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Questions and Answers
What is the primary concern of taxonomy?
What is the primary concern of taxonomy?
Which of the following is NOT a level of classification in the taxonomic hierarchy?
Which of the following is NOT a level of classification in the taxonomic hierarchy?
In the binomial system of nomenclature, how is the genus name characterized?
In the binomial system of nomenclature, how is the genus name characterized?
What defines a species in sexually reproducing organisms?
What defines a species in sexually reproducing organisms?
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Which of the following correctly describes a 'strain' in microbial taxonomy?
Which of the following correctly describes a 'strain' in microbial taxonomy?
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What is the primary focus of Bergey’s Manual of Determinative Bacteriology?
What is the primary focus of Bergey’s Manual of Determinative Bacteriology?
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Which resource primarily focuses on naming fungi?
Which resource primarily focuses on naming fungi?
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What characteristic defines bacterial cells compared to other organisms?
What characteristic defines bacterial cells compared to other organisms?
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Which database provides species names of known prokaryotes based on published articles?
Which database provides species names of known prokaryotes based on published articles?
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What type of information does Bergey’s Manual of Systematic Bacteriology provide?
What type of information does Bergey’s Manual of Systematic Bacteriology provide?
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What characteristic distinguishes prokaryotic cells like bacteria from eukaryotic cells?
What characteristic distinguishes prokaryotic cells like bacteria from eukaryotic cells?
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Which statement about fungi is most accurate?
Which statement about fungi is most accurate?
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Which type of organism does NOT belong to the class of parasites that can cause disease in humans?
Which type of organism does NOT belong to the class of parasites that can cause disease in humans?
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How do helminths differ from protozoa in terms of reproduction in humans?
How do helminths differ from protozoa in terms of reproduction in humans?
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What type of infection is commonly caused by fungi in the lungs?
What type of infection is commonly caused by fungi in the lungs?
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Which of the following statements about ectoparasites is true?
Which of the following statements about ectoparasites is true?
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Which of the following describes plasmids in bacteria?
Which of the following describes plasmids in bacteria?
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What is a primary challenge in treating protozoan infections?
What is a primary challenge in treating protozoan infections?
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What characterizes a virus in its extracellular state?
What characterizes a virus in its extracellular state?
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Which statement about the origin of viruses is correct?
Which statement about the origin of viruses is correct?
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What are the primary factors used in virus classification?
What are the primary factors used in virus classification?
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What defines a naked virus?
What defines a naked virus?
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Which component of a virus is responsible for forming its protective shell?
Which component of a virus is responsible for forming its protective shell?
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When does a virus become enveloped?
When does a virus become enveloped?
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Which nucleic acid configuration can viruses possess?
Which nucleic acid configuration can viruses possess?
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What is the term for the complete complex of nucleic acid and protein in a virus?
What is the term for the complete complex of nucleic acid and protein in a virus?
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What is the primary function of lipopolysaccharides (LPS) in Gram-negative bacteria?
What is the primary function of lipopolysaccharides (LPS) in Gram-negative bacteria?
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Which statement correctly describes the peptidoglycan structure in Gram-positive bacteria?
Which statement correctly describes the peptidoglycan structure in Gram-positive bacteria?
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What role do teichoic acids play in Gram-positive bacteria?
What role do teichoic acids play in Gram-positive bacteria?
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The periplasmic space in Gram-negative bacteria is located between which two structures?
The periplasmic space in Gram-negative bacteria is located between which two structures?
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How does the capsule contribute to the virulence of bacteria?
How does the capsule contribute to the virulence of bacteria?
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Which of the following components is NOT typically found in Gram-positive bacteria?
Which of the following components is NOT typically found in Gram-positive bacteria?
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What distinguishes Gram-positive bacteria from Gram-negative bacteria in terms of cell wall structure?
What distinguishes Gram-positive bacteria from Gram-negative bacteria in terms of cell wall structure?
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Which function is NOT a role of the capsule found in bacteria?
Which function is NOT a role of the capsule found in bacteria?
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Study Notes
Bacterial Classification
- Bacteria are single celled microbes
- Lack a nucleus or membrane bound organelles
- Cell wall is a mixed polymer of hexose sugars (N-acetylglucosamine and N-acetylmuramic acid) and amino acids
- Bacteria are classified according to their cell wall as Gram-positive or Gram-negative.
Gram pattern
- In 1882, Christian Gram devised a bacterial staining method to visualize bacterial cell wall that allowed to differenciate bacteria in two major groups.
- Gram positive bacteria have a thick peptidoglycan layer (20-80nm) external to the cell membrane
- Gram negative bacteria have a thin peptidoglycan layer (5-10nm) overlaid by an outer membrane containing lipopolysaccharides and lipoprotein
Lipopolysaccharide (LPS)
- Conserved structure in all Gram-negative bacteria
- Essential for structural integrity and viability of the bacteria
- Also known as endotoxin because it induces a strong immune response in the host
- Involved in other aspects of bacterial ecology, such as surface adhesion
Other cell wall components
- Teichoic acids: present in Gram positive bacteria, involved in uptake of Mg2+ by the cell
- Teichuronic acids: similar polymers found in capsules or LPS in some Gram negative bacteria
- Other: Lipids, proteins…
Capsule
- External to the cell wall
- Composed of high molecular weight polysaccharides that give a slimy surface
- Very important in virulence, as it protects the microorganism from the host immune system
Nutrition
- Process by which chemical substances (nutrients) are acquired from the environment and used in cellular activities.
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Description
This quiz delves into the fundamentals of bacterial classification, focusing on the key differences between Gram-positive and Gram-negative bacteria. It covers the structural characteristics of bacterial cell walls and the historical context of Gram staining as a method established by Christian Gram in 1882.
