Mene ne biyu-matasan crossover

Dokokin gado Mendel for monohybrid giciye kiyaye su a cikin hali na karin hadaddun biyu-matasan. A irin wannan hulda iyaye siffofin bambanta da nau'i biyu daga contrasting halaye.

Yi la'akari da misalin Mendel dihybrid giciye kuma tabbatarwa dokokin. Haye biyu irin Peas: tare da fararen furanni da wata al'ada baki, da shunayya, da furanni da kuma elongated baki. All farko-tsara mutane da al'ada fararen furanni tare da wani whisk. Daga wannan ne zamu gane cewa da farin launi (denoted da C) da kuma al'ada tsawon (rubuta E) - shi ne rinjaye siffofi da wani m launi (s) da kuma wani elongate whisk (e) - recessive. Lokacin da kai-pollination na ƙarni na farko na shuke-shuke da aka raba. Domin kare kanka da tsabta samar da mararraba makirci.

Da farko giciye: P1 x CCEE CCEE

G 2Ss da 2Ee

F1 CCEE

Na biyu ma'abota (selfing F1 hybrids) P2 x CCEE CCEE. Dihybrid giciye ke nunawa 16-daban na zygotes. Kowane gamete zai dauke daya wakilin daga gene da nau'i-nau'i tare da P-da E-E nau'i-nau'i. Lokacin da wannan gene C da daidai yiwuwa za a iya hade tare E ko e bi da bi, kuma zai iya hada da E, ko E A sakamakon matasan CCEE siffofin tare da daidaita mita na gamete iri 4: .. AZ, Ge, Ce, AZ. Obedin tare, suka samar da irin wannan kwayoyin: 9 tare da al'ada fari corolla, tare da 3 fari elongate whisk 3 tare da wata al'ada baki magenta da magenta 1 da wani elongated baki.

A karo na biyu ƙarni ta tsallaka hybrids baya, zahiri kama iyayentaka siffofin, siffofi suna kafa tare da wani sabon hade da haruffa (combinative ko kwayoyin canzawa). Wannan sabon abu taka muhimmiyar rawa a juyin halittar da ake samu sabon haduwa da Na'urar halaye. Har ila yau, rayayye amfani da kiwo, inda crossbreeding na shuke-shuke da dabbobi na inganta iri da kuma breeds ya sa ya yiwu don gabatar da sabon nau'in.

Yawan phenotypes a F2 ne kasa da adadin genotypes. Wannan shi ne saboda gaskiyar cewa ƙungiyar na daban-daban gametes iya bayar da wannan morphological halaye. Saboda haka, da muka samu cikin tsagawa da phenotype - 9: 3: 3: 1.

Wannan biyu-matasan crossover ne yiwu idan da rinjaye kwayoyin halittu suna located in nonhomologous chromosomes. Cytological tushen irin wannan ci da kuma sake - meiosis da hadi. Mendel ya lura cewa da irin wannan hulda da genes kowane biyu daga halayen gaji da kansa juna, da yardar kaina ana hade a duk yiwu haduwa (m gado).

Duk da alamu na gado cewa Mendel kafa for guda da kuma biyu-matasan ma'abota, halayyar mafi hadaddun haduwa. Saboda haka, poligibridnoe mararraba faruwa a lokacin da kwayoyin da ake dauka domin wannan rarrabe uku ko fiye da contrasting fasali. A zuciya na wannan Fusion na gametes da redistribution kayyade bayanai ne da dokokin narkewa da masu zaman kansu na gādo.

Daga cikin gabatar ba, mun gama da cewa biyu-matasan crossover - An, a gaskiya, biyu da kansa-kai talakawa mararraba, inda daya madadin alamar da aka ɗauke shi zuwa lissafi (monohybrid). Wannan gaskiya ne ga shuke-shuke da dabbobi.