When the recombinant plasmid is grown in tetracycline medium then it will die. In this way we can distinguish transformant from non transformant. But if it has already died then how can they be further used in the production of products?
Answers
Answer:
Some genes called selectable markers help in selecting those host cells which contain the transformed vectors and eliminate the non-transformants.
Transformation is a process through which a piece of DNA is introduced in a host bacterium.
Generally, the genes encoding resistance to antibiotics such as tetracycline, ampicillin and kanamycin are useful selectable markers for E. coli.
Plasmid pBR322 has two resistance genes—ampicillin resistance (ampR) and tetracycline resistance (tetR)—which are considered useful for selectable markers.
Insertion of the DNA fragment into the plasmid using enzyme PstI or PvuI places the DNA insert within the gene ampR, which makes ampR non-functional.
Bacterial cells containing such a recombinant pBR322 will be unable to grow in the presence of ampicillin but will grow on tetracycline.
These recombinants can then be used for the production of useful products.
Explanation: