YADROI HUJAYRA

YAdro qismi tarkibii hujayra buda, dar on KDN, yane genho joy dorand. YAdro du vazifai muhimro ijro mekunad:

1- nigohdoranda va takrorkunandai akhboroti irsi; 2 – tanzimkunandai ravandhoi mubodilai moddahoe, ki dar hujayra meguzarand. Hujayra be yadro duru daroz zindagi karda nametavonad. Hamchunin, yadro niz ozodona qobiliyati zist nadorad, baroi hamin yadro va sitoplazma ba ham zich aloqamand buda, sistemai tomro tashkil mekunand. Beshtari hujayraho doroi yak yadroand. Lekin hujayrahoe niz hastand, ki 2-3 yadro dorand, masalan, hujayrahoi jigar. Hamchunin, hujayrahoe vomekhurand, ki seryadroand va adadi yadroi onho to dahho merasand.

SHakli yadro bo shakli hujayra vobastagi doshta, metavonad beshakl niz boshad .

YAdroho doirashakl va serqanot meshavand. Nohamvori va hubobchahoi pardai yadro to andozae sathi yadroro ziyod mekunad, ki in ba afzoishi aloqai sokhtorhoi yadroi va sitoplazmavi musoidat menamoyad (rasmi 5.5).

Sokhti yadro. YAdro bo parda pushida shuda, az du qabat membrana iborat ast (rasmi 5.6). Membranai qabati berunii yadro bo sitoplazma nigaronida shuda, bo ribosomaho pushida shudaast. Membranai daruni hamvor ast. Pardai yadroqismi sistemai membranavii hujayraro tashkil mekunad. Gurichahoi membranai beruni yadro bo juyakchahoi turi endoplazmavi payvast shuda, yak sistemai bo ham aloqamandi juyakchahoro tashkil medihad. Mubodilai moddaho dar bayni yadro va sitoplazma bo du roh amali megardad. YAkum, dar pardai yadro masomahoi khurd bisyor buda, ba vositai onho mubodilai molekulaho bayni yadro va sitoplazma barguzor megardad.

Duyum, in moddaho az yadro ba sitoplazma va baraks, dar natijai pechishho meguzarand (ba rasmi 5.5 nigared). Garchande mubodilai moddaho bayni yadro va sitoplazma faol ast, lekin pardai yadro qobiliyat dorad, ki mahsuli khudro az sitoplazma judo namoyad. Dar natija farqiyati tarkibi khimiyavii shirai yadro az sitoplazma nigoh doshta meshavad. In baroi faoliyati mutadili sokhtorhoi yadro lozim ast.

Muhtavoi yadro az shirai yadro, khromatin va yadrocha iborat ast. Dar hujayrai zinda shirai yadro moei beshakl buda, dar tarkibi on safedahoi gunogun, az jumla, fermenthoi yadro, safedahoi khromatini va safedahoi ribosomaho joy

giriftaand. Dar shirai yadro hamchunin nukleotidhoi ozod, baroi sokhtori KDN va KRN aminokislotaho, hamai namudhoi KRN va mahsuli faoliyati yadro va khromatin, ki bazan bo sitoplazma meguzarad, mavjudand.

Hromatin (az lotinii chromo – rang) gufta, sokhti panjarashakli yadroro menomand, ki ba osoni rang megirad va bo shakli khud az yadrocha farq mekunad. Hromatin dar tarkibi khud KDN va safeda doshta, qismi khromosoma ast va dar shakli pechutob namoyon meshavad. Qismhoi morpechi khromosoma az jihati genetiki gayrifaoland.

Hromosomaho vazifai asosii khudro, ki guzaronidani akhboroti irsi ast, faqat dar holati despiralizatsiya ba jo meorand. Dar hujayrahoi taqsimshavanda hamai khromosomaho shakli spirali (purpechutob) dorand.

Hromosoma sokhtori mustaqili yadro ast. SHakli khromosoma ba kashishkhuraki yakumin vobasta buda, onro sentro mera menomand; dar vaqti taqsimshavii hujayra (mitoz) ba on tori akhromatini payvast megardad. Sentromera khromosomaro ba du kitf (dush) judo mekunad. Vobasta ba joygirii sentromera khromosomaho se shakl meshavand:

1. Barobardush, ki hardu jonibi dushi khromosoma barobarand yo qarib barobarand;
2. Nobarobardush, yane darozii dushho nobarobarand;
3. CHubchamonand, ki yak dush daroz, dushi digar khurd buda, bazan bo mushkili namoyon megardad.

Hamchunin, khromosomahoi nuqtashaklro niz didan mumkin ast, ki dushho khele khurdand (rasmi 5.15).

Dar natijai omuzishi khromosomaho malum gasht:

1. Dar hamai hujayrahoi jismi rastani va hayvonot miqdori khromosomaho yakkhelaand.
2. Hujayrahoi jinsii rastani va hayvonot nisbat ba hujayrahoi jismi du marotiba kamtar khromosoma dorand.
3. Miqdori khromosomahoi hujayrai organizmhoe, ki ba yak namud dokhil meshavand, yakkhelaand.

