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Modern Genetic Analysis Chapter 9. The Genetics of Bacteria and Phages
Solved Problem

2. | In E. coli, four Hfr strains donate the following genetic markers shown in the order donated: All of these Hfr strains are derived from the same F+ strain. What is the order of these markers on the circular chromosome of the original F+? See answer

Solution

Recall the two-step approach: (1) determine the underlying principle and (2) draw a diagram. Here the relevant principle is that each Hfr strain donates genetic markers from a fixed point on the circular chromosome and that the earliest markers are donated with the highest frequency. Because not all markers are donated by each Hfr, only the early markers must be donated for each Hfr. Each strain allows us to draw the following circles:

From this information, we can consolidate each circle into one circular linkage map of the order Q, W, D, M, T, P, X, A, C, N, B, Q.

See question

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