Questions and Answers
What are the characteristics of bacteria?
Simple prokaryotic cells that function metabolically and reproduce, do not have cell walls, and have a complex cell wall structure that enables them to live in different environments.
What is normal flora?
Bacteria that normally inhabit the body and live cooperatively with it, usually not causing disease.
What is a bacterial culture?
A bacterial culture can be identified based on its specific growth requirements, and culture media can be created to encourage the growth of some bacteria and inhibit others.
What are the major groups of bacteria based on shape?
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What are the major groups of bacteria based on arrangement?
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What is the function of the cell wall of bacteria?
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What is the function of the cell membrane of bacteria?
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What is the function of the capsule or slime layer of bacteria?
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What is the function of flagella and pili of bacteria?
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What is the function of the cytoplasm of bacteria?
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What is the function of the endospore of bacteria?
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What is Gram-staining?
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What are the characteristics of Gram-positive bacteria?
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What are the characteristics of Gram-negative bacteria?
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What are exotoxins?
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What are endotoxins?
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What are enzymes?
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What are obligate aerobes?
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What are obligate anaerobes?
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What are aerotolerant anaerobes?
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Study Notes
Characteristics of Bacteria
- Prokaryotic cells with simple structure that metabolize and reproduce.
- Lack cell walls; DNA is not enclosed in a true nucleus, but exists in a nucleoid.
- Possess complex cell walls, enabling survival in diverse environments.
Normal Flora
- Bacteria that habitually live in the body, fostering a cooperative relationship.
- Essential for maintaining a healthy bacterial balance, preventing pathogen colonization.
Bacterial Culture
- Identified by specific growth needs; culture media can be tailored to promote certain bacteria while inhibiting others.
Major Groups of Bacteria (Shape)
- Bacilli: rod-shaped bacteria.
- Spiral: includes spirochetes and spirilla, appearing coiled or wavy.
- Cocci: spherical-shaped bacteria.
Major Groups of Bacteria (Arrangement)
- Diplo: pairs of bacteria.
- Strepto: chains of bacteria.
- Staphylo: clusters resembling grapes.
- Tetrads: groups of four cocci in a square.
- Palisade: rod-shaped bacteria aligning in stacks.
Cell Wall of Bacteria
- Rigid structure providing protection, maintaining internal contents, and determining shape.
Cell Membrane of Bacteria
- Located within the cell wall; semipermeable, regulating nutrient and material exchange.
- Site of various metabolic processes.
Capsule or Slime Layer of Bacteria
- Not universally found; external to the cell wall, offering additional protection.
Flagella and Pili of Bacteria
- Flagella: long, rotating structures providing motility to certain species.
- Pili: hair-like structures aiding in bacterial attachment and DNA transfer between bacteria.
Cytoplasm of Bacteria
- Comprises ribosomes, RNA, and a single long DNA strand (nucleoid), along with plasmids and other cellular components.
Endospore of Bacteria
- Special structure formed by some bacteria to withstand unfavorable conditions.
- Strong protein coat surrounds the bacterial DNA, protecting it in a dormant state until conditions improve.
Gram-Staining
- Primary method for distinguishing bacterial types based on cell wall characteristics.
Gram-Positive Bacteria
- Characterized by a thick peptidoglycan layer; stains purple-blue.
- Contains teichoic acids and minimal periplasmic space; more susceptible to antibiotics.
Gram-Negative Bacteria
- Features a thinner peptidoglycan layer and a complex outer membrane; stains pink.
- Lacks teichoic acids, has a large periplasmic space, and is generally harder to treat with antibiotics.
Exotoxins
- Toxic substances typically associated with gram-positive bacteria, impacting body functions and stimulating immunity.
Endotoxins
- Found in gram-negative bacteria's cell wall; released upon cell lysis, often evoking immune responses.
Enzymes
- Produced by bacteria to damage host tissues or facilitate tissue invasion by degrading structural components.
Obligate Aerobes
- Require oxygen for survival and energy production through aerobic respiration.
Obligate Anaerobes
- Thrive in oxygen-free environments; energy generated via anaerobic respiration or fermentation.
Aerotolerant Anaerobes
- Cannot utilize oxygen for energy but can grow in its presence, relying on fermentation processes.
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Enhance your understanding of pathogens with these flashcards. Each card covers essential characteristics of bacteria and the role of normal flora in the human body. Perfect for students studying microbiology or health sciences.