Agroup of nursing students are reviewing information about penicillins. the students demonstrate understanding of the information when they identify the action of penicillinase as causing bacterial resistance by which mechanism?
a. destruction of the beta-lactam ring of the penicillin
b. destruction of the penicillin cell wall
c. rupture of the penicillin membrane
d. enzymatic inactivation of the penicillin

A. destruction of the beta-lactam ring of the penicillin

Explanation:

Penicillins and other antibiotics in the beta-lactan family usually contain a characteristic four-membered ring of beta-lactam.

A penicillin is capable of killing bacteria by binding β-lactam to DD-transpeptidase (a bacterial enzyme that binds peptidoglycan chains to form rigid moving cell walls), inhibiting its activity and preventing the formation of a new cell wall.

Without a cell wall, bacterial cells become vulnerable to external water and molecular pressures, and thus die quickly.

Bacteria can generate resistance to penicillin by producing beta-lactamase, a bacterial enzyme that destroys the penicillin beta-lactan ring, rendering it ineffective.

An example of penicillin-resistant bacteria is Staphylococcus aureus, which produces high amounts of β-lactamase. This bacterium can cause skin, blood or lung infections.

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.