Podcast
Questions and Answers
What is a primary disadvantage of sexual reproduction compared to asexual reproduction?
What is a primary disadvantage of sexual reproduction compared to asexual reproduction?
- Slower to produce offspring (correct)
- Generates fewer mutations
- Requires more energy to perform
- Produces identical offspring
Which of the following processes involves the transfer of DNA through a virus?
Which of the following processes involves the transfer of DNA through a virus?
- Transduction (correct)
- Binary fission
- Conjugation
- Transformation
In horizontal transmission of genetic material, which mechanism involves a physical connection between two bacteria?
In horizontal transmission of genetic material, which mechanism involves a physical connection between two bacteria?
- Conjugation (correct)
- Transduction
- Mitosis
- Transformation
What is a limitation of transformation as a method for introducing genetic diversity?
What is a limitation of transformation as a method for introducing genetic diversity?
What characterizes generalized transduction?
What characterizes generalized transduction?
What is the primary role of the conjugation pilus in bacterial gene transfer?
What is the primary role of the conjugation pilus in bacterial gene transfer?
Which statement regarding specialized transduction is correct?
Which statement regarding specialized transduction is correct?
What defines the core genome in bacterial populations?
What defines the core genome in bacterial populations?
What is a characteristic feature of dysbiosis in the human microbiome?
What is a characteristic feature of dysbiosis in the human microbiome?
How do chromosomal islands provide evidence for foreign origin in bacterial genomes?
How do chromosomal islands provide evidence for foreign origin in bacterial genomes?
What role do the epithelial cells in alveoli play in the immune defense of the lungs?
What role do the epithelial cells in alveoli play in the immune defense of the lungs?
Which statement accurately describes the microbial environment of the skin?
Which statement accurately describes the microbial environment of the skin?
How can the gut microbiota stimulate the immune system in healthy individuals?
How can the gut microbiota stimulate the immune system in healthy individuals?
What is a characteristic feature of microbiota in the urogenital tract of women?
What is a characteristic feature of microbiota in the urogenital tract of women?
What happens in the gastrointestinal tract when there is a decrease in stomach acidity?
What happens in the gastrointestinal tract when there is a decrease in stomach acidity?
What primary impact does a high-fiber diet have on the gut microbiome?
What primary impact does a high-fiber diet have on the gut microbiome?
Which of the following factors is least likely to contribute to dysbiosis?
Which of the following factors is least likely to contribute to dysbiosis?
How do short-chain fatty acids (SCFA) affect gut health?
How do short-chain fatty acids (SCFA) affect gut health?
What characterizes the role of Archaea in the gut microbiome?
What characterizes the role of Archaea in the gut microbiome?
What limitation is associated with using mouse models to study human gut microbiota?
What limitation is associated with using mouse models to study human gut microbiota?
Which mechanism allows pathogens to evade phagocytosis by using a protective layer around themselves?
Which mechanism allows pathogens to evade phagocytosis by using a protective layer around themselves?
Which enzyme helps pathogens to break down connective tissue and facilitate further invasion into host tissues?
Which enzyme helps pathogens to break down connective tissue and facilitate further invasion into host tissues?
Which type of secretion system allows bacteria to inject proteins directly into the host cell?
Which type of secretion system allows bacteria to inject proteins directly into the host cell?
What role do adhesins play in the pathogenicity of bacteria?
What role do adhesins play in the pathogenicity of bacteria?
What is a potential drawback of using prebiotics to promote gut health?
What is a potential drawback of using prebiotics to promote gut health?
Which of the following correctly describes the role of exotoxins?
Which of the following correctly describes the role of exotoxins?
In the context of bacterial virulence, what does LD50 signify?
In the context of bacterial virulence, what does LD50 signify?
How does botulinum toxin affect muscle contraction?
How does botulinum toxin affect muscle contraction?
What is the outcome of a pathogen that can remain inside the phagosome without fusing with a lysosome?
