsuas qhov ntsuas qis (los ntawm 8 txog 100), nws tsis tuaj yeem pom cov ntsiab lus ntawm karyotype hauv lawv. Lub zog daws teeb meem ntawm lub teeb pom kev zoo, ntxiv rau, tso cai rau txhua qhov, txawm tias qhov kev nthuav dav siab tshaj plaws, kom pom cov khoom tsis pub tsawg tshaj li ib nrab ntawm qhov ntev ntawm lub teeb yoj luv tshaj plaws. Qhov tsawg tshaj plaws wavelength yog rau violet tsis (400 nm). Qhov no txhais tau hais tias qhov khoom me tshaj plaws pom hauv lub teeb pom kev zoo yuav yog los ntawm 200 nm.
Nws hloov tawm tias cov stained decondensed chromatin yuav zoo li huab cua, thiab cov chromosomes yuav pom yam tsis muaj cov ntsiab lus. Lub tshuab ntsuas hluav taws xob nrog qhov kev daws teeb meem ntawm 0.5 nm tso cai rau koj kom pom tseeb thiab sib piv cov karyotypes sib txawv. Xav txog qhov tuab ntawm filamentous DNA (2 nm), nws yuav ua kom pom tseeb qhov txawv ntawm cov cuab yeej zoo li no.
Cytogenetic criterion tom tsev kawm ntawv
Rau cov laj thawj tau piav qhia saum toj no, kev siv micropreparations hauv kev sim ua haujlwm raws li cov txheej txheem caj ces ntawm hom yog qhov tsis tsim nyog. Hauv kev ua haujlwm, koj tuaj yeem siv cov duab ntawm chromosomes tau txais nyob rau hauv lub tshuab ntsuas hluav taws xob. Rau qhov yooj yim ntawm kev ua hauj lwm hauv daim duab, ib tus neeg chromosomes raug muab tso rau hauv homologous khub thiab muab tso rau hauv kev txiav txim. Cov tswv yim zoo li no hu ua karyogram.
Example lab assignment
Kev Ua Haujlwm. Xav txog cov duab thaij duab ntawm karyotypes, muab piv rau lawv thiab txiav txim siab txog kev koom nrog tib neeg rau ib lossis ob hom.
Duab ntawm karyotypes rau kev sib piv lab.
Ua hauj lwm. Suav tag nrho cov chromosomes hauv txhua daim duab karyotype. Yog tias lawv phim, sib piv lawv hauv qhov tsos. Yog tias tsis yog karyogram tau nthuav tawm, nrhiav qhov luv tshaj plaws thiab ntev tshaj plaws ntawm cov chromosomes ntawm nruab nrab ntev hauv ob qho tib si duab, sib piv lawv raws li qhov loj thiab qhov chaw ntawm lub centromeres. Ua ib qho kev txiav txim siab txog qhov sib txawv / qhov sib xws ntawm karyotypes.
Teb rau txoj haujlwm:
- Yog tias tus lej, qhov loj me thiab cov duab ntawm chromosomes phim, ces ob tus neeg uas nws cov khoom siv caj ces raug nthuav tawm rau kev kawm yog tib hom.
- Yog tias tus lej ntawm chromosomes sib txawv ob zaug, thiab hauv ob daim duab muaj cov chromosomes ntawm tib qhov loj thiab cov duab, ces feem ntau cov tib neeg yog cov neeg sawv cev ntawm tib hom. Cov no yuav yog diploid thiab tetraploid karyotypes.form.
- Yog tias tus lej ntawm chromosomes tsis zoo ib yam (nws txawv ntawm ib lossis ob), tab sis feem ntau cov duab thiab qhov loj ntawm cov chromosomes ntawm ob lub karyotypes yog tib yam, peb tab tom tham txog cov qauv qub thiab mutant ntawm cov tib hom (phenomenon of aneuploidy).
- Nrog ntau tus lej ntawm chromosomes, nrog rau qhov tsis sib haum xeeb ntawm cov yam ntxwv ntawm qhov loj thiab cov duab, cov qauv yuav ua rau cov neeg nthuav tawm rau ob hom sib txawv.
Nyob rau hauv cov zis, nws yuav tsum tau qhia seb nws puas muaj peev xwm txiav txim siab hom ntawm cov tib neeg raws li genetic criterion (thiab tsuas yog nws).
Teb: Nws yog tsis yooj yim sua, txij li txhua hom kev ntsuas, suav nrog caj ces, muaj kev zam thiab tuaj yeem muab qhov yuam kev ntawm kev txiav txim siab. Qhov tseeb tsuas yog tuaj yeem lav tau los ntawm kev siv cov txheej txheem ntawm daim ntawv.
