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Questions and Answers
What is the pH range of extremophiles?
What is the pH range of extremophiles?
Which type of bacteria grows in the presence or absence of oxygen?
Which type of bacteria grows in the presence or absence of oxygen?
What is an example of a cave-dwelling bacterium?
What is an example of a cave-dwelling bacterium?
Which bacterium is known to cause ulcers?
Which bacterium is known to cause ulcers?
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What is the main difference between aerobes and anaerobes?
What is the main difference between aerobes and anaerobes?
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Which of the following bacteria is a microaerophile?
Which of the following bacteria is a microaerophile?
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What is an example of a gut bacterium?
What is an example of a gut bacterium?
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Which type of bacteria produces acidic slime?
Which type of bacteria produces acidic slime?
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What is the oxygen requirement for anaerobes?
What is the oxygen requirement for anaerobes?
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Which of the following is not a characteristic of extremophiles?
Which of the following is not a characteristic of extremophiles?
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Study Notes
What are Bacteria?
- Microscopic, single-celled organisms with a diameter of 0.2-2 µm and a length of 1-10 µm
- Prokaryotic organisms with different shapes
- Lack membrane-bound organelles
- Can exist both inside and outside other organisms
- Can survive in extreme habitats, known as the "microbiome"
Microbiome
- Includes all microorganisms in a particular environment
- Encompasses the air microbiome, soil microbiome, water microbiome, and human body microbiome
- Airborne bacteria can be found in bioaerosol, droplets, dust, and particles
- Released from activities of animals, plants, and humans
Bacteria in Humans
- Play a vital role in digestion, immune system function, and overall health
- Beneficial bacteria aid in digestion and immune system function
- Harmless bacteria do not cause harm, while harmful bacteria can cause infections
Characteristics of Life
- Metabolism: convert nutrients into energy for growth and reproduction
- Reproduction: through binary fission
- Response to stimuli: change in pH, temperature, and nutrient scarcity
- Homeostasis: regulation of internal stability and balance
- Evolution: through mutation, gene transfer, and natural selection
- Genetic material: DNA
Fundamentals of Bacteria
- Cell structure: prokaryotic cell with no defined organelles and genetic material in the nucleoid zone
- Ecology and diversity: found everywhere on earth, exhibiting great diversity in morphology, physiology, and ecological role
- Pathogenicity: produce virulent toxins, colonize host tissue, avoid the immune system, and cause infection
Basic Characteristics of Bacteria
- Cell wall: distinct composition
- Cell membrane: extra layer
- Primitive cell structure: no distinct nucleus
- Cell organelles: simple organization
- Ribosome: 70 S type
- DNA gyrase: unique enzyme
- Respiration: aerobic without mitochondria
- Reproduction: multiple methods
- Pilli: sexual reproduction organelles
- Distribution: cosmopolitan, found everywhere
- Feeding dependence: many modes
- Chloroplast: absent
Bacteria Identification
- Based on biochemical tests, such as:
- Catalase: detect hydrogen peroxide breakdown
- Coagulase: detect blood clotting
- Oxidase: detect cytochrome C that transfers electrons to oxygen
- Tryptophanase: detect indole production
- Sugar fermentation: detect fermentation ability to produce acid and gas
Classification of Bacteria
- Based on:
- Shape
- pH
- Oxygen requirement
- Shapes:
- Coccus: spherical or round
- Bacillus: rod-shaped
- Spiral: curve, spiral, or twisted
- Compound shapes:
- Diplo-: divided cells remain in pairs
- Strepto-: divided cells remain in chains
- Tetrad-: divided cells remain in groups of four in two planes
- Sarcinae: divided cells remain in groups of eight in three planes
- Staphylo-: divided cells remain in clusters in multiple planes
Classification Based on pH
- Acidiphiles: pH ≤ 5, e.g., Acidithiobacillus
- Neutrophiles: pH 7, e.g., human pathogens and environmental microbes
- Alkaliphiles: pH > 9, e.g., Bacillus alkalophilus and B. firmus
- Neutrotolerant/Facultative: wide range of pH, e.g., gut bacterium (Escherichia coli)
Classification Based on Oxygen Requirement
- Aerobes: 21% oxygen, e.g., Bacillus, Pseudomonas, Micrococcus, and Staphylococcus
- Facultative anaerobes: grow in presence or absence of oxygen, e.g., Escherichia coli, Pseudomonas aeruginosa, Staphylococcus, Listeria, Salmonella, Shewanella oneidensis, and Yersinia pestis
- Anaerobes: grow in absence of oxygen, e.g., Bacilli, Lactobacilli, Bacteroides, Clostridium, and Staphylococcus
- Microaerophiles: grow in slightly reduced oxygen levels, e.g., Vibrio, Campylobacter, Legionella, Neisseria...
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Description
This quiz covers the basics of bacteria, including their microscopic size, prokaryotic nature, and ability to thrive in extreme habitats. Learn about the characteristics of bacteria and their role in the microbiome.