What is the outcome of a pathogen that can remain inside the phagosome without fusing with a lysosome?
Which statement correctly defines bacteremia?
Which statement correctly defines bacteremia?
What is the primary mechanism of action for cholera toxin?
What is the primary mechanism of action for cholera toxin?
What effect does diphtheria toxin have on host tissues?
What effect does diphtheria toxin have on host tissues?
Which of the following best describes the term 'cytotoxin'?
Which of the following best describes the term 'cytotoxin'?
Which statement most accurately describes the differences between exotoxins and endotoxins?
Which statement most accurately describes the differences between exotoxins and endotoxins?
What role do peptidoglycan layers play in bacterial cell walls?
What role do peptidoglycan layers play in bacterial cell walls?
How does the structure of gram-negative bacteria differ from that of gram-positive bacteria?
How does the structure of gram-negative bacteria differ from that of gram-positive bacteria?
Which bacterial structure is primarily responsible for maintaining cell morphology during division?
Which bacterial structure is primarily responsible for maintaining cell morphology during division?
What protects the DNA within bacterial endospores from environmental stress?
What protects the DNA within bacterial endospores from environmental stress?
Which protein is involved in the segregation of chromosomes during bacterial cell division?
Which protein is involved in the segregation of chromosomes during bacterial cell division?
The function of the capsule in bacteria primarily relates to which of the following?
The function of the capsule in bacteria primarily relates to which of the following?
What role do alveolar macrophages play in the immune defense of the lungs?
What role do alveolar macrophages play in the immune defense of the lungs?
How do resident bacteria in the vagina help maintain its acidic environment?
How do resident bacteria in the vagina help maintain its acidic environment?
What is a consequence of taking antibiotics for women concerning their vaginal microbiota?
What is a consequence of taking antibiotics for women concerning their vaginal microbiota?
What does an Hfr strain indicate about the genetic makeup of the bacterial cell?
What does an Hfr strain indicate about the genetic makeup of the bacterial cell?
Which characteristic of the gut microbiome plays a role in energy generation for humans?
Which characteristic of the gut microbiome plays a role in energy generation for humans?
What contributes to the sterility of the kidney and bladder?
What contributes to the sterility of the kidney and bladder?
How does specialized transduction differ from generalized transduction in phage-mediated gene transfer?
How does specialized transduction differ from generalized transduction in phage-mediated gene transfer?
What is a key characteristic of chromosomal islands that suggests they originate from foreign DNA?
What is a key characteristic of chromosomal islands that suggests they originate from foreign DNA?
What effect can dysbiosis have on the immune system?
What effect can dysbiosis have on the immune system?
In human microbiome dynamics, what primarily distinguishes a healthy state from a diseased state?
In human microbiome dynamics, what primarily distinguishes a healthy state from a diseased state?
What is a potential long-term impact of dysbiosis on human health?
What is a potential long-term impact of dysbiosis on human health?
Which factor is most likely to promote the development of a healthy gut microbiota?
Which factor is most likely to promote the development of a healthy gut microbiota?
How might the presence of Archaea in the gut microbiome influence obesity?
How might the presence of Archaea in the gut microbiome influence obesity?
What is a critical condition required for inflammation to occur in the gut?
What is a critical condition required for inflammation to occur in the gut?
What distinguishes probiotics from prebiotics in terms of their function?
What distinguishes probiotics from prebiotics in terms of their function?
What is a primary benefit of sexual reproduction compared to asexual reproduction?
What is a primary benefit of sexual reproduction compared to asexual reproduction?
What process describes the uptake of naked DNA from the environment by bacteria?
What process describes the uptake of naked DNA from the environment by bacteria?
In generalized transduction, what determines the genes that can be transferred between bacteria?
In generalized transduction, what determines the genes that can be transferred between bacteria?
What is a significant downside of asexual reproduction in bacteria?
What is a significant downside of asexual reproduction in bacteria?
What term defines the transfer of DNA between species that are not directly related?
