1. What information/structures were you able to glean from the Gram stain that you could not get from the methylene blue stain?

2. What information/structures were you able to glean from the methylene blue stain that you could not get from the Gram stain?

3. Is Saccharomyces cerevisiae Gram-positive or Gram-negative?

4. Research and describe the composition of yeast cell walls. How does the composition compare to the cell walls of Gram-positive or Gram-negative bacteria?

Answer 1: Gram staining can stain the outer structure of cell such as cell wall and cell membrane. This stain used to identify the gram positive and gram negative cell in a cluster of bacterial colony. These structure can not be stained by using methylene blue.

Answer 2: Methylene blue stain used to stain the internal structures of the cell including DNA in nucleus and RNA fractions in cytoplasm. These structures can not be stained and identified using gram staining.

Answer 3: A research paper (J. gen. Microbiol. (1963), 30, 223-235) stated that Saccharomyces cerevisiae is a gram positive bacteria.

Answer 4: A research paper (The Chemical Composition and Structure of the Yeast Cell Wall) provided the actual and true composition of yeast cell wall. According to this paper, yeast cell wall is composed of protein (13%), lipids (8.5%), and Polymaccharides (78%). While on the other hand cell wall of gram positive bacteria is composed of peptidogylcane (50-60%), lipids (1-4%), teichoic acid and lipoteichoic acid. Further, cell wall of gram negative bacteria composed of lipopolysacharides, lipoproteins, peptidoglycane and lipids (11-12%).