Suppose that you could obtain radioactively labeled...

Name: Problem 33, Chapter 14: Genetics: From Genes to Genomes
Uploaded: 2021-11-19T14:42:04-08:00
Duration: 4 min 19 s
Channel: Rabeya Zahid
Description: Suppose that you could obtain radioactively labeled penicillin. How could you use this compound to distinguish whether a penicillin-resistant bacterium harbors a gene encoding penicillinase or whether the bacterium has acquired a mutation in penA , penB, or mtr?

Suppose that you could obtain radioactively labeled penicillin. How could you use this compound to distinguish whether a penicillin-resistant bacterium harbors a gene encoding penicillinase or whether the bacterium has acquired a mutation in penA , penB, or mtr?

Key Concepts

Mutation-Based Antibiotic Resistance

This concept covers resistance arising from genetic alterations in the target molecules of antibiotics, such as mutations in penicillin-binding proteins (encoded by genes like penA) or changes in membrane permeability or efflux systems (affected by genes like penB or mtr). These mutations prevent penicillin from effectively binding to its targets, and radioactively labeled penicillin can help determine if the drug remains intact but ineffective due to these mutations.

Biochemical Assay Techniques

This involves experimental methods that use labeled compounds to track biochemical interactions. In this scenario, the assay could involve comparing the radioactivity associated with intact penicillin versus that found in degraded products or in different cellular fractions. This differential analysis allows one to distinguish between resistance due to enzymatic breakdown and resistance due to mutations in target or transport systems.

Radioactive Labeling

This concept involves attaching a radioactive isotope to a molecule to trace its movement and interactions within a biological system. In the context of the experiment, radioactively labeled penicillin allows researchers to follow the fate of the antibiotic, determining whether it is being bound intact to bacterial targets or broken down by enzymes.

Enzymatic Antibiotic Resistance

This refers to the mechanism by which bacteria produce enzymes, such as penicillinase, to inactivate antibiotics. Penicillinase hydrolyzes the beta-lactam ring of penicillin, rendering the drug ineffective. By monitoring changes in radioactivity corresponding to degradation products, one can infer whether resistance is due to the action of such enzymes.

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