Questions and Answers
Which of the following Gram-Negative Bacteria is Oxidase +?
Which of the following Gram-Negative Bacteria is Lactose +?
What is the shape of Vibrio?
Which of the following Gram-Negative Bacteria grows at 42°C in alkaline media?
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Which Gram-Negative Bacteria is Oxidase -?
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Which of the following Gram-Negative Bacteria is a Diplococci?
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What characterizes eukaryotic cells?
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What is the main focus of bacteriology?
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What is the size range of objects that are too small to be visible with the naked eye?
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Which of the following is NOT a type of eukaryote?
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What is the term for the study of all living organisms that are too small to be visible with the naked eye?
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Which of the following is a type of acellular organism?
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What is the function of Lipid A in the lipopolysaccharide (LPS) of Gram-negative bacteria?
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What is the component of peptidoglycan that is responsible for its cross-linking?
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What is the target of β-lactam drugs, including penicillin?
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How many ATP molecules are generated during the metabolism of one glucose molecule in prokaryotes?
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What is the main difference between the metabolism of eukaryotes and prokaryotes?
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What is the characteristic of Gram-positive bacteria?
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Which of the following features is characteristic of eukaryotic cells?
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What is the purpose of the Gram stain method in microbiology?
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What is the function of the peptidoglycan layer in Gram-positive bacteria?
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What is the main component of the outer membrane in Gram-negative bacteria?
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What is the primary function of porins in Gram-negative bacteria?
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Which of the following is a characteristic of Gram-positive bacteria?
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What is microbiology?
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What is bacteriology?
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Eukaryotes are single-celled organisms that have a distinct nucleus with a membrane.
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What is the main difference between prokaryotes and eukaryotes?
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What is the purpose of Gram staining?
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What is the function of peptidoglycan in bacterial cell walls?
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What is the primary function of lipopolysaccharides (LPS) in Gram-negative bacteria?
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What is the role of transpeptidases in bacterial cell wall synthesis?
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What is the significance of ATP production in microbial metabolism?
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Match the following Gram-positive bacteria with their characteristic shapes:
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Match the following Gram-negative bacteria with their characteristic features:
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Study Notes
Bacteriology
- Eukaryotes are organisms with cells that have a nucleus enclosed within a nuclear envelope.
- Prokaryotes are single-celled organisms that lack a distinct nucleus with a membrane and other specialized organelles.
Microbiology
- Microbiology is the study of all living organisms that are too small to be visible with the naked eye.
- Bacteriology is the study of bacteria.
Scope of Microbiology
- Microbiology encompasses the study of cellular organisms (bacteria, archaea, fungi, algae, protozoa, and helminths) and acellular entities (viruses, viroids, and prions).
Prokaryotes vs. Eukaryotes
- Prokaryotes lack a true nucleus and membrane-bound organelles.
- Eukaryotes have a true nucleus and membrane-bound organelles.
Gram-Negative Bacteria
- Gram-negative bacteria have a thin peptidoglycan layer and an outer membrane containing lipopolysaccharides (endotoxins).
- Examples of Gram-negative bacteria include Hemophilus, Bartonella, Pasteurella, Neisseria, Francisella, and Escherichia coli.
Bacterial Structure
- Prokaryotes have a peptidoglycan (murein) layer in their cell wall, composed of repeating units of N-acetylmuramic acid and N-acetylglucosamine.
- The peptidoglycan layer is cross-linked by trans-peptide bridges.
Bacterial Replication
- Cell wall targeting involves the incorporation of peptidoglycan monomers into the existing cell wall matrix, catalyzed by transpeptidases or penicillin-binding proteins (PBPs).
- PBPs are major drug targets for β-lactam antibiotics, including penicillin.
Microbial Metabolism
- Metabolism is the powerhouse of organisms, generating energy and synthesizing molecules.
- Prokaryotes generate 38 ATP, while eukaryotes generate 36 ATP.
Industrial and Laboratory Use of Microbial Metabolism
- Microbial metabolism is used in industrial processes, such as biofuel production, and in laboratory research, such as protein production.
Gram-Positive Bacteria
- Gram-positive bacteria have a thick peptidoglycan layer and teichoic acid.
- Examples of Gram-positive bacteria include Bacillus, Listeria, Clostridium, and Streptococcus.
