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Questions and Answers
Which characteristic is true about all archaea?
Which characteristic is true about all archaea?
Which of the following is true about gram-positive bacteria?
Which of the following is true about gram-positive bacteria?
What distinguishes proteobacteria from non-proteobacteria?
What distinguishes proteobacteria from non-proteobacteria?
What is a significant feature of bacteroides bacteria?
What is a significant feature of bacteroides bacteria?
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Which of the following statements about cyanobacteria is correct?
Which of the following statements about cyanobacteria is correct?
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Which bacterial group is known for having a high number of pathogenic species?
Which bacterial group is known for having a high number of pathogenic species?
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What is a common trait of extremophiles?
What is a common trait of extremophiles?
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Which of the following best describes the classification of spirochetes?
Which of the following best describes the classification of spirochetes?
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Which of the following bacteria is responsible for syphilis?
Which of the following bacteria is responsible for syphilis?
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Which type of bacteria are Bacteroides classified as?
Which type of bacteria are Bacteroides classified as?
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What unique feature allows spirochetes to move through tissues?
What unique feature allows spirochetes to move through tissues?
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Which electron donor do purple sulfur bacteria use for photosynthesis?
Which electron donor do purple sulfur bacteria use for photosynthesis?
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What is a characteristic of purple non-sulfur bacteria?
What is a characteristic of purple non-sulfur bacteria?
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Which of the following diseases is NOT caused by spirochetes?
Which of the following diseases is NOT caused by spirochetes?
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What role do Bacteroides play in the human colon?
What role do Bacteroides play in the human colon?
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What common characteristic do all obligate anaerobes share?
What common characteristic do all obligate anaerobes share?
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What type of bacteria are Staphylococcus and Streptococcus classified as?
What type of bacteria are Staphylococcus and Streptococcus classified as?
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Which of the following is an example of a pathogenic streptococcus?
Which of the following is an example of a pathogenic streptococcus?
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Which hemolytic activity is displayed by Staphylococcus aureus?
Which hemolytic activity is displayed by Staphylococcus aureus?
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What type of toxin does S. aureus produce?
What type of toxin does S. aureus produce?
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What method is used to categorize species of Enterococcus, Streptococcus, and Staphylococcus?
What method is used to categorize species of Enterococcus, Streptococcus, and Staphylococcus?
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Which of the following describes Actinobacteria?
Which of the following describes Actinobacteria?
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What is a distinguishing feature of the cell wall in Actinobacteria?
What is a distinguishing feature of the cell wall in Actinobacteria?
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Which enzyme produced by pathogenic streptococci can lyse red blood cells?
Which enzyme produced by pathogenic streptococci can lyse red blood cells?
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What is the infective form of Chlamydia known as an elementary body primarily characterized by?
What is the infective form of Chlamydia known as an elementary body primarily characterized by?
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Which of the following correctly describes the prokaryotic domain composed of organisms that can tolerate extreme environments?
Which of the following correctly describes the prokaryotic domain composed of organisms that can tolerate extreme environments?
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What method do spirochetes primarily use for motility?
What method do spirochetes primarily use for motility?
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What distinguishes Chlamydophila psittaci in its pathogenicity?
What distinguishes Chlamydophila psittaci in its pathogenicity?
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Which group of bacteria is recognized for their ability to fix nitrogen in the ecosystem?
Which group of bacteria is recognized for their ability to fix nitrogen in the ecosystem?
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Which of the following lists groups of bacteria based on their photosynthetic capabilities?
Which of the following lists groups of bacteria based on their photosynthetic capabilities?
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What is a key characteristic of the family Enterobacteriaceae?
What is a key characteristic of the family Enterobacteriaceae?
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What is the primary electron donor used by green sulfur bacteria during their photosynthesis?
What is the primary electron donor used by green sulfur bacteria during their photosynthesis?
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Which of the following accurately describes cyanobacteria?
Which of the following accurately describes cyanobacteria?
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In terms of bacterial classification, what defines proteobacteria?
In terms of bacterial classification, what defines proteobacteria?
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What type of disease does Corynebacterium diphtheriae cause?
What type of disease does Corynebacterium diphtheriae cause?
