Me nyuam muaj nuj nqi thiab lom tseem ceeb ntawm meiosis

Cov me nyuam muaj nuj nqi ntawm lub cev yog nqa tawm thaum lub sij hawm kev twb kev txuas ntawm ob gametes (kab hlwb) nyob rau hauv cov kev tshwm sim thiab lub tom ntej txoj kev loj hlob ntawm lub zygote subsidiary lub cev - fertilized qe. Nyob rau hauv kev sib deev niam txiv hlwb muaj ib yam txheej n-chromosomes. Nws hu ua haploid. Zygote yog noj ib txheej ntawm cov no, nws yog ib tug diploid ntawm tes, xws li, chromosome tooj 2n muaj: ib tug niam thiab ib tug txiv. Lom meiotic division tshwj xeeb tseem ceeb raws li nyob rau hauv lub cell muaj nyob rau hauv lub fact tias ua tsaug rau nws, tus haploid cell tsim los ntawm cov diploid hlwb.

txhais

Meiosis hauv ib yog hu ua ib tug zoo ntawm mitosis; vim nws diploid Somatic hlwb ntawm lub qhov chaw mos qog raug muab faib ua 1n gametes. Thaum lub noob pob kws yog fertilized, muaj yog ib tug fusion ntawm gametes. Yog li, nws yog recovering 2n chromosome teeb. Lub ntsiab lus ntawm meiosis yog los xyuas kom meej preservation ntawm lub xam qhovkev txhua yam uas muaj sia nyob chromosomes thiab ib tug tsim nyog kom muaj nuj nqis ntawm DNA.

piav qhia

Meiosis - tus txheej txheem yog tas mus li. Nws muaj ob hom ntawm faib successively nram qab no txhua lwm yam: meiosis kuv thiab meiosis II. Txhua yam ntawm cov txheej txheem, nyob rau hauv lem, muaj prophase, metaphase, anaphase, telophase. Tus thawj division ntawm meiosis los yog meiosis kuv, halves tus xov tooj ntawm chromosomes, i.e. muaj yog lub phenomenon ntawm lub thiaj li hu ua yuav txo tau faib. Thaum nws yog tus thib ob theem ntawm meiosis los yog meiosis II, haploid hlwb tsis hem qhov kev hloov, nws yeej dim lawm. Qhov no yog hu ua equational division.

Tag nrho cov hlwb nyob rau hauv cov theem ntawm meiosis, nqa ib co lus qhia rau cov kev tshuaj ntsuam genetic theem.

• Meiotic prophase ntawm thawj - theem hnyav helix chromatin thiab tsim ntawm chromosomes. Thaum kawg ntawm qhov kev heev txiav txim lub caj khoom tam sim no nyob rau hauv nws thawj daim ntawv - 2n2 chromosomes.
• Metaphase los - los thiab cov qib siab tshaj plaws ntawm helix. Cov kev tshuaj ntsuam genetic khoom yog tseem tsis tau hloov.
• Anaphase ntawm meiosis yog nrog los ntawm ib tug txo. Txhua khub niam txiv chromosomes muab ib qho ntawm nws tus ntxhais lub hlwb. Caj khoom hloov nyob rau hauv muaj pes tsawg leeg, raws li chromosome tooj yog ib nrab tias: rau txhua tus ncej ntawm lub cell yog tsim nyog rau 1n2 chromosome.
• Telophase - theem thaum txoj kev ua rau cov tub ntxhais, sib cais cytoplasm. Ntxhais hlwb yog tsim, lawv yog 2 thiab txhua tus ntawm ob chromatids. Xws li teem ntawm chromosomes nyob rau hauv lub haploid lawv.
• Ntxiv interkinesis cai, ib tug luv luv so ntawm tus thawj thiab thib ob theem ntawm meiosis. Lub ob tus ntxhais lub hlwb yog npaj txhij mus rau hauv lub thib ob theem ntawm meiosis, uas tshwm sim los ntawm tib lub mechanism li hais tias ntawm mitosis.

Lub lom tseem ceeb ntawm meiosis yog li ntawd nyob rau hauv lub fact tias nyob rau hauv nws cov kauj ruam thib ob los ntawm complex mechanisms twb tsim haploid hlwb 4 - 1n1 chromosomes. Xws li, ib tug diploid niam cell muab lub neej mus rau plaub - txhua haploid chromosome teeb. Nyob rau hauv ib yam ntawm cov thawj meiotic degree theem kev tshuaj ntsuam genetic khoom recombines, thiab cov kauj ruam thib ob yog nqa tawm zog ntawm chromosomes thiab chromatids mus txawv ncej ntawm lub cell. Cov kev taw - qhov ntawm variation thiab txawv ob peb ua ke ntawm intraspecific.

tau

Yog li, lom tseem ceeb ntawm meiosis, yeej zoo kawg thiab. Ua ntej ntawm tag nrho cov, nws yuav tsum tau muab sau tseg raws li lub ntsiab, lub ntsiab theem ntawm lub genesis ntawm gametes. Meiosis ensured hloov lwm lub tsev ntawm kev tshuaj ntsuam genetic ntaub ntawv los ntawm ib tug kab mob hom mus rau lwm lub, muab hais tias lawv cov me nyuam kev sib deev los ntawm. Meiosis enables intraspecific ob peb ua ke tshwm sim vim hais tias tus ntxhais lub hlwb txawv tsis tsuas yog los ntawm cov niam txiv, tiam sis kuj txawv.

Nyob rau hauv tas li ntawd, cov lom tseem ceeb ntawm meiosis muaj nyob rau hauv muab kev pab txo tus naj npawb ntawm chromosomes nyob rau hauv lub caij thaum cov kab hlwb yog tsim. Meiosis kom lawv haploid; thaum lub sij hawm ntawm lub fertilization lub zygote diploid chromosome qauv yog rov qab los.