Question 2- Gram Staining

Question 1

Explain the mechanism of gram staining (hint: steps in Gram Staining, Differences between gram positive and negative cell wall) - Draw a diagram to explain

Answer 1

The basic principle of gram staining involves the ability of the bacterial cell wall to retain the crystal violet dye during solvent treatment. Gram-positive microorganisms have higher peptidoglycan content, whereas gram-negative organisms have higher lipid content.

Gram-negative bacteria are surrounded by a thin peptidoglycan cell wall, which itself is surrounded by an outer membrane containing lipopolysaccharide. Gram-positive bacteria lack an outer membrane but are surrounded by layers of peptidoglycan many times thicker than is found in the Gram-negatives.

The cell wall of gram-positive bacteria is consisting of thick layers of peptidoglycan. Whereas the cell wall of gram-negative bacteria is consisting of thin layers of peptidoglycan.

Question 2

Why is it important to distinguish between Gram Positive and Gram Negative Bacteria?

Answer 2

Gram-negative bacteria are more resistant to antibodies because their cell wall is impenetrable.
Gram-positive bacteria cause tremendous problems and are the focus of many eradication efforts, but meanwhile, Gram-negative bacteria have been developing dangerous resistance and are therefore classified by the CDC as a more serious threat.

Question 3

According to the mechanism you discussed, which bacteria do you think is more permeable to a series of antibiotics and why?

Answer 3

The cell-wall of gram-positive bacteria, which is simply structured, is therefore more permeable to a series of antibiotics than is the gram-negative cell-wall which is built like other biological membranes.

A Gram positive organism lacks an outer (LPS) membrane but has a thick layer of peptidoglycan and no LPS outer membrane. This facilitates access of cell-wall active antibiotics