Question

a everytime an antibiotic is used in humans or animals,there is a risk that antibiotics resistance will be become more common in bacteria. use what you know about natural selection and evolution to explain how bacteria become resistant to antibody. b.   what effect would transduction, transformation and conjugation have on the amount of antibiotic resistance in bateria? explain.

Answer 1

On exposure to antibiotics, most of the bacteria that are susceptible in a population dies out. However, resistant ones survive and multiply. Subsequently, the entire population consists of resistant ones.Their resistance is attributed to certain mutations in their genome.Therefore,antibiotics act as selective agents for the evolution of antibiotic resistant strains of bacteria.

Transduction, transformation and conjugation are the three mechanisms for horizontal gene transfer among bacteria. Horizontal gene transfer is the transfer of DNA between uni/mulicellular organisms other than from parent to offspring. Mechanisms of horizontal gene transfer increases the incidence of antibiotic resistance.

Uptake of naked DNA molecule from the environment is called transformation. Any gene can be taken in this manner including antibiotic resistance genes.

Direct transfer of genetic material between bacterial cells through pilus is called conjugation. Mostly in conjugation, the recipient receives a copy of a plasmid from the donor. Most antibiotic resistant genes are plasmid encoded.

In transductiom, bacteriophages act as vectors and transfer genetic material from donor bacteria to recepient. Genes obtained through horizontal gene transfer may be eliminated by recipient. However, if they provide any survival advantage as in case of antibiotic resistant genes, it may retained by the bacteria.