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Questions and Answers
What is the primary function of heterocysts in Anabaena?
What is the primary function of heterocysts in Anabaena?
Which structural feature of heterocysts helps to protect them from oxygen?
Which structural feature of heterocysts helps to protect them from oxygen?
What type of cells are intercalated with heterocysts in Anabaena chains?
What type of cells are intercalated with heterocysts in Anabaena chains?
What metabolic characteristic is notably increased in heterocysts?
What metabolic characteristic is notably increased in heterocysts?
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What occurs to photosystem II in heterocysts to facilitate their function?
What occurs to photosystem II in heterocysts to facilitate their function?
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What is the significance of dipicolinic acid (DPA) during spore germination?
What is the significance of dipicolinic acid (DPA) during spore germination?
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Which of the following components is responsible for the lethal toxin of anthrax?
Which of the following components is responsible for the lethal toxin of anthrax?
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What initiates the process of spore germination after dormancy?
What initiates the process of spore germination after dormancy?
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Which plasmid contains genes for toxin production in anthrax?
Which plasmid contains genes for toxin production in anthrax?
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What is the main role of the capsule in vegetative cells of anthrax?
What is the main role of the capsule in vegetative cells of anthrax?
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Which system in Pseudomonas aeruginosa uses AHL autoinducers?
Which system in Pseudomonas aeruginosa uses AHL autoinducers?
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Which of the following statements describes Myxobacteria fruiting body formation?
Which of the following statements describes Myxobacteria fruiting body formation?
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What characteristic distinguishes Myxospores from endospores?
What characteristic distinguishes Myxospores from endospores?
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What type of developmental cycle does Bacillus endospore formation represent?
What type of developmental cycle does Bacillus endospore formation represent?
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What is the purpose of estimating transcription factor (TF) activities in network inference?
What is the purpose of estimating transcription factor (TF) activities in network inference?
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Which nutritional factor is associated with the GerA receptor in Bacillus subtilis germination?
Which nutritional factor is associated with the GerA receptor in Bacillus subtilis germination?
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In the context of Bacillus subtilis, what is the consequence of spore germination on optical density?
In the context of Bacillus subtilis, what is the consequence of spore germination on optical density?
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What do germination receptors in Bacillus subtilis function as?
What do germination receptors in Bacillus subtilis function as?
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During which phase does the outgrowth of a spore in Bacillus subtilis occur?
During which phase does the outgrowth of a spore in Bacillus subtilis occur?
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According to the network inference process, which option correctly matches one of the activities related to TFs?
According to the network inference process, which option correctly matches one of the activities related to TFs?
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What is the primary function of nitrogenase in cyanobacteria?
What is the primary function of nitrogenase in cyanobacteria?
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Which of the following statements about cyanobacteria is accurate?
Which of the following statements about cyanobacteria is accurate?
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How does O2 interfere with nitrogen fixation in cyanobacteria?
How does O2 interfere with nitrogen fixation in cyanobacteria?
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Which cyanobacteria can utilize atmospheric N2 as a nitrogen source?
Which cyanobacteria can utilize atmospheric N2 as a nitrogen source?
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What characterizes the process of sporulation in Streptomycetes?
What characterizes the process of sporulation in Streptomycetes?
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What is the significance of the GS/GOGAT pathway in nitrogen assimilation?
What is the significance of the GS/GOGAT pathway in nitrogen assimilation?
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Which of the following is a characteristic feature of filamentous cyanobacteria?
Which of the following is a characteristic feature of filamentous cyanobacteria?
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What does the GC content in cyanobacterial genomes indicate?
What does the GC content in cyanobacterial genomes indicate?
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What characteristic makes Mycobacterium tuberculosis difficult to stain?
What characteristic makes Mycobacterium tuberculosis difficult to stain?
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How do mycobacteria primarily divide?
How do mycobacteria primarily divide?
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What did Rudolf Virchow discover about the effects of tuberculin?
What did Rudolf Virchow discover about the effects of tuberculin?
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What does the term 'acid fast' refer to in the context of Mycobacterium tuberculosis?
What does the term 'acid fast' refer to in the context of Mycobacterium tuberculosis?
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What role does the mycomembrane play in mycobacterial cells?
What role does the mycomembrane play in mycobacterial cells?
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What is the significance of mycolic acids in mycobacterial cells?
What is the significance of mycolic acids in mycobacterial cells?
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Study Notes
Endospore Formation
- Endospores are dormant bacterial cells
- Highly resistant to harsh conditions like heat, desiccation, chemicals (bleach, chloroform), enzymes (lysozyme), and antibiotics. UV radiation.
- A spore is a dormant cell.
- Protective layers: Cortex (multi-layered coat of ~80 proteins)
- First publication on endospore formation (1876)
- Types of spore-forming bacteria: Bacillus, Listeria, Staphylococcus, and Clostridium.
- Specific diseases caused by spore-forming bacteria/examples: Anthrax (Bacillus anthracis), food poisoning (Bacillus cereus, Listeria monocytogenes), colitis and diarrhea (Clostridium difficile), botulism (Clostridium botulinum), tetanus (Clostridium tetani)
Sporulation Cycle
- Sporulation is the process of forming an endospore.
- Germination is the process of the endospore returning to a vegetative cell.
- Spores are formed in response to nutrient limitation.
- Spores germinate when favorable conditions are encountered.
- The spore serves as a delivery vehicle.
- The vegetative cell causes the disease.
Spo0A
- Spo0A is the master regulator of sporulation.
- It's a response regulator.