What term defines the transfer of DNA between species that are not directly related?
Which of the following mechanisms is NOT typically used by bacteria to colonize host tissues?
Which of the following mechanisms is NOT typically used by bacteria to colonize host tissues?
What is the primary role of hyaluronidase in the context of bacterial infections?
What is the primary role of hyaluronidase in the context of bacterial infections?
Which of the following statements about Type III secretion systems is correct?
Which of the following statements about Type III secretion systems is correct?
Which of the following is a potential consequence of a bacterial capsule?
Which of the following is a potential consequence of a bacterial capsule?
What is one of the limitations of using prebiotics in gut health?
What is one of the limitations of using prebiotics in gut health?
What is the primary consequence of the lipid A component of the LPS molecule in gram-negative bacteria?
What is the primary consequence of the lipid A component of the LPS molecule in gram-negative bacteria?
Which function does the glycocalyx primarily serve for pathogenic bacteria?
Which function does the glycocalyx primarily serve for pathogenic bacteria?
The formation of endospores is a characteristic feature of which type of bacteria?
The formation of endospores is a characteristic feature of which type of bacteria?
How does the structure of the cell wall in gram-negative bacteria differ from that in gram-positive bacteria?
How does the structure of the cell wall in gram-negative bacteria differ from that in gram-positive bacteria?
Which protein is primarily involved in the septation process during bacterial cell division?
Which protein is primarily involved in the septation process during bacterial cell division?
What is the role of dipicolonic acid in bacterial endospores?
What is the role of dipicolonic acid in bacterial endospores?
Which of the following statements regarding exotoxins and endotoxins is correct?
Which of the following statements regarding exotoxins and endotoxins is correct?
What does the term virulence specifically refer to in relation to pathogens?
What does the term virulence specifically refer to in relation to pathogens?
Which of the following best explains the difference between bacteremia and septicemia?
Which of the following best explains the difference between bacteremia and septicemia?
What is the primary action of the Diphtheria toxin produced by C. diphtheriae?
What is the primary action of the Diphtheria toxin produced by C. diphtheriae?
How does the cholera toxin primarily cause diarrhea in infected individuals?
How does the cholera toxin primarily cause diarrhea in infected individuals?
What is the mechanism by which botulinum toxin affects muscle contraction?
What is the mechanism by which botulinum toxin affects muscle contraction?
Which of the following correctly describes the function of exotoxins?
Which of the following correctly describes the function of exotoxins?
What characterizes the action of cytolytic toxins such as hemolysins?
What characterizes the action of cytolytic toxins such as hemolysins?
Which mechanism of horizontal transmission is characterized by the transfer of genetic material through a virus?
Which mechanism of horizontal transmission is characterized by the transfer of genetic material through a virus?
What is a significant drawback of asexual reproduction in bacteria?
What is a significant drawback of asexual reproduction in bacteria?
In the process of transformation, which part of the bacterial cell binds to the double stranded DNA from the environment?
In the process of transformation, which part of the bacterial cell binds to the double stranded DNA from the environment?
Which type of genetic material transfer includes the integration of DNA into the bacterial chromosome as recombinant DNA?
Which type of genetic material transfer includes the integration of DNA into the bacterial chromosome as recombinant DNA?
What is the primary function of the F pilus in bacterial conjugation?
What is the primary function of the F pilus in bacterial conjugation?
Which statement accurately describes specialized transduction?
Which statement accurately describes specialized transduction?
How do chromosomal islands differ from the core genome of bacteria?
How do chromosomal islands differ from the core genome of bacteria?
What is a significant outcome of dysbiosis in the human microbiome?
What is a significant outcome of dysbiosis in the human microbiome?
What characterizes an Hfr strain of bacteria?
What characterizes an Hfr strain of bacteria?
What characteristic of the vaginal microbiota helps maintain its weakly acidic environment?
What characteristic of the vaginal microbiota helps maintain its weakly acidic environment?