Miqdri khromosomaho nishonai darajai tashakkul nabu- da, hamesha qarobati organizmhoro muayyan namekunand. Bazan dar guruhhoi sistematikii az ham dur miqdori yakkhelai khromosomahoro didan mumkin ast, yo baraks namudhoi qarobatashon nazdik miqdori gunoguni khromosoma dorand. meravad, yane ba har namudi rastani va hayvonot dastai muayyani khromo-

somaho khos ast. Umumiyati miqdori va sifatii alomathoi dastai khromosomahoi hujayrahoi jismii in yo on namudi organizmhoro kariotip menomand (rasmi 5.16).

Miqdori khromosomaho dar kariotipi aksariyati namudho juftand. In daleli on ast, ki dar hujayrahoi jismi du khromosomai shakl va andozai yakkhela dorad va yake az organizmi padar va digare az modar meros girifta shudaast. Hromoso-

mahoi shaklu andozaashon yakkhela genhoi bo ham monand dorand va onhoro khromosomahoi gomologi menomand.

Dastai khromosomai hujayrai jismi, ki har yaki on jufti khudro dorad, dutoi yo diploidi buda, bo 2p ishora meshavad.

Hamin tariq, miqdori KDN ba dastai khromosomahoi diploidi muvofiq buda, bo 2s ishora megardad. Az har jufti khromosomahoi gomologi ba hujayrahoi jinsi faqat yakto meguzarad. Az in ru, dastai khromosomai (gametaho) hujayrahoi jinsi yaktoi yo gaploidi (toq) nomida shuda, kariotipi chunin hujayrahoro bo 1p, 1s ishora menamoyand.

Badi ba anjom rasidani taqsimshavii hujayra, khromosomaho rost shuda, shakli tormonandro megirand va dar yadroi hujayrahoi dukhtarona paydo gashta, tori borik va lundai khromatin az nav ba vujud meoyad.

YAdrocha. YAdrocha yake az qismhoi yadro buda, shakli doiraro dorad va dar shirai yadro joygir shudaast (ba rasmi 5.5 nigared). Dar yadroi hujayrahoi gunogun, hamchunin dar yak khudi hujayra vobasta ba vazifa az 1 to 5-7 va beshtar yadrocha mavjud ast. Miqdori yadrochaho metavonand az miqdori dastai khromosoma niz ziyodtar boshad. In dar natijai duchandshavii intikhobii genhoe, ki baroi sintezi KRN-r lozimand, ba amal meoyad. YAdrocha faqat dar yadrohoi taqsimnashuda vujud dorad; dar vaqti taqsimshavii mitozi yadrocha dar natijai pechutob khurdani khromosomaho nest meshavad. Badi ba okhir rasidani taqsimshavi, yadrochaho boz az

nav ba hamon miqdori peshina tashakkul meyoband. YAdrocha sokhtori mustaqili yadro nabuda, dar atrofii khromosoma, ki dar on jo genhoi sokhtori KRN-r (rasmi 5.17) joygirand, tashakkul meyobad. In qismi khromosoma (gen) tash-kilkunandai yadrocha nom doshta, dar on jo sintezi KRN-r ba amal meoyad. Fayr az jamshavii KRN-r dar yadrocha hissa-chahoi ribosoma ba vujud omada, ba sitoplazma meguzarad.

Bo yorii kationi Sa2+ ribosomaho tom shuda, qobiliyat dorand dar sintezi safeda ishtirok kunand. Hamin tavr, yadrocha mavzei jamshavii KRN-r va ribosomaho buda, asosi onro qismi khromosoma, ki geni tashkilkunandai yadrochahoro dorad, tashkil medihad (dar on akhboroti irsi oid ba sokhtori KRN-r joy giriftaast).

Savolho baroi sanjish:

1. Sokhti yadroi hujayrai eukariotiro fahmoned.
2. YAdrocha chist?
3. Mubodilai moddaho dar bayni yadro va sitoplazma chi guna meguzarad?
4. Hromatin chist?
5. Hromosomaho chi guna va az chi sokhta shudaand?
6. Tanosubi miqdorii khromosomahoi jismi va jinsi chigunaand?
7. Kadom khromosomahoro gomologi menomand?
8. Kariotip chist? Onro sharh dihed.
9. Kadom dastai khromosomahoro gaploidi va diploidi menomand?
10. Hromosomai bakteriyahoro ba yod ovarda, farqiyati onro az khromosomai eukariot nishon dihed.

Istilohot:

1. YAdrocha – jam shudani safedahoi KRN-r va qismhoi ribosoma. Asosi onhoro qismi khromosoma, ki dar on geni tashkilkunandai yadrocha voqe ast, muayyan mekunad.
2. Kariotip – jambasti alomathoi sifati va miqdorii dastai khromosomahoi hujayrai jismi.

3. Hromosoma – strukturai mustaqili yadro, ki dushho va sentromera doshta, az du khromatin iborat ast.
4. Geterokhromatin – granulho va turi sokhtorii yadroi taqsimshudai hujayra, ki to andozae qismi khromosomai on shakli spiralro dorad.
5. Pardai yadrogi – strukturai hujayra, ki az du membrana iborat buda, yadroro az sitoplazma judo mekunad.
6. Eukhromatin – qismi faoli genetikii khromosoma, ki dar zeri mikroskopi rushnoi dida nameshavad.
7. Karioplazma – holati makhsusi yadro, ki dar on mahluli mavodi faoliyati hayoti sokhtori yadrogi joy giriftaast.