- It has a regulatory domain (Asp phosphorylation site) and an effector domain (DNA binding).
- Spo0A is activated by a phosphorelay.
Regulation of the phosphorelay (of Spo0A)
- The phosphorelay is regulated by redox state, DNA damage, and cell density (quorum sensing).
- Key proteins involved include KinA, KinB, KinC, Spo0F, Spo0B and Spo0E (phosphatase).
Asymmetric Division
- Asymmetric division is the process by which a cell divides unevenly, producing a different fate for each daughter cell.
- Spores are formed via asymmetric cell division.
Sigma Factors in B. subtilis
- B. subtilis has 18 sigma factors.
- 1 primary sigma factor and 17 other alternative factors.
- These factors are involved in different stages or cell processes.
- Examples of primary factors: general stress response, motility, chemotaxis, autolysis, spore formation (early), spore formation (late), stationary phase and a few examples of some alternative factors: antimicrobial resistance and cell envelope stress.
Compartmentalization of Gene Expression
- Gene expression is compartmentalized in spore-forming bacteria.
- Different sigma factors control gene expression in different regions of the cell.
σF Inhibition/Activation
- σF inhibition involves the anti-σ factor SpoIIAB or AB.
- σF activation is triggered by dephosphorylation of SpollAA by SpollE.
- σF is active after dephosphorylation of the anti-σ factor.
- σF is synthesized as pro-σF and then activated by proteolysis.
Biofilms
- Biofilms are matrix-encased microbial communities.
- They are found at interfaces of solid-air, solid-liquid and air-liquid surfaces.
- Biofilms can contain more than one microbial species.
- Biofilms formation shows some benefits like protection, colonization and communal behavior.
- Steps in biofilm formation: adhesion, colonization, growth and matrix formation and sometimes detachment.
Anthrax
- Bacillus anthracis is a Gram-positive, rod-shaped bacterium.
- It's a Category A bioterror agent that causes anthrax.
- Spores are the delivery vehicle (cause disease).
- Vegetative cells cause disease symptoms.
- Toxins (PA, LF, EF) are important virulence factors produced by vegetative cells.
C. difficile
- C. difficile is a Gram-positive, anaerobic, spore-forming rod-shaped bacterium.
- Pathogenic C. difficile produces toxins (TcdA and TcdB) that contribute to the symptoms of pseudomembranous colitis.
- C. difficile is a nosocomial agent that causes colitis and diarrhea.
- Antibiotic treatment can trigger the proliferation of C. difficile.
- C. difficile infections are commonly linked to hospitals and clinics.
Myxobacteria
- Myxobacteria can form fruiting bodies, which are specialized structures during unfavorable conditions.
- Myxobacteria fruiting bodies contain dormant spores, which are more resistant than vegetative cells.
- Important for predation.
- Other factors: Mounded aggregates, Lysis of prey, Swarm.
- Myxobacteria show diverse spore-bearing structures.
Bdellovibrio
- Bdellovibrio bacteriovorus is a Gram-negative, parasitic bacterium.
- It feeds on other bacteria (predation).
- The cycle involves attachment, penetration of the prey's wall, reproduction within the prey, release of progenies and eventually prey lysis.
Antibiotics
- Chemical agents that kill or inhibit the growth of microbes.
- Natural products or synthetic drugs.
- Common uses: combating bacterial infections.
- Common targets of antibiotics: Cell wall synthesis, DNA synthesis, Protein synthesis, RNA synthesis, Folic acid metabolism.
- Important applications: Treating infectious diseases, controlling bacteria and some fungi.
- Types of action: Bacteriostatic, Bacteriocidal, Fungicidal, Viricidal.
Antimicrobial resistance
- Resistance to antibiotics arises through genetic mechanisms such as: Target site modifications, Inactivation of antibiotics by hydrolysis, Reduction in membrane permeability, and Alternative metabolic pathways.
- Pathogens can acquire resistance mechanisms through vertical or horizontal evolution. Vertical evolution is through inherited mutations while horizontal evolution is via plasmids, transduction, transformation etc.
- Resistance mechanisms include modifications in the antibiotic target, changes in the target site, reduced permeability and increased efflux and alternative pathways.
Bacterial Phylogeny
- A hierarchical classification highlighting the evolutionary relationships between taxa or groups of similar organisms.
Cyanobacteria
- Photosynthetic bacteria that fix carbon and produce oxygen.
- An important factor: nitrogen fixation (conversion of N₂ to NH⁴⁺) is inhibited by O₂.
Nitrogen Fixation
- The process that converts atmospheric nitrogen into ammonia using nitrogenase.
- Important for the production of organic nitrogen in cells.
Mycobacteria
- Gram-positive bacteria, with high GC content.
- Mycobacterium tuberculosis is a pathogen that causes tuberculosis.
- Mycobacterium leprae causes leprosy.
- Their thick cell walls and mycolic acids make them very resistant to various agents.
Specific Details about Microorganisms
- Include details about bacterial shapes, sizes and traits (whether they are Gram-positive or Gram-negative etc.).
Specific Infections
- Include details about particular diseases/symptoms and causes of illness (e.g. tetanus, botulism, anthrax, TB, Lyme disease, etc..).
Important scientists and their discoveries
- Provide information about their impact on scientific breakthroughs or on treatment approaches for infectious diseases.
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Description
Test your knowledge on the functions and characteristics of heterocysts in Anabaena, the mechanics of spore germination, and the biology of anthrax. This quiz covers essential microbial processes and the unique features of different bacterial cells. Challenge yourself with questions on metabolic adaptations and toxin production.