Question

Below are 6 steps involved in the evolution of Ab resistance, listed in a scrambled order. Organize the steps in the order in which they actually occur :

1. An advantageous mutation occurs that does not influence Ab-resistance, but increases growth rate.

2 Antibiotics are introduced into the environment.

3 A deleterious mutation occurs in a single cell that confers antibiotic resistance but compromises growth rate.

4 The individual cell with the Ab-resistant allele survives and reproduces slowly.

5 The antibiotic is more-or-less obsolete (useless, ineffective).

6 Selection favors compensatory mutations in the Ab-resistant population to favor the evolution of higher growth rates.

Answer 1

Development of antibiotic resistance is a gradual process in which an organism undergoes desensitization against a single or group of antibiotics thereby showing failure of effects of the same. Studies have shown that when an organism develops resistance, these changes are slowly Incorporated into its genome as a permanent alteration thus leading to genetic establishment of these changes. Thus, this leads to generation of a new set of organisms which have been evolved as compared to other set of organisms with respect to that antibiotic or set of antibiotics. Thus, the correct set of events can be found as below:

2, 1, 3, 4, 6 and 5.