Which of the following best describes the impact of the stomach's acidity on microbial colonization?
Which of the following best describes the impact of the stomach's acidity on microbial colonization?
What role do Peyer's patches play in the immune response of the gastrointestinal tract?
What role do Peyer's patches play in the immune response of the gastrointestinal tract?
Which feature of skin microbiota helps to limit the colonization of Staphylococcus aureus?
Which feature of skin microbiota helps to limit the colonization of Staphylococcus aureus?
How does decreased stomach acidity potentially lead to infections in the gastrointestinal tract?
How does decreased stomach acidity potentially lead to infections in the gastrointestinal tract?
How does a high-fiber diet specifically support a diverse gut microbiome?
How does a high-fiber diet specifically support a diverse gut microbiome?
What is the consequence of a high-fat diet on gut health?
What is the consequence of a high-fat diet on gut health?
What factor is critical in determining the severity of inflammation in the gut?
What factor is critical in determining the severity of inflammation in the gut?
Which short-chain fatty acid (SCFA) is primarily associated with promoting a pro-obesity phenotype?
Which short-chain fatty acid (SCFA) is primarily associated with promoting a pro-obesity phenotype?
What is one major limitation of using human-microbiota-associated mouse models?
What is one major limitation of using human-microbiota-associated mouse models?
What is the function of adhesins in bacterial pathogenesis?
What is the function of adhesins in bacterial pathogenesis?
Which of the following statements best describes the role of hyaluronidase in bacterial invasion?
Which of the following statements best describes the role of hyaluronidase in bacterial invasion?
What characteristic of Type III secretion systems distinguishes them from Type II systems?
What characteristic of Type III secretion systems distinguishes them from Type II systems?
Which mechanism allows bacteria to alter their growth conditions and evade the host immune response?
Which mechanism allows bacteria to alter their growth conditions and evade the host immune response?
How do various types of pili contribute to bacterial adherence to host tissues?
How do various types of pili contribute to bacterial adherence to host tissues?
What is the primary role of lipopolysaccharide (LPS) in gram-negative bacteria?
What is the primary role of lipopolysaccharide (LPS) in gram-negative bacteria?
What effect does the presence of thick peptidoglycan layers in gram-positive bacteria have?
What effect does the presence of thick peptidoglycan layers in gram-positive bacteria have?
Which of the following describes the action of the Shiga-like toxin produced by certain E. coli strains?
Which of the following describes the action of the Shiga-like toxin produced by certain E. coli strains?
What characterizes the structure of an endospore in gram-positive bacteria?
What characterizes the structure of an endospore in gram-positive bacteria?
Which bacterial structural component is primarily responsible for maintaining morphology during cell division?
Which bacterial structural component is primarily responsible for maintaining morphology during cell division?
In contrast to exotoxins, what is a critical feature of endotoxins during an immune reaction?
In contrast to exotoxins, what is a critical feature of endotoxins during an immune reaction?
What is the primary function of the glycocalyx in bacterial cells?
What is the primary function of the glycocalyx in bacterial cells?
What is a primary mechanism by which a pathogen evades digestion inside a macrophage?
What is a primary mechanism by which a pathogen evades digestion inside a macrophage?
What distinguishes septicemia from bacteremia?
What distinguishes septicemia from bacteremia?
Which statement best describes the mechanism of cholera toxin?
Which statement best describes the mechanism of cholera toxin?
How does the tetanus toxin affect muscle contraction?
How does the tetanus toxin affect muscle contraction?
What does LD50 measure in terms of pathogenicity?
What does LD50 measure in terms of pathogenicity?
Which of the following statements about exotoxins is true?
Which of the following statements about exotoxins is true?
What virulence factor allows a pathogen to mimic cytokines and alter host immune responses?
What virulence factor allows a pathogen to mimic cytokines and alter host immune responses?
What is the primary effect of diphtheria toxin on host tissues?
What is the primary effect of diphtheria toxin on host tissues?
