Question

III. You isolate a new species of bacteria that only grows in the Antarctic. A wild type strain of this bacteria can synthesize its own alanine (alat) and its own tryptophan trp' ), both of which are essential amino acids. A mutant strain of the same bacterium cannot synthesize either of those two amino acids (ala trp'). You are interested in the degree of linkage between the ala and the trp genes in this new bacterial species. Fortunately, this species is transformation competent. To determine the degree of linkage, you incubate the mutant cells (ala' trp') with DNA that you purified from the wild type strain (alat trp). The average length of the transforming DNA is 100,000 base pairs. After 20 minutes of incubation, you spread the bacterial cells on selective media and put them in an incubator overnight. The next day you count the number of colonies that grew on each of those media and identify the following three "progeny" classes: "Progeny" class Number of colonies 5,000 alat trpt ala trp alat trp 13.000 12.000 30,000 A. A medium that contained only alanine (and a carbon/energy source like glucose) would select for what specific genotype(s) at the ala and trploci? B. What specific selective medium media would you have used to detect the o De MS 19