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Which organism is known for producing most antibiotics?
Which organism is known for producing most antibiotics?
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Which characteristic is associated with Mycobacterium tuberculosis?
Which characteristic is associated with Mycobacterium tuberculosis?
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What kind of environment do extreme halophiles require?
What kind of environment do extreme halophiles require?
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Which of the following statements about Mycobacterium leprae is correct?
Which of the following statements about Mycobacterium leprae is correct?
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Which type of bacteria are classified as anaerobic extremophiles?
Which type of bacteria are classified as anaerobic extremophiles?
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What type of cell wall do archaea have?
What type of cell wall do archaea have?
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What distinguishes Streptomyces from other actinobacteria?
What distinguishes Streptomyces from other actinobacteria?
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Study Notes
Prokaryote Classification
- Bacteria and Archaea are the two domains of prokaryotes.
- Bacteria were the first living organisms.
- Archaea evolved in a pre-oxygen atmosphere.
- Gram-negative bacteria evolved first, then gram-positive bacteria.
- All archaea are extremophiles and obligate anaerobes.
- Bacteria can be aerobic or anaerobic.
- Bacteria have a wider range of environmental niches.
- Archaea, unlike bacteria, are non-pathogenic.
Bacterial Shapes and Arrangements
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Major Bacterial Groups:
- Bacteroides: Gram-negative rods, obligate anaerobes.
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Photosynthetic Bacteria:
- Anoxygenic: Sulfur/non-sulfur (purple/green), use an electron donor that is not water.
- Cyanobacteria: Oxygenic, use water as an electron donor and produce oxygen.
- Spirochetes: Coiled, move via axial filaments (endoflagella), many are pathogenic.
- Chlamydias: Intracellular parasitic bacteria.
- Gram-Positive Bacteria: Latest evolving bacteria, divided into the Firmicutes and Actinobacteria phyla.
Non-Proteobacteria
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Bacteroides:
- Bacteroides fragilis: Gram-negative rod, obligate anaerobe, normal colon microbiota.
- First bacteria to evolve.
- Major inhabitants of the human colon.
- Ferment indigestible sugar derivatives.
- Break down toxins.
- Produce communication molecules (polysaccharide A) that direct the innate immune response.
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Photosynthetic Bacteria:
- Anoxygenic: Carry out photosynthesis using a non-water electron donor.
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Purple Sulfur Bacteria:
- Use H2S as the electron donor.
- Produce sulfides instead of oxygen.
- Absorb higher energy wavelengths than green sulfur bacteria.
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Purple Non-Sulfur Bacteria:
- Use organic hydrogen sources as the electron donor.
- Absorb higher energy wavelengths than green non-sulfur bacteria.
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Green Sulfur Bacteria:
- Use H2S as the electron donor for photosynthesis.
- Produce sulfides instead of oxygen.
- Aerotolerant anaerobes.
- Absorb light at lower wavelengths than purple sulfur bacteria.
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Green Non-Sulfur Bacteria:
- Use organic hydrogen sources as the electron donor.
- Aerotolerant anaerobes.
- Absorb lower wavelengths than purple non-sulfur bacteria.
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Spirochetes:
- Spiral-shaped bacteria.
- Coiled and move via axial filaments.
- Many are pathogenic:
- Treponema pallidum: Causes syphilis.
- Treponema pertenue: Causes yaws.
- Treponema pallidum subspecies endemicum: Causes bejel.
- Can literally "drill" through skin and tissues.
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Chlamydia:
- Obligate intracellular parasites.
- Diminished or no cell wall.
- Grow intracellularly.
- Elementary Bodies: The "endospore-like" infective form.
- Reticulate Bodies: The intracellular replicative, cellular form.
- Chlamydia trachomatis: Causes pelvic inflammatory disease and urethritis.
- Chlamydophila psittaci: Causes respiratory psittacosis (pneumonia).
Proteobacteria
- All gram-negative bacteria.
- Oxygen-tolerant.
- Most are obligate aerobes or facultative anaerobes.
- Great diversity (over 30% of known bacteria).
- The largest bacterial phyla.
- Diverse metabolisms, including heterotrophs, lithotrophs, and photosynthesizers.
