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What is the primary component of the Gram positive bacterial cell wall that contributes to its structural integrity?
What is the primary component of the Gram positive bacterial cell wall that contributes to its structural integrity?
The primary component is the peptidoglycan layer, which constitutes about 50% of the cell wall.
Describe the significance of lipopolysaccharide (LPS) in the cell wall of Gram negative bacteria.
Describe the significance of lipopolysaccharide (LPS) in the cell wall of Gram negative bacteria.
LPS acts as an endotoxin and plays a role in the structural integrity of the outer membrane.
How does teichoic acid contribute to the properties of Gram positive bacterial cell walls?
How does teichoic acid contribute to the properties of Gram positive bacterial cell walls?
Teichoic acid provides rigidity and is involved in cell wall maintenance and regulation of autolysin activity.
What role does the periplasmic space play in Gram negative bacteria?
What role does the periplasmic space play in Gram negative bacteria?
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Why is peptidoglycan considered a target for antibiotics like penicillins and cephalosporins?
Why is peptidoglycan considered a target for antibiotics like penicillins and cephalosporins?
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What is the primary function of ribosomes in bacterial cells?
What is the primary function of ribosomes in bacterial cells?
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How do capsules contribute to bacterial virulence?
How do capsules contribute to bacterial virulence?
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What is the structure that facilitates bacterial motility?
What is the structure that facilitates bacterial motility?
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Explain the role of pili in bacterial cells.
Explain the role of pili in bacterial cells.
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Describe the structure and significance of plasmids in bacteria.
Describe the structure and significance of plasmids in bacteria.
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What distinguishes the cytoplasmic membrane of bacterial cells?
What distinguishes the cytoplasmic membrane of bacterial cells?
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What type of bacterial structure is not stained by Gram stain?
What type of bacterial structure is not stained by Gram stain?
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Identify the type of DNA that is typically found in bacterial cells.
Identify the type of DNA that is typically found in bacterial cells.
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What are two primary functions of the bacterial cell wall?
What are two primary functions of the bacterial cell wall?
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Explain the structure of lipopolysaccharides (LPS) in gram-negative bacteria.
Explain the structure of lipopolysaccharides (LPS) in gram-negative bacteria.
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What environmental conditions lead to spore formation in gram-positive bacteria?
What environmental conditions lead to spore formation in gram-positive bacteria?
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Why are bacterial spores highly resistant to sterilization techniques?
Why are bacterial spores highly resistant to sterilization techniques?
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Which genera of bacteria are known for spore formation?
Which genera of bacteria are known for spore formation?
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What is the significance of autoclaving at 121 °C for sterilizing spores?
What is the significance of autoclaving at 121 °C for sterilizing spores?
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Assess the statement: 'Bacterial spores are essential bacterial structures.' True or False?
Assess the statement: 'Bacterial spores are essential bacterial structures.' True or False?
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What part of lipopolysaccharides is responsible for the antigenic properties of the bacterial cell wall?
What part of lipopolysaccharides is responsible for the antigenic properties of the bacterial cell wall?
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What is the primary component that distinguishes prokaryotic cell walls from eukaryotic cell walls?
What is the primary component that distinguishes prokaryotic cell walls from eukaryotic cell walls?
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How do prokaryotic cells replicate, and how does this differ from eukaryotic cell replication?
How do prokaryotic cells replicate, and how does this differ from eukaryotic cell replication?
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What are the characteristics of Gram-negative bacteria in terms of their appearance after staining?
What are the characteristics of Gram-negative bacteria in terms of their appearance after staining?
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List the three main shapes of bacteria and give an example of each.
List the three main shapes of bacteria and give an example of each.
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What is the significance of bacterial endospores in the medical field?
What is the significance of bacterial endospores in the medical field?
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Which type of ribosomes are found in prokaryotic cells, and how do they differ from ribosomes in eukaryotic cells?
Which type of ribosomes are found in prokaryotic cells, and how do they differ from ribosomes in eukaryotic cells?
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Describe how the arrangement of cocci bacteria is determined.
Describe how the arrangement of cocci bacteria is determined.
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What staining method would you use to identify Mycobacteria and why?
What staining method would you use to identify Mycobacteria and why?
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What type of organism does bacteriology focus on, and what are the broader fields of microbiology?
What type of organism does bacteriology focus on, and what are the broader fields of microbiology?
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Explain the term 'Gram reaction' and its importance in microbiology.
Explain the term 'Gram reaction' and its importance in microbiology.
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Study Notes
Bacterial Structure
- Bacteria are single-celled microorganisms, microscopic
- Classified by Gram stain (Gram-positive or Gram-negative)
- Gram-positive bacteria stain purple, Gram-negative stain pink.
- There are different shapes for bacteria (cocci, bacilli, spirilla, vibrios).
Types of Bacteria
- Cocci: Spherical bacteria
- Bacilli: Rod-shaped bacteria
- Spirilla: Spiral-shaped bacteria
- Vibrios: Curved rod-shaped bacteria
Bacterial Cell Structure (Outside to Inside)
- Flagella: Organ of motility, made of flagellin protein
- Different arrangements of flagella exist (monotrichous, lophotrichous, peritrichous, amphitrichous)
- Pili/Fimbriae: Attachment structures, often involved in bacterial adhesion to surfaces or conjugation (transferring genetic material between bacteria.)
- Capsule/Glycocalyx: Outer layer, helps protect and attach or mask attachment sites, not stained by Gram stain, not found in all bacteria, made of polysaccharide but some polypeptide
- Cell Wall: Structurally important, differs between Gram-positive and Gram-negative bacteria, essential structural component that maintains shape and protects the cell
- Cell Membrane: Semi-permeable membrane, involved in transport of various materials, essential
- DNA (Chromosome): Single circular chromosome (no nuclear membrane), essential genetic material for basic functions
- Plasmid: Extra-chromosomal circular DNA, can carry additional genetic information (not essential)
- Ribosomes: 70S ribosomes - involved in protein synthesis (essential)
- Food Granules: Storage for nutrients (not always present)
- Spores: Highly resistant resting forms under unfavourable conditions, essential in survival under harsh conditions
Bacterial Cell Wall
- Gram-positive: Thick peptidoglycan layer (40 layers), teichoic acid
- Gram-negative: Thin peptidoglycan layer (2 layers), outer membrane (liposaccharides, proteins) , Lipid A (endotoxin)
- Peptidoglycan is the major target for many antibiotics.
- Peptidoglycan is made of disaccharide units and tetrapeptide chain
Prokaryotes vs. Eukaryotes
- Key difference is the presence or absence of a nucleus/membrane-bound organelles.
Gram-Negative Cell Wall: LPS (Lipopolysaccharides)
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LPS is the outer component
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Lipid A part is endotoxin - Released into blood upon bacterial death, causing fever or shock
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Somatic O-antigen is the antigenic part.
Spores
- Highly resistant, resting forms of some Gram-positive bacteria, formed due to unfavourable conditions
- Resistance factors: thick cortex, calcium dipicolinate,
- Spore-forming bacteria are important for survival in extreme conditions.
- Autoclaving needed to destroy/kill spores
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