Which type of bacteria has a thick peptidoglycan layer and appears purple when stained?
Which type of bacteria has a thick peptidoglycan layer and appears purple when stained?
What structural component is present in the outer membrane of gram-negative bacteria that contributes to its characteristics?
What structural component is present in the outer membrane of gram-negative bacteria that contributes to its characteristics?
Which protein is essential for the organization of cell wall extension in bacterial cells?
Which protein is essential for the organization of cell wall extension in bacterial cells?
What is one primary function of the glycocalyx in bacteria?
What is one primary function of the glycocalyx in bacteria?
Which structural feature distinguishes acid-fast bacteria from other types of bacteria?
Which structural feature distinguishes acid-fast bacteria from other types of bacteria?
How do lysozymes affect the bacterial cell wall?
How do lysozymes affect the bacterial cell wall?
What role does FtsZ play in bacterial cell division?
What role does FtsZ play in bacterial cell division?
Which component of endospores provides protection against environmental stresses?
Which component of endospores provides protection against environmental stresses?
How do archaea differ from bacteria in terms of their plasma membrane structure?
How do archaea differ from bacteria in terms of their plasma membrane structure?
What is the primary function of MreB in bacterial cells?
What is the primary function of MreB in bacterial cells?
Which feature distinguishes the endospore production process from typical bacterial division?
Which feature distinguishes the endospore production process from typical bacterial division?
Which structure is involved in the movement of genetic material between bacteria during conjugation?
Which structure is involved in the movement of genetic material between bacteria during conjugation?
What is the primary advantage of endospore formation for bacteria in unfavorable conditions?
What is the primary advantage of endospore formation for bacteria in unfavorable conditions?
What mechanism do archaea use to rotate their archaella?
What mechanism do archaea use to rotate their archaella?
What key feature distinguishes a retrovirus from other viruses?
What key feature distinguishes a retrovirus from other viruses?
Which of the following is a method that bacteria use to defend against viral infections?
Which of the following is a method that bacteria use to defend against viral infections?
What is the primary function of ABC transporters in bacteria?
What is the primary function of ABC transporters in bacteria?
In what way do animal viruses enter host cells compared to bacteriophages?
In what way do animal viruses enter host cells compared to bacteriophages?
Which statement accurately describes the lytic cycle of bacteriophages?
Which statement accurately describes the lytic cycle of bacteriophages?
What characteristic of archaeal DNA distinguishes it from bacterial DNA?
What characteristic of archaeal DNA distinguishes it from bacterial DNA?
Which mechanism is primarily responsible for the adaptation of bacteria to resist viral infection via genetic changes?
Which mechanism is primarily responsible for the adaptation of bacteria to resist viral infection via genetic changes?
What adaptation helps thermophilic bacteria stabilize their proteins at elevated temperatures?
What adaptation helps thermophilic bacteria stabilize their proteins at elevated temperatures?
How do halophiles adapt to high salinity environments?
How do halophiles adapt to high salinity environments?
What is a characteristic feature of microaerophiles?
What is a characteristic feature of microaerophiles?
Which mechanism do bacteria use to communicate cell density in quorum sensing?
Which mechanism do bacteria use to communicate cell density in quorum sensing?
What role do exopolysaccharides play in biofilm formation?
What role do exopolysaccharides play in biofilm formation?
How do obligate anaerobes cope with the toxic effects of oxygen?
How do obligate anaerobes cope with the toxic effects of oxygen?
In the context of biofilms, what is an autolysin's primary function?
In the context of biofilms, what is an autolysin's primary function?
What is a primary benefit of cell-to-cell communication in quorum sensing for bacterial populations?
What is a primary benefit of cell-to-cell communication in quorum sensing for bacterial populations?
What is the primary difference between substrate-level phosphorylation and oxidative phosphorylation?
What is the primary difference between substrate-level phosphorylation and oxidative phosphorylation?
In which of the following conditions would fermentation be utilized over aerobic respiration?
