Antibiotics: Tetracycline and Gram Negative Cell Walls

Overview

Recall questions on Tetracycline and Gram Negative Cell Walls.

What you need to know

Answer each one before you reveal it.

Questions from this subtopic

Each one with the model answer underneath.

1. 1

   Which type of antibiotic is tetracycline?

   Model answer

   Tetracycline is bacteriostatic and broad spectrum.

2. 2

   Describe the mode of action of tetracycline.

   Model answer

   It binds to the smaller subunit of the bacterial ribosome and prevents transfer RNA attaching, so amino acids cannot be added to the growing polypeptide and protein synthesis stops.

3. 3

   Why does blocking protein synthesis prevent bacterial growth?

   Model answer

   Without new enzymes and structural proteins the cell cannot build new cytoplasm or wall material, so it cannot grow or divide.

4. 4

   Why does tetracycline not block protein synthesis in the patient's own cells?

   Model answer

   Bacteria have 70S ribosomes while the ribosomes in the cytoplasm of human cells are the larger 80S type, and tetracycline binds only to the bacterial form.

5. 5

   How does the cell wall of a Gram negative bacterium differ from that of a Gram positive one?

   Model answer

   A Gram negative cell has only a thin layer of peptidoglycan, but outside it there is an additional outer membrane containing lipopolysaccharide, which the Gram positive cell, with its thick peptidoglycan layer, does not have.

6. 6

   How does the outer membrane of a Gram negative bacterium protect it from penicillin?

   Model answer

   The lipopolysaccharide membrane is impermeable to the antibiotic, so penicillin cannot reach the thin layer of peptidoglycan beneath it.

Other ways to work this

The same content, four other ways.

What is inside Levo

Six ways to work the same material.