Gram-positive bacteria

Definition

Gram-positive bacteria are characterized by a thick peptidoglycan layer in their cell walls, which retains the crystal violet stain used in Gram staining. These bacteria lack an outer membrane found in Gram-negative bacteria.

5 Must Know Facts For Your Next Test

1. Gram-positive bacteria appear purple under a microscope after Gram staining due to their thick peptidoglycan layer.
2. Common examples include Staphylococcus and Streptococcus species.
3. They are generally more susceptible to antibiotics like penicillin that target cell wall synthesis.
4. Teichoic acids and lipoteichoic acids are present in their cell walls, contributing to the rigidity and regulation of cell growth.
5. They can form endospores, making them highly resistant to environmental stressors.

Review Questions

• What is the primary structural difference between gram-positive and gram-negative bacteria?
• Name two common genera of gram-positive bacteria.
• Why are gram-positive bacteria generally more susceptible to antibiotics targeting cell wall synthesis?

Related terms

Gram-Negative Bacteria: Bacteria with a thin peptidoglycan layer and an outer membrane that do not retain the crystal violet stain.

Peptidoglycan: A polymer consisting of sugars and amino acids that forms a mesh-like layer outside the plasma membrane of most bacteria.

Endospore: A tough, dormant structure formed by some bacteria allowing them to survive extreme conditions.