10 Questions
What is the characteristic of the cell wall of gram-positive bacteria that allows them to retain the crystal violet stain?
Thick layer of peptidoglycan
What is the main component of the cell wall of acid-fast bacteria that makes them resistant to decolorization?
Mycolic acid
Which type of bacteria lacks a cell wall entirely?
Mycoplasmas
What is the characteristic of the cell wall of archaea?
Lack of peptidoglycan
What is the function of sterols in the cell membrane of mycoplasmas?
To provide added strength to the cell membrane
Which type of bacteria has a cell wall that is most similar to the cell walls of archaea?
Gram-negative bacteria
What is the primary function of lipopolysaccharides in the outer membrane of gram-negative bacteria?
To enhance the bacterium's ability to evade the host's immune system
Which type of bacteria is most likely to be affected by the decolorization step in acid-fast staining?
Acid-fast bacteria
What is the primary component of the cell wall of gram-positive bacteria that allows it to retain the crystal violet stain?
Peptidoglycan
Which type of bacteria is likely to have a cell membrane that is more resistant to osmotic stress?
Mycoplasmas
Study Notes
Cell Walls of Different Bacteria and Microorganisms
- Gram-positive bacteria have a thick layer of peptidoglycan in their cell wall, which retains the crystal violet stain used in the Gram stain procedure.
Characteristics of Cell Walls
- Gram-negative bacteria have a thinner peptidoglycan layer and an outer membrane containing lipopolysaccharides (LPS), which does not retain the crystal violet stain but takes up the counterstain (safranin).
- Acid-fast bacteria have a waxy lipid (mycolic acid) in their cell wall, which makes them resistant to the decolorization step in acid-fast staining.
Unique Cell Walls
- Archaea lack peptidoglycan in their cell walls and instead have pseudopeptidoglycan or other complex polysaccharides.
- Mycoplasmas lack a cell wall entirely and have a cell membrane containing sterols for added strength.
Test your knowledge on the differences in cell walls of various microorganisms, including gram-positive and gram-negative bacteria, acid-fast bacteria, archaea, and mycoplasmas. Understand the characteristics that distinguish one from another. Learn about the composition and function of their cell walls.
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