Gram Stain Method
- Gram staining is a method of classifying bacteria based on their shape and color.
- The process involves heat fixing bacteria, staining with crystal violet, applying iodine, de-staining with alcohol, and counter-staining with Pink Safranin.
Gram Stain and Peptidoglycan
- The peptidoglycan layer of Gram-positive bacteria retains the crystal violet stain, while Gram-negative bacteria do not.
Bacterial Cell Structure
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Gram-positive bacteria have a thick peptidoglycan layer, teichoic acid, and lipoteichoic acid.
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Gram-negative bacteria have a thin peptidoglycan layer, an outer membrane, porins, and lipopolysaccharides.### Basic Bacteriology
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Eukaryotes are organisms whose cells have a nucleus enclosed within a nuclear envelope.
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Prokaryotes are single-celled organisms that lack a distinct nucleus with a membrane and other specialized organelles.
Microbiology and Bacteriology
- Microbiology is the study of all living organisms that are too small to be visible with the naked eye.
- Bacteriology is the study of bacteria.
Scope of Microbiology
- Cellular: Prokaryotes (bacteria, archaea), Eukaryotes (fungi, algae, protozoa, helminths)
- Acellular: Viruses, viroids, prions
Prokaryotes vs. Eukaryotes
- Prokaryotes: • 70s Ribosome (50s and 30s subunits) • Single circular genome • Plasmids (e.g., antimicrobial resistance genes) • No membrane-bound organelles
- Eukaryotes: • 80s Ribosome (60s and 40s subunits) • Multiple chromosomes • Linear genome • Membrane-bound organelles (e.g., nucleus, ER)
Bacterial Structure
- Cell morphology helps classify bacteria
- Gram staining pattern is also used for classification: • Gram-Positive • Gram-Negative • Atypicals
Gram Stain Method
- Bacteria are classified by shape and color using Gram stain procedure
- Steps: • Heat fix bacteria on a glass slide • Stain bacteria with crystal violet • Apply iodine as a mordant to the crystal violet • De-stain bacteria with alcohol • Counter-stain with Pink Safranin
Gram Stain and Peptidoglycan
- Gram Positive: Peptidoglycan layer retains the crystal violet of the Gram stain
- Gram Negative: Thin peptidoglycan layer, outer membrane, porins, and lipopolysaccharide
Bacterial Cell Structure
- Gram Positive Features: • Thick peptidoglycan layer • Teichoic acid • LipoTeichoic acid
- Gram Negative Features: • Thin peptidoglycan layer • Outer membrane • Porins • Lipopolysaccharide (LPS)
Gram-Negative Cell Wall: LPS
- LPS is part of the outer membrane
- Only found on Gram-negative bacteria
- LPS has 3 units: • "O" antigen (polysaccharide, somatic antigen for species identification) • Core polysaccharide • Lipid A (toxic effect, triggers inflammation leading to sepsis)
Cell Wall - Peptidoglycan
- Peptidoglycan monomer is composed of: • NAM (n-acetylmuramic acid) • NAG (n-acetylglucosamine) • Pentapeptide chain (5 amino acids)
- Peptidoglycan layer is composed of repeating subunits of NAG and NAM, crosslinked by sugars and trans-peptide bridges
Cell Wall Targeting
- Transpeptidases or Penicillin-Binding Proteins (PBPs) catalyze the incorporation of the monomer into the existing peptidoglycan wall matrix
- PBPs are major drug targets for β-lactam drugs, including penicillin
Microbial Metabolism
- Metabolism: Powerhouse of organisms
- 36 ATP (Eukaryotes) vs. 38 ATP (Prokaryotes)
- Examples of microbial metabolism: • Industrial use • Laboratory use
Human Pathogens
- Gram-Positive Bacteria: • Bacilli (e.g., Listeria, Bacillus) • Cocci (e.g., Streptococcus, Staphylococcus)
- Gram-Negative Bacteria: • Diplococci (e.g., Neisseria) • Coccobacilli (e.g., Hemophilus) • Bacilli (e.g., Escherichia coli, Klebsiella) • Comma-shaped (e.g., Vibrio, Helicobacter)
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Description
This quiz covers the basics of bacteriology, focusing on the differences between eukaryotes and prokaryotes. Learn about the characteristics of these cell types and test your knowledge.