In which of the following conditions would fermentation be utilized over aerobic respiration?
What unfavorable condition is likely to affect microbial growth in cold environments?
What unfavorable condition is likely to affect microbial growth in cold environments?
Which statement accurately describes the proton-motive force?
Which statement accurately describes the proton-motive force?
What phenomenon occurs during the stationary phase of bacterial growth?
What phenomenon occurs during the stationary phase of bacterial growth?
Which category of microbe would require organic carbon sources as a primary nutrient?
Which category of microbe would require organic carbon sources as a primary nutrient?
Which type of respiratory process relies on an alternative acceptor for electrons other than oxygen?
Which type of respiratory process relies on an alternative acceptor for electrons other than oxygen?
What is a common challenge faced when culturing hyperthermophilic organisms?
What is a common challenge faced when culturing hyperthermophilic organisms?
What differentiates sessile growth from planktonic growth in microbial populations?
What differentiates sessile growth from planktonic growth in microbial populations?
Which statement about NAD+ in cellular metabolism is correct?
Which statement about NAD+ in cellular metabolism is correct?
Flashcards
Sexual Reproduction
Sexual Reproduction
Two organisms combine their DNA to create an offspring with mixed genetic material.
Asexual Reproduction
Asexual Reproduction
One organism creates an offspring with identical DNA.
Horizontal Gene Transfer
Horizontal Gene Transfer
Transfer of genetic material between different organisms (not parent to offspring).
Bacterial Transformation
Bacterial Transformation
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Bacterial Transduction
Bacterial Transduction
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Specialized Transduction
Specialized Transduction
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Conjugation
Conjugation
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Hfr (High Frequency of Recombination)
Hfr (High Frequency of Recombination)
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Generalized Transduction
Generalized Transduction
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Chromosomal Islands
Chromosomal Islands
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Mucociliary Escalator
Mucociliary Escalator
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Alveoli Defense
Alveoli Defense
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Urogenital Microhabitat
Urogenital Microhabitat
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Skin Microbiome
Skin Microbiome
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Commensal Gut Bacteria
Commensal Gut Bacteria
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What strengthens a healthy gut microbiota?
What strengthens a healthy gut microbiota?
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What factors can influence dysbiosis?
What factors can influence dysbiosis?
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How does a high-fiber diet benefit the gut?
How does a high-fiber diet benefit the gut?
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How do pathogens cause dysbiosis?
How do pathogens cause dysbiosis?
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Inflammation in the gut: What conditions must be met?
Inflammation in the gut: What conditions must be met?
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What is a virulence factor?
What is a virulence factor?
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Adhesins
Adhesins
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Capsule
Capsule
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Hyaluronidase
Hyaluronidase
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Type III Secretion System
Type III Secretion System
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Bacterial Shapes
Bacterial Shapes
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Glycocalyx Function
Glycocalyx Function
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Cell Wall Comparison
Cell Wall Comparison
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Plasma Membrane Function
Plasma Membrane Function
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Bacterial Cytoskeleton
Bacterial Cytoskeleton
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Nucleoid and Ribosomes
Nucleoid and Ribosomes
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Endospore Function
Endospore Function
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Intracellular Immune Avoidance
Intracellular Immune Avoidance
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Inclusion Bodies
Inclusion Bodies
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Bacteremia vs. Septicemia
Bacteremia vs. Septicemia
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Virulence
Virulence
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ID50 and LD50
ID50 and LD50
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Exotoxin vs. Endotoxin
Exotoxin vs. Endotoxin
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Cytotoxin
Cytotoxin
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Botulinum and Tetanus Toxins
Botulinum and Tetanus Toxins
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Vertical Transmission
Vertical Transmission
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Horizontal Transmission
Horizontal Transmission
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Transformation
Transformation
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Transduction
Transduction
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Alveoli Defense Mechanisms
Alveoli Defense Mechanisms
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Urogenital Microbiome
Urogenital Microbiome
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Conjugation Pilus
Conjugation Pilus
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Hfr Strain
Hfr Strain
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What is dysbiosis?
