cau 11 :

- Sau khi bien nap ADn tai to hop vao tb VK , cong viec tiep theo la kiem tra su hien dien cua ADN la mong muon chon loc dung nhung tb mag ADN la va nhan len thanh dong , tao dk cho gen la bieu hien.

* XAc dinh  dong plashmid tai to hop

- Tb vk k nhan dc plashmid

- Tb VK nhan dc plashmid k mag gen la

- TB VK nhan dc dung plashmid tai to hop

HIen nay co nhieu pp de chon loc dong vk mang gen tai to hop nhu pp lai acid nucleic, fat hien va fan ung mien nhiem. Tuy nhien cac pp thuong dc su dung de ktra su hien dien cua ADN tai to hop la pp bo sung &( ampha ) , pp dung gen khang chat khang sinh .

a, DUNg gen khang chat khang sinh danh dau : 1 so vector plashmid thuong mag gen khang Ampicilin va gen khang Tretracilin . Khi gan gen la vao vector chuyen gen ng ta thuong chu tam gan vao vi tri diem gioi han nam ben trong cua 1 trong 2 gen nay va lam mat hoat tinh khang thuoc cua no . ( vd : mat hoat tinh gen TcR ) Khi cay VK da dc bien nap tren mt co thuoc khang sinh la ampicilin  va tretracilin thi nhung vk bj uc che boi tretracilin chung to bi mat hoat tinh khang tretracilin do doan gen la dc chon loc ra va nhan len thanh dong

b, PP bo tro nhan : he thong X-gal cung co the dc dung de chon loc cac the ADN tai to hop. Neu doan ADN la dc gan xen vao giua gen loc Z thi enxyme be ta-galactosidase k dc san sinh ra khi co mat lactose trong mt nuoi cay . Nhu vay cac tb VK chua plashmid mag gen tai to hop se tao khuan loc mau trang tren moi truong co bo sung X-gal . COn co cac tb mang plashmid k tai to hop van giu nguyen gen loc Z hoat dong nen tao cac khuan lac mau xanh . PP nay cung co the dc su dung vs he thong bo tro k xay ra trong tb chu nen cac khuan lac se co mau trang .