- Five classes: alpha, beta, gamma, delta, epsilon.
- Include oxygenic and anoxygenic photosynthetic bacteria:
- Cyanobacteria: Oxygenic, use water as the electron donor and produce oxygen.
- Green Sulfur/Non-Sulfur Bacteria: Anoxygenic, use a non-water electron donor.
- Many pathogenic species (Shigella, Salmonella).
- Contain nitrogen-fixing species.
Cyanobacteria
- Also known as "blue-green algae."
- Oxygenic photosynthetic bacteria.
- Use water as the electron donor and produce oxygen.
- Fix the majority of carbon dioxide in the ecosystem.
- Many contain heterocysts that fix nitrogen.
- Many contain gas vesicles that provide buoyancy.
- Can be unicellular or filamentous, and colonial.
Enterobacteriaceae
- A family of enteric (gut) gram-negative rods.
- All are facultative anaerobes and motile.
- E. coli, an example, uses actin-like filaments to propel itself through host cytoplasm and invade neighboring cells.
Gram-Positive Bacteria: Firmicutes
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Low "GC content" gram-positive bacteria.
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Streptococcus:
- Coccus in chains.
- Produce enzymes that destroy tissues.
- Pathogenic streptococci include:
- Streptococcus pneumoniae: Causes pneumonia.
- Streptococcus mutans: Causes dental caries.
- Beta-hemolytic streptococci hemolyze blood.
- Streptococcus pyogenes: Causes strep throat and scarlet fever.
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Staphylococcus:
- Grape-like clusters.
- Often antibiotic-resistant.
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Staphylococcus aureus: Causes wound and skin infections, produces four types of toxins:
- Hemolysin: Lyses red blood cells.
- Leukotoxin: Lyses white blood cells.
- Enterotoxin: Intestinal toxin.
- Toxic-shock syndrome toxin-1: Can cause sepsis.
- Species of Enterococcus, Streptococcus, and Staphylococcus are distinguished by their level of hemolysis on blood agar plates.
Gram-Positive Bacteria: Actinobacteria
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High "GC content" gram-positive bacteria.
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A broad group, including antibiotic producers, decomposers, and pathogens.
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Cell wall includes unusual cell wall lipids, such as mycolic acid.
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Most stain with acid-fast stain.
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Corynebacterium:
- Corynebacterium diphtheriae: Causes diphtheria, characterized by difficulty breathing, heart failure, and paralysis.
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Propionibacterium:
- Produces propionic acid.
- Propionibacterium acnes: Causes acne.
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Gardnerella:
- Gardnerella vaginalis: Causes vaginitis.
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Streptomyces:
- The largest genus of Actinobacteria.
- Most produce endospores.
- Isolated from soil.
- Produce the majority of antibiotics.
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Mycobacterium:
- Acid-fast bacteria.
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Mycobacterium tuberculosis:
- Mycolic acid cell wall: Makes it an intracellular pathogen.
- Highly infective obligate aerobe: Infects the lungs.
- Highly contagious: Spread through aerosol transmission.
- Many infections are antibiotic resistant.
-
Mycobacterium leprae:
- Mycolic acid cell wall: Makes it an intracellular pathogen.
- Causes leprosy: Infects peripheral nerves.
- Targets skin, eyes, nose, and mouth.
- Not highly contagious: Spread through direct contact.
Archaea
- Often referred to as "extreme bacteria," all are anaerobic extremophiles.
- Unique cell wall: Pseudomurein, which lacks peptidoglycan.
- Heterotrophic: Require organic and inorganic carbon for metabolism.
- Non-pathogenic: No species has been shown to cause human disease.
- Environmental niche: Extreme environments, including the human gut.
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Extremophiles:
- Extreme Halophiles: Require a salt concentration of over 25%.
- Thermophiles: Require a growth temperature over 80°C.
- Psychrophiles: Require low temperatures.
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Description
Test your knowledge about the two domains of prokaryotes: Bacteria and Archaea. Explore the evolution, characteristics, and classification of various bacterial groups and their distinctive features. This quiz covers topics such as bacterial shapes, arrangements, and metabolic types.
