An Hfr strain is used to map three genes in an interrupted mating...

Question

An Hfr strain is used to map three genes in an interrupted mating experiment. The cross is Hfr/a⁺b⁺c⁺ rif x F⁻/a⁻b⁻c⁻ rif^T (No map order is implied in the listing of the alleles; rif^T is resistance to the antibiotic rifampicin.) The a⁺ gene is required for the biosynthesis of nutrient A, the b⁺ gene for nutrient B, and c⁺ for nutrient C. The minus alleles are auxotrophs for these nutrients. The cross is initiated at time = 0 and at various times, the mating mixture is plated on three types of medium. Each plate contains minimal medium (MM) plus rifampicin plus specific supplements that are indicated in the following table. (The results for each time interval are shown as the number of colonies growing on each plate.)

Time of Interruption _
5 min 10 min 15 min 20 min
Nutrients A and B 0 0 4 21 
Nutrients B and C 0 5 23 40 
Nutrients A and C 4 25 60 82

Can the location of the rif gene be determined in this experiment? If not, design an experiment to determine the location of rif relative to the F factor and to gene b.

Accepted Answer

Hello everyone and welcome to today's video. So the f minus train called the recipient appears to have the ton our gene after 12 minutes. The Az Arjun after 18 minutes and the his plus jean after 14 minutes from an HFR strain. In an interrupted meeting experiment. However the recipient almost never has the lack plus jean. So where in the genome is this origin of transfer? So the main premise here is that the closer a gin is to the origin of transfer, the faster it is going to be obtained by this recipient cell. So the faster gene to be obtained is its own origin. Then we have the his place gene and then we have the AZ origin. This is the order based on the time that it took for these genes to be obtained by the recipient cell. However, we are told that the recipient cell almost never has this black plus jean. And this is because it is located farthest at the end of this order. And by that time congregation reaches this step the tube or the palace usually breaks and it cannot be transferred. Now remember that these bacterial chromosomes are going to be circular meaning that these two ends are going to be together. This is the first one. This is the final end. So it is going to be somewhere between these two. The origin of transfer Because of this. The correct answer choice is going to be answer choice between ton or which is the start aging and lack plus which is the final gene or the gene that just never gets transferred. I really hope this video helped you, and I hope to see you on the next one.

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