Question

Which of the following statements regarding antibiotics is not correct?
i) Antibiotics are the attenuated microorganisms which in small concentrations, can kill or retard the growth of other harmful microorganisms.
ii) Penicillin was the first antibiotic to be discovered by Alexander Fleming (1928) while working on the bacterium Staphylococcus aureus.
iii) The full potential of penicillin as an effective antibiotic was established by Ernest Chain and Howard Florey.
iv) Fleming, Chain, and Florey were awarded the Nobel Prize.
A. (i) only
B. (iii) only
C. (ii) and (iv)
D. (i), (iii) and (iv)

Answer 1

Hint: Penicillin was obtained from the fungus Penicillium notatum but the highest source of penicillin is obtained from Penicillium chrysogenum. It was first used clinically in the year $1941$, consisting of a β- lactam ring fused with a thiazolidine ring, and to the β-lactam ring, sidechains are attached through an amide linkage. The naturally obtained penicillin (Penicillin-G) has a benzyl sidechain attached to the amide linkage.

Complete answer:
Antibiotics are the substances that are produced by the microorganism, which selectively suppress the growth of or kill other microorganisms at low concentrations, hence attenuated microorganism as a whole is not used as an antibiotic, rather the substance that is obtained from the microorganism gives the therapeutic value, hence the option (i) is incorrect,

So option A is the correct option.

Additional Information:
The discovery of penicillin was accidental in the year $1928$ when Alexander Flemming observed the growth of a mold in a culture of Staphylococcus aureus in the lab, hence the statement in option (ii) is correct.
Flemming from London University, Chain and Florey both from Oxford University were awarded the Nobel prize for the discovery of Penicillin in the year $1945$, hence the statement in option (iv) is correct.
As the option (ii) and (iv) are correct therefore according to the question option C becomes incorrect.
The full potential of penicillin as an antibiotic was discovered by Ernest Chain and Howard Florey, hence the statement (iii) is correct and thus the option B is incorrect.
As the statement is (ii) and (iv) are correct so the option D becomes incorrect.

Note:
Penicillin acts by stopping the cell wall synthesis by binding to the transpeptidase enzyme which is an essential component for the crosslinking of the units of the cell wall. Penicillin is an acid-labile compound and degrades readily in the stomach and at the same time is inactivated by the enzyme penicillinase for this reason penicillin-resistant bacteria exist, penicillin has a narrow spectrum of activity.