Bacterial Phyla and Evolutionary Relationships
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Questions and Answers

What is the distinctive feature of spirochaetes?

  • Straight rod-shaped bacteria
  • Spherical cells with flagella on the surface
  • Tightly coiled cells enclosed by a sheath (correct)
  • Spore-forming bacteria with thick peptidoglycan
  • Which of the following diseases is caused by Borrelia burgdorferi?

  • Trachoma
  • Lyme disease (correct)
  • Botulism
  • Pneumonia
  • What type of pathogens are chlamydiae classified as?

  • Zoonotic pathogens
  • Facultative bacteria
  • Obligate intracellular pathogens (correct)
  • Obligate anaerobes
  • What contributes to the evolution of new pathogens in zoonotic hosts?

    <p>Recombination with animal microbiota</p> Signup and view all the answers

    What does the phylum Firmicutes derive its name from?

    <p>Thick peptidoglycan</p> Signup and view all the answers

    Which Clostridium species is known for causing botulism?

    <p>C. Botulinum</p> Signup and view all the answers

    Where did some genes causing antibiotic resistance originate?

    <p>Natural environments</p> Signup and view all the answers

    What type of growth environment do Bacillus species prefer?

    <p>Aerobic respiration</p> Signup and view all the answers

    What is a primary characteristic of all organisms in the phylum Proteobacteria?

    <p>They are all gram negative.</p> Signup and view all the answers

    What is the primary function of the outer membrane in gram-negative bacteria?

    <p>To protect against host defenses and antibiotics.</p> Signup and view all the answers

    Which family of Proteobacteria primarily appears as rod-shaped bacteria?

    <p>Enterobacteriaceae</p> Signup and view all the answers

    How can bacteria in the Enterobacteriaceae family be distinguished?

    <p>By a variety of biochemical tests.</p> Signup and view all the answers

    What type of environments do facultative anaerobic rods typically inhabit?

    <p>In human or animal digestive tracts or in water bodies.</p> Signup and view all the answers

    What is a defining feature of Pseudomonas species?

    <p>They require a terminal electron acceptor to generate energy.</p> Signup and view all the answers

    Which bacterium is recognized as a key vehicle for biotechnology and can cause intestinal and bladder infections?

    <p>Escherichia coli</p> Signup and view all the answers

    What impact does the formation of biofilms by certain bacterial species have?

    <p>It enhances their resistance to antibiotics.</p> Signup and view all the answers

    Which bacterium is known to cause anthrax?

    <p>Bacillus anthracis</p> Signup and view all the answers

    Which of the following bacteria are resistant to most antibiotics?

    <p>Clostridiodes difficile</p> Signup and view all the answers

    What disease does Clostridium botulinum primarily cause?

    <p>Botulism</p> Signup and view all the answers

    Which organism is characterized by bulging spores and causes intestinal disease?

    <p>Clostridiodes difficile</p> Signup and view all the answers

    What type of bacteria are Enterococcus spp. classified as?

    <p>Cocci</p> Signup and view all the answers

    What do Lactobacillus and Lactococcus spp. predominantly produce?

    <p>Yogurt and cheese</p> Signup and view all the answers

    What characteristic is true about Clostridium spores in the environment?

    <p>They can survive in anaerobic conditions.</p> Signup and view all the answers

    Which of the following is commonly treated with Vancomycin?

    <p>Clostridiodes difficile</p> Signup and view all the answers

    What are the characteristics of endospores produced by Firmicutes?

    <p>They can survive harsh conditions for long periods.</p> Signup and view all the answers

    Which of the following statements about Actinobacteria is true?

    <p>They possess a high 'G+C' content and can produce antibiotics.</p> Signup and view all the answers

    What is a defining feature of Bacteroidetes?

    <p>They include mostly obligate anaerobes that are Gram-negative rods.</p> Signup and view all the answers

    How are evolutionary relatedness among bacteria assessed?

    <p>Through the comparison of 16S rRNA gene sequences.</p> Signup and view all the answers

    Which phyla are classified as Gram-positive bacteria?

    <p>Firmicutes and Actinobacteria.</p> Signup and view all the answers

    What type of metabolism can Proteobacteria exhibit?

    <p>They have a diverse range of metabolic capabilities.</p> Signup and view all the answers

    What happens to the mother cell after it releases a mature endospore?

    <p>It disintegrates after releasing the endospore.</p> Signup and view all the answers

    Which of the following is a function of Bacteroides species in the human gut?

    <p>They help in the digestion of food.</p> Signup and view all the answers

    What are the two developmental stages of Chlamydiae?

    <p>Elementary bodies and reticulate bodies</p> Signup and view all the answers

    What role does the elementary body of Chlamydiae play in infection?

