To map genes of a bacterial strain, conjugation must be interrupted at given times. Suppose you have Hfr cells of genotype a⁺b⁺c⁺d⁺e⁺str^R and F^- cells of genotype a^-b^-c^-d^-e^-str^S and you combine these two cultures in liquid medium in four blenders at time 0. After intervals of 3, 6, 9, and 12 minutes, you turn on successive blenders. This graph shows the results of plating the cultures of each blender. What is the correct order of the genes on this chromosome? A)a b c d e B)a c e b d C)b e c a (d is unknown) D)d a c e b E)b e c a d

Question

Quizplus · Accepted Answer

The order of the genes can be determined by analyzing the pattern of the transfer of markers at different time points. The first transferred gene should be the one closest to the origin of transfer. From the graph, it is clear that gene a is transferred first, followed by c, then e, then b, and finally d (which is not transferred in the experiment). Therefore, the correct order is a-c-e-b-d, which corresponds to choice B.

To Map Genes of a Bacterial Strain, Conjugation Must Be