Question

1) Describe the function of each antibiotic. Does the antibiotic inhibit cell wall synthesis, inhibit protein synthesis, or something else?

A) Penicillin

B)Tetracycline

C) Macrolide

D) Cephalosporin

E) Metronidazole

F) Vancomycin

G) Trimethoprim

H)Chloramphenicol

I)Rifampin

Answer 1

Ans 1a) Penicillin is beta lactum antibiotic which functions by inhibiting the cell wall synthesis. The bacteria is killed by the penicillin as the cross linking activity of bacteria is inhibited thereby formation of new cell wall is prevented. In the gram negative bacteria like Escherichia coli this antibiotic cannot enter due to presence of an endotoxin called lipopolysaccharide in their cell wall.

b) Tetracycline drug inhibit the protein synthesis.
It functions by inhibiting the process of translation as tetracycline binds to the smaller subunit of ribosome that is 30S. Also, tetracycline will not allow the aminoacyl tRNA to bind to the mRNA.

c) Macrolide functions by inhibiting the protein synthesis
Macrolide will interfere the protein synthesis as it will stop the activity of enzyme peptidyl transferase to form a peptide bond as new amino acid is not added thus the protein synthesis is inhibited.

d) Cephalosporin functions by inhibiting cell wall synthesis
It will function as the activity of enzyme transpeptidases are inhibited thus the cross linking that is showed by the peptide chain is interrupted thereby no stability is provided to cell wall hence , they inhibit the synthesis of cell wall.

e) Metronidazole is used for the treatment of various infections. It will function by inhibiting the bacterial growth. The activity of this drug is limited to only certain parasitic or bacterial infection.

f) Vancomycin function by inhibiting cell wall synthesis
It is an antibiotic made of glycopeptide thus the incorporation of NAG and NAM is prevented into the matrix of peptidoglycan thus cell wall synthesis is inhibited. It is a narrow range antibiotic as this drug cannot penetrate the gram negative cell wall.

g) Trimethoprim functions by inhibiting the DNA synthesis of bacteria.
This antibiotic will bind to the enzyme dihydrofolate reductase thus its ability to reduce dihydrofolic acid to tetrahydrofolic acid is inhibited. As synthesis of tetrahydrofolic acid is essential for producing pyrimidine which is interferred by the action of drug trimethoprim.

h) Chloramphenicol functions by inhibiting the protein synthesis
The antibiotic will prevent the peptide bond formation as it will bind to the ribosomal 50S subunit.

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