Microbiology: Gram-Positive vs. Gram-Negative and Gram Staining

Flashcards based on lecture notes detailing the structural differences between Gram-positive and Gram-negative bacteria, the role of porins and endotoxins, and the sequential steps of the Gram stain.

What is the relationship between Lipid A, Endotoxin, and Danger?

Lipid A is an Endotoxin and is identified as Danger.

What are porins and where are they located?

They are protein channels located in the outer membrane of Gram negative bacteria.

What is the function of porins?

Allow molecules to enter the cell and transport them, while limiting the size of molecules entering (like security doors).

How does the thickness of Peptidoglycan differ between Gram Positive and Gram Negative bacteria?

Gram Positive has a thick layer of Peptidoglycan, while Gram Negative has a thin layer.

Which type of bacteria contains Teichoic acids?

Gram Positive

Which type of bacteria possesses an outer membrane, LPS, O antigen, and Lipid A (Endotoxin)?

Gram Negative

Are Periplasm and Porins found in Gram Positive or Gram Negative bacteria?

Gram Negative

What are the four steps of the Gram stain in order?

1. Crystal violet, 2. Iodine, 3. Alcohol, 4. Safranin

What forms inside all bacteria during steps 1 and 2 of the Gram stain process?

$CV-I2$ crystals (formed by Crystal violet + iodine)