    <p>It is metabolically inert and must transform inside host cells</p> Signup and view all the answers

    What is a consequence of persistent infection with C. Trachomatis?

    <p>Pelvic inflammatory disease</p> Signup and view all the answers

    How do Chlamydiae ensure they can infect new cells?

    <p>By transforming to elementary bodies before exiting the host</p> Signup and view all the answers

    Which of the following describes the outer membrane of Chlamydiae?

    <p>It is tough and provides osmotic stability</p> Signup and view all the answers

    Which disease can be caused by Chlamydia pneumoniae?

    <p>Heart disease</p> Signup and view all the answers

    What can happen without treatment for persistent Chlamydiae infection?

    <p>Inflammation leading to permanent adhesions</p> Signup and view all the answers

    Which characteristic is NOT true about Chlamydiae?

    <p>They can survive independently outside a host</p> Signup and view all the answers

    Study Notes

    Evolutionary Relatedness and Bacterial Phyla

    • Evolutionary relationships in bacteria are measured by comparing 16S rRNA gene sequences; sequence differences indicate divergence time from a common ancestor.
    • Approximately 30 bacterial phyla are culturable in labs, but estimates suggest over 1,000 possibly undiscovered phyla.
    • Seven major phyla are significant for human health and ecosystems.

    Firmicutes and Actinobacteria

    • Firmicutes, characterized by thick cell walls, include species such as Clostridium that produce dormant, resistant endospores.
    • Endospores withstand extreme conditions: heat, desiccation, radiation, and chemicals.
    • Sporulation occurs under nutrient scarcity, leading to a unique cell division where the polar compartment becomes a forespore.
    • Actinobacteria, including Streptomyces, produce antibiotics and grow as radial filaments; they have a thick waxy coat and high G+C content.

    Proteobacteria

    • A diverse group, including heterotrophs, lithotrophs, and photosynthetic species; all are Gram-negative.
    • Proteobacteria possess an outer membrane loaded with receptor proteins and lipopolysaccharides (LPS), which can be toxic.
    • Enterobacteriaceae, a family within Proteobacteria, contains rod-shaped bacteria like Escherichia coli and Proteus mirabilis, known for their roles in human infections.

    Bacteroidetes

    • Consist of Gram-negative anaerobic rods, crucial for gut health but can also cause abscesses post-surgery, e.g., Bacteroides species.

    Spirochaetes

    • Feature distinctive coiled shapes and periplasmic flagella; include both symbiotic (e.g., in termites) and pathogenic types (e.g., Borrelia burgdorferi, which causes Lyme disease).

    Chlamydiae

    • Obligate intracellular pathogens, grow as inclusion bodies within host cells, causing diseases like pneumonia and sexually transmitted infections.
    • These bacteria alternate between elementary bodies (infectious form) and reticulate bodies (non-infectious, metabolically active).

    Pathogen Evolution Factors

    • Pathogens evolve in three primary environments: zoonotic hosts, sheltered species, and natural environments.
    • Zoonotic hosts can share pathogens with humans, facilitating genetic recombination that allows new infections to emerge.
    • Sheltered species provide environments for bacterial evolution and genetic exchange.
    • Natural environments serve as genetic melting pots where genes related to antibiotic resistance often originate.

    Selected Pathogens

    • Firmicutes examples:
      • Bacillus anthracis causes anthrax.
      • Clostridium difficile leads to intestinal diseases, especially in antibiotic-treated patients.
      • Clostridium botulinum produces botulinum toxin (Botox) and can cause botulism.
      • Clostridium tetani is responsible for tetanus.

    Non-Spore Formers and Their Impact

    • Enterococcus spp. are intestinal microbiota that can cause severe infections, especially in immunocompromised individuals, and are treated with Vancomycin.
    • Lactobacillus and Lactococcus spp. are important in dairy culture, fermenting lactose to produce yogurt and cheese.

    Key Characteristics of Proteobacteria

    • Classified by diverse metabolic pathways and Gram-negative structure.
    • Most bacteria in this phylum can cause infections, with some forming biofilms contributing to increased antibiotic resistance.

    Conclusion

    • Understanding bacterial diversity offers insights into health, ecology, and evolutionary biology.
    • Awareness of how these bacteria evolve and interact with their environments is crucial for managing infections and developing treatments.

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    Description

    This quiz explores the evolutionary relatedness of bacteria through comparisons of 16S rRNA gene sequences and examines major bacterial phyla. Key phyla such as Firmicutes and Actinobacteria are highlighted for their significance in human health and ecosystems. Test your knowledge on bacterial diversity and characteristics!

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