What is dysbiosis?
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How does a high-fiber diet help gut health?
How does a high-fiber diet help gut health?
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What are the conditions for gut inflammation?
What are the conditions for gut inflammation?
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How do gut bacteria influence obesity?
How do gut bacteria influence obesity?
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What are probiotics and prebiotics?
What are probiotics and prebiotics?
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Main bacterial shapes
Main bacterial shapes
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Gram-positive vs. Gram-negative
Gram-positive vs. Gram-negative
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Bacterial cell membrane function
Bacterial cell membrane function
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What is the nucleoid?
What is the nucleoid?
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ID50 & LD50
ID50 & LD50
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What are adhesion receptors?
What are adhesion receptors?
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What is a capsule?
What is a capsule?
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What is hyaluronidase?
What is hyaluronidase?
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How does the Type III Secretion System work?
How does the Type III Secretion System work?
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What are effector proteins?
What are effector proteins?
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What are the main bacterial shapes?
What are the main bacterial shapes?
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What is the function of the glycocalyx?
What is the function of the glycocalyx?
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How do Gram-positive and Gram-negative bacteria differ?
How do Gram-positive and Gram-negative bacteria differ?
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What is the function of the bacterial plasma membrane?
What is the function of the bacterial plasma membrane?
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What are the key components of the bacterial cytoskeleton?
What are the key components of the bacterial cytoskeleton?
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What are endospores?
What are endospores?
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What is the difference between exotoxins and endotoxins?
What is the difference between exotoxins and endotoxins?
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Pathogen Entry
Pathogen Entry
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Tissue Invasion
Tissue Invasion
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Virulence Factors
Virulence Factors
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Bacterial Cell Wall
Bacterial Cell Wall
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Endospores
Endospores
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Hopanoids
Hopanoids
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Bacterial Cytoskeleton Structure (FtsZ)
Bacterial Cytoskeleton Structure (FtsZ)
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Bacterial Cytoskeleton Structure (MreB)
Bacterial Cytoskeleton Structure (MreB)
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Bacterial Cytoskeleton Structure (Crescentin)
Bacterial Cytoskeleton Structure (Crescentin)
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Bacterial Endospore Function
Bacterial Endospore Function
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What is Sporulation?
What is Sporulation?
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Catabolism
Catabolism
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Anabolism
Anabolism
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Oxidation-Reduction Reactions
Oxidation-Reduction Reactions
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Substrate-Level Phosphorylation
Substrate-Level Phosphorylation
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Oxidative Phosphorylation
Oxidative Phosphorylation
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Proton-Motive Force
Proton-Motive Force
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ATP Synthase
ATP Synthase
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Aerobic Respiration
Aerobic Respiration
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Anaerobic Respiration
Anaerobic Respiration
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Fermentation
Fermentation
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Cytoplasmic Membrane Flexibility
Cytoplasmic Membrane Flexibility
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Heat Shock Response
Heat Shock Response
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Acidophiles
Acidophiles
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Alkaliphilles
Alkaliphilles
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Obligate Aerobe
Obligate Aerobe
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Obligate Anaerobe
Obligate Anaerobe
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Biofilm Formation
Biofilm Formation
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Quorum Sensing
Quorum Sensing
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Archaea vs. Bacteria
Archaea vs. Bacteria
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Reverse Gyrase
Reverse Gyrase
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What distinguishes eukaryotes from prokaryotes?
What distinguishes eukaryotes from prokaryotes?
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Viral Genome
Viral Genome
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Bacteriophage vs. Animal Virus
Bacteriophage vs. Animal Virus
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Lytic vs. Lysogenic Cycle
Lytic vs. Lysogenic Cycle
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Bacteria's Defense Against Viruses
Bacteria's Defense Against Viruses
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Animal Virus Entry Mechanisms
Animal Virus Entry Mechanisms
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Study Notes
Microbial Genetics and Genomics
-
Sexual vs. Asexual Reproduction:
- Both transmit genetic material vertically (parent to offspring).
