In Gram staining, crystal violet (a violet dye) is used to specifically stain Gram-positive bacteria. After performing Gram staining on a bacterial sample taken from an infected animal tissue, you observe the results with a microscope. You find two major types of bacteria in the sample, as shown in the schematic drawing below. According to these results, indicate whether each of the following statements is correct (C) or incorrect (I). Your answer would be a three-letter string composed of letters C and I only, e.g. CCC.

( ) The Gram-positive bacteria in this sample are bacilli.
( ) Crystal violet stains lipopolysaccharide (LPS).
( ) The bacteria stained violet in this sample have a thicker layer of peptidoglycan compared to the other bacteria.

Question

In Gram staining, crystal violet (a violet dye) is used to specifically stain Gram-positive bacteria. After performing Gram staining on a bacterial sample taken from an infected animal tissue, you observe the results with a microscope. You find two major types of bacteria in the sample, as shown in the schematic drawing below. According to these results, indicate whether each of the following statements is correct (C) or incorrect (I). Your answer would be a three-letter string composed of letters C and I only, e.g. CCC.
  
( )	The Gram-positive bacteria in this sample are bacilli.
( )	Crystal violet stains lipopolysaccharide (LPS).
( )	The bacteria stained violet in this sample have a thicker layer of peptidoglycan compared to the other bacteria.

Quizplus · Accepted Answer

Gram-positive bacteria (the cocci in this example) have a thicker layer of peptidoglycan cell wall. LPS is found on the outside of Gram-negative bacteria.

In Gram Staining, Crystal Violet (A Violet Dye) Is Used