Question

Antibiotics work by five major mechanisms. These are listed below. Several of these are obviously tied to our recent discussions of the genetic code. For each of the five mechanisms below, find an antibiotic that fits that category, and describe the disease it treats, and how it works:

1. Inhibition of Cell Wall Synthesis (most common mechanism)

2. Inhibition of Protein Synthesis (Translation) (second largest class)

3. Alteration of Cell Membranes

4. Inhibition of Nucleic Acid Synthesis

5. Antimetabolite Activity

Answer 1

1. Pencillin - Inhibits the enzyme catalyzing the transpeptidation reaction because of their structural similarity ( presence of beta lactam ring), which would block the synthesis of a complete fully cross-linked pepetidoglycan and leads to osmotic lysis.

Pneumonia, blood poisining, stept throat, scarlet fever, diptheria, syphilis, gonorrhea, meningitis, tonsillitis, rheumatic fever were treated with pencillin.

2. Tetracyclines- they have a common four ring structure to which a variety of side chains are attached. they will inhibit the A site of ribosomes.

tetracyclines are used to treat acne and other skin infections, respiratory tract infection ( pneumonia) and genital and urinary infections.

3. Polymixine B - Disrupts the structure and permeability of plasma membrane.

it treats nfections of the urinary tract, eye, ear, skin, bloodstream, and layers covering the brain (meninges) caused by sensitive gram-negative bacteria.

4. Ciprofloxacin - It inhibits the bacterial DNA gyrase enzyme, hence block replication.

It is used to treat infections of bones and joints, endocarditis, gastroenteritis, malignant otitis externa,respiratory tract infections, cellulitis, urinary tract infections, prostatitis, anthrax, and chancroid.

5. Sulfonamides - inhibits folic acid synthesis by competition with p-aminobenzoic acid.

they are used to treat Burns, Vaginitis, uperficial ocular infections.