A Transformation Experiment Is Performed with a Donor Strain That

Multiple Choice

A transformation experiment is performed with a donor strain that is resistant to four drugs, A, B, C, and D, determined by genes A, B, C, and D. The recipient strain is sensitive to all four drugs. The treated recipient-cell population is divided up and plated on media containing various combinations of the drugs. A cell that is resistant to the added drug(s) will form a colony. The table below shows the results. $$\begin{array} { l l l l } \text { Drug(s) Added } & \text { Number of Colonies } & \text { Drug(s) Added } & \text { Number of Colonies } \\\hline \text { None } & 10,000 & \mathrm { BC } & 51 \\\text { A } & 1,156 & \mathrm { BD } & 49 \\\text { B } & 1,148 & \mathrm { CD } & 786 \\\text { C } & 1,161 & \mathrm { ABC } & 30 \\\text { D } & 1,139 & \mathrm { ABD } & 42 \\\text { AB } & 46 & \mathrm { ACD } & 630 \\\text { AC } & 640 & \mathrm { BCD } & 36 \\\text { AD } & 942 & \text { ABCD } & 30\end{array}$$ One of the genes is quite distant from the other three that are tightly linked. What is the probable order of the three tightly linked genes?

A) DAC
B) ACB
C) BDC
D) DCA
E) ADC