18 Questions
What is the role of the bacterial cell membrane in maintaining a constant inner bacterial environment?
Controlling transport mechanisms
Which of the following best describes the Gram-negative cell wall?
Contains Lipopolysaccharide (LPS) which is extremely toxic to the human body
Which statement accurately describes the medical importance of Gram-negative bacteria's lipopolysaccharide (LPS)?
All of the above
Which process requires sterilization by boiling at 100°C for 20-30 minutes to free instruments and products from spores for medical use?
Spore elimination
What is a distinguishing feature of Gram-negative cell walls compared to Gram-positive cell walls?
Thin layer of peptidoglycan (2 sheets forming 5-10% of the cell wall material) located inside the outer layer of LPS
What is true about Gram-negative cell walls?
Outer membrane contains porins for selective permeability
What is the outer layer of lipopolysaccharides in gram-negative bacteria called?
Somatic O antigen
When is the endotoxin released in gram-negative bacteria?
When bacterial cells are lysed
Which component of lipopolysaccharides is responsible for the toxicity in gram-negative bacteria?
Lipid A
What symptoms are caused by the fever, hypotension, and shock in the human body due to lipopolysaccharides?
Toxic shock syndrome
Where is the Somatic O antigen located in gram-negative bacteria?
Outer layer of lipopolysaccharides
What is the function of Lipid A in lipopolysaccharides of gram-negative bacteria?
Responsible for toxicity
What is the main function of the bacterial cytoplasmic membrane?
Controlling transport mechanisms
Which statement best describes the Gram-negative cell wall?
Contains Lipopolysaccharide (LPS) which is extremely toxic to the human body
What is the role of Lipopolysaccharide (LPS) in Gram-negative bacteria?
All of the above
Which aspect determines the reaction of bacterial cells to the Gram stain?
Bacterial cytoplasmic membrane function
What is the medical importance of bacterial spores?
They are highly resistant to environmental stressors
Why is Lipopolysaccharide (LPS) considered a critical component in Gram-negative bacteria?
It triggers immune responses and can cause severe symptoms in humans
Study Notes
Bacterial Cell Membrane Function
- Maintains a constant inner bacterial environment by controlling transport mechanisms
- Does not determine cell reaction to Gram stain, play a role in cell division, or maintain shape and Gram character of bacteria
Gram Negative Cell Wall
- Contains Lipopolysaccharide (LPS) which is extremely toxic to the human body and is called the endotoxin
- LPS is released only when the bacterial cells are lysed, and is responsible for the fever, hypotension and shock caused by gram negative organisms
- Has a thin layer of peptidoglycan (2 sheets) which forms only 5-10% of the cell wall material, located inside the outer layer of LPS
Gram Positive Cell Wall
- Contains a thick peptidoglycan layer (40 sheets) responsible for bacterial rigidity and shape
- Has teichoic and lipoteichoic acid, which are major surface components, immunogenic, and responsible for Toxic shock symptoms and adherence to host cells
Periplasmic Space
- Is the space between the outer and inner layer of cytoplasmic membrane
- Filled with a gel solution of proteins
- Is the site of β-lactamase enzymes in some bacteria that degrade penicillins and other β-lactam drugs
Functions of Cell Wall
- Maintains the shape of bacteria
- Osmotically insensitive, protecting the cytoplasmic membrane against bursting in hypotonic solutions
Test your knowledge on bacterial cell membrane function with these multiple-choice questions. Identify true statements regarding the role of the cell membrane in maintaining shape, Gram stain reaction, and inner bacterial environment.
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