what are counter selectable marker in hfr mating
Answers
In contrast to selection markers, counter-selection markers serve to eliminate unwanted elements. These markers are often toxic or otherwise inhibitory to replication under certain conditions. Selective conditions often involve exposure to a specific substrates or shift in growth conditions.
Answer:
Recall that spontaneous breakage creates a natural gradient of transfer, which makes it less and less likely for a recipient to receive later and later markers. Because we have selected for the earliest marker in this cross, the frequency of recombinants is a function of the order of entry for each marker. Therefore, we can immediately determine the order of the genetic markers simply by looking at the percentage of recombinants for any marker among the leu+ recombinants. Because the inheritance of thr+ is the highest, this must be the first marker to enter after leu. The complete order is leu, thr, ile, mal, trp.
Explanation:
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