Question

Jason adds the antibiotic penicillin to a bacterial culture. The bacteria develop genetic modifications in their genome, which gives them resistance to the antibiotic penicillin. What caused this genetic modification? A. mutations to the DNA sequence B. normal gene regulation C. operon gene induction D. RNA interference

Answer 1

The correct answer would be A. mutations to the DNA sequence.

Penicillin acts on bacterial cell by developing pores in their cell membrane.

It does so by binding to the enzyme transpeptidase which is responsible for catalyzing the cross-linking of peptidoglycans in the cell wall (helps in synthesis of cell wall).

Thus, inhibition of this enzyme would stop the synthesis of cell wall. Loosening of the cell wall would lead to formation of pores which ultimately leads to the death of the bacteria.

Now, mutation in the transpeptidase encoding DNA can result in change of shape of penicillin binding site of this enzyme. Hence, penicillin would not be able to bind the mutated enzyme and thus it would not be inhibited.

Ultimately, the bacteria would become resistant to this antibiotic.