Bangaki-chromosomes e abantu?

Chromosome - elementi kwesakhiwo futhi functional we kuyi-nucleus yengqamuzana, ehlanganisa ezakhini zofuzo. Igama elithi "chromosome" lisuselwa emagameni ngesiGreki (chrōma - coloration nombala Soma - umzimba), futhi ngenxa yokuthi lokho ngesikhathi cell division, baba ngokujulile namabala ebukhoneni udayi eyisisekelo (isib aniline).

Ososayensi abaningi, kusukela ekuqaleni kwekhulu XX, bacabanga ngalo mbuzo: ". Ama-chromosomes e Bangaki e abantu" Ngakho kuze 1955 zonke "izingqondo" babeqiniseka ukuthi inani lezakhi zofuzo kubantu 48, okungukuthi, 24 ngazimbili. Isizathu kwaba ukuthi Teofilus Peynter (Texas isazi) ngephutha wabathola e testis izigaba preparative zabantu ababekwa wawungabavumeli isinqumo senkantolo (ngo-1921). Esikhathini esizayo, abanye ososayensi besebenzisa izindlela zokulinganisa ezahlukene, futhi nize kule umbono. Ngisho basungula indlela zokwehlukanisa-chromosome, abacwaningi akazange inselelo umphumela Painter. Ososayensi baye bathola ukuthi iphutha Albert Levan futhi Joe Hin Tyo ngo-1955 ukuthi abalwa ngokunembile, indlela ngazimbili eziningi lezakhi zofuzo kubantu, okungukuthi - 23 (uma ukubala wasebenzisa ubuchwepheshe besimanje ngaphezulu).

Ukuphathwa kwabathintwayo futhi germ cells aqukethe ahlukene Ama-chromosomes e ezitshalweni zohlobo, esingenakubalwa wathi mayelana nezici morphological-chromosomes, okuyizinto njalo. amaseli ukuphathwa kwabathintwayo kuthiwa kabili (diploid) okuyinto ihlukaniswe yebhangqa ezifanayo (homologous) Ama-chromosomes e afana e morphology (isakhiwo) nokubaluleka. Omunye ingxenye njalo omunye kayise - imvelaphi kwabakhulelwe. amaseli zangasese wesintu owodwa (gametes) kukhona haploid (owodwa) iqoqo chromosome. Uma kokukhulelwa isifika ndawonye kwelinye zygote nucleus amasethi haploid besilisa gametes zesifazane. Lokhu kusibuyisela isethi double. Kungenzeka ukuba ngokuqiniseka bangaki Ama-chromosomes e umuntu - 46, 22 namabhuzu autosomes nokukodwa pair of olulodwa - ucansi-chromosomes (allosome). Ubulili Ukwehluka - kokubili morphological takhi (ukwakheka izakhi zofuzo). Ngo umzimba female yakhiwa pair gonosom X chromosome amabii (XX-pair), futhi iduna - omunye X- futhi Y-chromosome (XY-Pair).

Morphologically, ama-chromosome washintshwa phakathi cell division, basuke kabili (ngaphandle lwegciwane amaseli lapho kabili kwenzeka). Lokhu kaningi, kodwa ushintsho isethi chromosome is hhayi waphawula. I-chromosome ephawuleka kakhulu kwelinye izigaba cell division (metaphase). Kulesigaba-chromosome emelelwa zokwakheka ezimbili longitudinally uhlukanise (udade chromatids), okuyinto taper futhi ehlangana okubizwa ngokuthi constriction eyinhloko noma tsenromery (chromosome isici esihlala). telomere ebizwa le-chromosome kuphelile. Ikhipha chromosome ethulwa DNA (deoxyribonucleic acid) okuyinto buqonda izakhi zofuzo kufakwe Ukwakheka kwabo. Zofuzo, esikhundleni salokho, ukunikeza ulwazi mayelana noma yisiphi isibonakaliso esithile.

Bangaki-chromosomes e umuntu kuzoncika ukuthuthukiswa bakhe ngabanye. Kunezinto ezifana aneuploidy (ushintsho inani lezakhi zofuzo umuntu) kanye polyploidy (inombolo amasethi haploid ezingaphezu kuka diploid). Lesi sakamuva ngezinhlobo eziningi: ukulahlekelwa wama-chromosomes homologous (monosomy) noma ukubukeka Ama-chromosomes e extra (trisomy - omunye xaxa, tetrasomiya - esengeziwe ezimbili, njll). Konke lokhu is phetho ocwaningweni kanye chromosomal ukuguquka kwezakhi zofuzo, okungaholela izimo zokucabanga okubangelwa isifo ezifana: -Down syndrome, Klinefelter syndrome, Turner Shereshevkogo kanye nezinye izifo.

Ngakho, nguye kuphela ngekhulu leminyaka lamashumi amabili wanika izimpendulo zayo yonke imibuzo, manje bangaki-chromosomes umuntu uyazi zonke izakhamuzi elifundile iplanethi enguMhlaba. Kuyinto kulokho kuyoba indlela yokwakheka ngazimbili 23 wama-chromosomes (XX noma XY), incike wobulili wengane, futhi uzimisele ngesikhathi sokukhulelwa, futhi confluence we kwabesifazane nabesilisa ubulili amaseli.