The gene trpA in E.coli codes for the enzyme tryptophan synthase which is involved in biosynthesis of the essential amino acid tryptophan. Assume you have the wild type and mutant (that has non-functional trpA, called trpA) strains. How would you use the mutant E. coli to clone the correct version of the trpA gene? Give the limitations of this marker rescue method in cloning. Hint: the mutant type is able to survive only if tryptophan is added to the growth medium. (12 marks) In