1. An interrupted mating experiment is performed between an Ampicillin-sensitive
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1. An interrupted mating experiment is performed between an Ampicillin-sensitive, prototrophic HFR strain and an Ampicillin Resistant his- leu- trp- met- arg- auxotrophic strain. The following results are obtained: Numbers of colonies of each Genotype over time Minutes before mating interrupted 10 20304050 60 7080 colony genotype his 12280 275 292 301 80297 289295 301303299 35 286 79301 287 304 304 298 297 12199 300 301 298 287289 301 0 leu 0 0 0 met ar Draw a time-of-transfer map showing the F integration site relative to the his, leu, trp, met and arg genes. 10 Arg 20 40 70 F+ Leu His Trp MetExplanation / Answer
It says that mating is inturrepted meaning basically the transfer of F+ plasmid is inturrepted due to which the whole plasmid could not be transferred from one F+ microorganism to another F- organism.
Now, simply look what happen if mating is stopped at 10 minute, only colonies with gene for arginine are recovered meaning arginine is the first one to be transferred so it came first.
next at 20 minutes, obviously arginine is transfered already by this time, so next one that was transfered could be leucine or met. It can not be exactly known since colonies for both are almost equally present so they must be very close in F+ plasmid as well.
At 30 minutes, no extra gene is transferred meaning there is a gap where there is no gene whatsoever.
At 40 minute, 12 colonies of histidine appears meaning its next and same goes for tryptophan for 70 minutes.
Thats how you get the map below.
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