A strain of E.coli with the genotype arg^-bio^-gal^-Tet^R is able to grow on minimal medium (containing glucose as a carbon source)supplemented with: A)the amino acid arginine and the antibiotic tetracycline. B)the amino acid arginine and the vitamin biotin. C)the amino acid arginine and the sugar galactose. D)the vitamin biotin and the sugar galactose. E)the sugar galactose and the antibiotic tetracycline.

Question

Quizplus · Accepted Answer

The genotype of the E.coli strain suggests that it is auxotrophic for arginine (argS), biotin (bioS) and galactose (galS), and resistant to tetracycline (TetS). Therefore, the strain will require arginine and biotin to grow. Glucose is already provided in the medium. Galactose is not necessary since it is not the carbon source. Tetracycline resistance does not mean that the strain can grow in the presence of tetracycline alone, as it will still require other essential nutrients such as amino acids and vitamins. Therefore, the best choice is option B, which provides the two required nutrients, arginine and biotin.

A Strain of E