Questions and Answers
What are the two types of cellular microorganisms?
Prokaryotic cells have a nuclear body.
False
What is the main constituent of the bacterial cell wall?
Peptidoglycan
The characteristic structure of M.tuberculosis seen in a stain is known as __________.
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Match the following bacterial growth factors with their descriptions:
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What type of acid composition is found in bacterial endospores?
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Gram negative bacteria retain crystal violet stain after a Gram stain procedure.
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Which of the following is a key function of the bacterial capsule?
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What are pili used for in bacteria?
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Which of these is NOT a type of bacterial flagella?
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Endotoxins are proteins released by living bacteria.
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What is the term for bacteria that thrive at low temperatures?
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Which of the following nutrients is essential for bacterial growth?
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Study Notes
Microorganisms
- Microorganisms are classified into acellular (viruses) and cellular organisms (prokaryotes and eukaryotes).
Comparison Between Eukaryotic and Prokaryotic Cells
- Prokaryotes lack a true nucleus, while eukaryotes have a defined nuclear body.
- Prokaryotic cells divide through binary fission; eukaryotic cells divide via mitosis or meiosis.
- Prokaryotes typically have peptidoglycan cell walls; eukaryotic cells may have cellulose or chitin.
- Prokaryotic cytoplasmic membranes are simpler than eukaryotic ones.
- Prokaryotes generally lack membrane-bound organelles, whereas eukaryotes contain them.
- Energy production in prokaryotes occurs in the cytoplasmic membrane; in eukaryotes, it occurs in mitochondria.
- Protein synthesis sites differ; prokaryotes use ribosomes in the cytoplasm, while eukaryotes use ribosomes attached to the endoplasmic reticulum.
Bacterial Cytology
- Cell Wall: Composed mainly of peptidoglycan, providing protection and shape to bacteria. Components like M protein and mycolic acid can enhance pathogenicity.
- Cytoplasmic Membrane: Functions as a selectively permeable barrier.
- Mesosomes: Extensions of the cytoplasmic membrane, serving as sites for chromosome attachment.
- Ribosomes: Essential for protein synthesis.
- Inclusions: Nutrient storage, with examples including metachromatic granules.
- Endospores: Highly resistant resting cells composed of calcium dipicolinate, produced by genera like Bacillus and Clostridium.
- Capsule: Enhances virulence by hindering phagocytosis; can be antigenic based on K antigens.
- Pili (Fimbriae): Include ordinary pili for attachment and sex pili for conjugation.
- Glycocalyx: Can be a capsule (organized) or slime layer (unorganized).
Bacterial Structures
- Flagella: Used for locomotion; classified by arrangements (atrichous, monotrichous, etc.).
- Periplasmic Flagella: Also known as axial filaments, contribute to cell motility.
Bacterial Virulence Factors
- Adherence and antiphagocytic factors, enzymes, and toxins (exotoxins and endotoxins) play significant roles in pathogenicity.
- Exotoxins: Secreted proteins, heat-labile, with specific pharmacological effects.
- Endotoxins: Part of the bacterial cell wall, heat-stable, less immunogenic.
Bacterial Growth Factors
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Nutrients: Essential elements like carbon, nitrogen, and minerals are necessary for growth.
- Some organisms are halophilic, requiring high salt concentrations.
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Oxygen and Carbon Dioxide:
- Obligate aerobe: Requires oxygen.
- Obligate anaerobe: Grows in absence of oxygen.
- Facultative anaerobe: Can switch between aerobic and anaerobic respiration.
- Microaerophilic: Requires low oxygen levels.
- Capnophilic: Prefers elevated CO2 levels.
- Temperature: Bacteria can be classified as psychrophilic, mesophilic, or thermophilic based on optimal temperature ranges.
- pH: Most bacteria thrive in neutral or slightly alkaline conditions; some extremes include acidophiles and alkaliphiles.
Growth Cycle and Culture Media
- Understanding bacterial growth cycles is essential for proper culturing and experimentation.
- Nutrient media formulation is critical for cultivating specific microorganisms.
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Description
This quiz covers fundamental concepts in microbiology, focusing on the comparison between prokaryotic and eukaryotic cells. It delves into their structures, functions, and differences, providing a clear understanding of cellular biology. Perfect for students looking to review key concepts in their microbiology studies.