- Sexual reproduction combines DNA from two parents, generating genetic diversity via chromosomal crossover. This increases the frequency of mutations, potentially advantageous in changing environments. However, it is slower.
- Asexual reproduction creates identical offspring from a single parent, lacking genetic diversity (mutations are random and rare). It is faster.
-
Vertical vs. Horizontal Transmission:
- Vertical transmission is the transfer of genetic material from one generation to the next (e.g., mother cell to daughter cell).
- Horizontal transmission (HT) involves transferring small DNA fragments between closely or distantly related species. This is a mechanism for asexual organisms like bacteria to gain genetic diversity. Examples include transformation, transduction, and conjugation.
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Transformation:
- Uptake of naked DNA from the environment.
- A pilus binds to double-stranded DNA (dsDNA) and pulls it into the periplasm.
- DsDNA becomes single stranded (ssDNA), and the other strand degrades.
- ssDNA integrates into the bacterial chromosome.
- Bacteria have nucleases to degrade dsDNA but are ineffective against ssDNA.
- Not a very efficient method of genetic diversity as environmental DNA is often scarce, and nucleases can degrade ssDNA.
- Can occur when bacteria are dead.
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Transduction:
- Gene transfer via a virus (phage).
- Generalized: Phage DNA transfer is random from one cell to another in infected host cells.
- Specialized: Phage DNA incorporates into the host's chromosome in a specific location.
- The genes transferred are limited by the space in the phage's head.
- Bacteria must be alive to be infected.
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Conjugation:
- Direct cell-to-cell contact via a conjugation pilus (sex pilus) to transfer genes.
- The ability to form a pilus is encoded on a plasmid.
- F+ to F- conjugation:
- Pilus formation and retraction brings cells together.
- One plasmid strand is cut, transferred, and the complementary strand is synthesized in both cells.
- The recipient cell becomes F+.
- Hfr (high frequency of recombination): F plasmid integrates into host chromosome. Genes closest to the integration site are transferred first. May not become F+ but still transfer genetic information. Bacteria must be alive.
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Generalized vs. Specialized Transduction:
- Generalized transduction: Random transfer of bacterial DNA by a virus. The host's DNA can be packaged into viral particles and transferred to another bacterium - Specialized transduction: Specific portions of DNA are transferred. The specific location from where the DNA was integrated from was transferred to the new bacteria.
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Consequences of Genetic Diversity:
- Transduction: V. cholera can acquire genes for cholera toxin via a CTX phage (specialized transduction), transitioning from non-pathogenic to pathogenic.
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Pan and Core Genomes:
- Core genome: Shared genes across all strains of a species.
- Pan genome: Includes core genome plus additional genes unique to certain strains.
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Chromosomal Islands:
- Clusters of genes for specialized functions (e.g., pathogenicity) not essential for survival.
- Often of foreign origin from horizontal gene transfer (HGT) due to differences in nucleotide composition from the core genome and often containing inverted repeats.
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Microbial Diversity Evolution: Mechanisms like horizontal gene transfer and the transfer of functional genes via transduction create microbial diversity.
Microbial Symbiosis with Humans
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Diversity and Dynamics of Microbial Populations:
- Most microbes are harmless and beneficial to the host, with different microhabitats supporting distinct microbial communities.
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Dysbiosis:
- Symbiosis: A healthy gut microbiome involves symbiotic bacteria producing metabolites and antigens, supporting tolerance. - Dysbiosis: Pathogenic bacteria can disrupt healthy microbiota. They secrete antigens and toxins, stimulating immune cells to increase inflammation. This continuous inflammation can lead to pathogenic colonization, intestinal damage, immune disorders, and metabolic dysfunction (immunopathology).
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Oral Cavity and Airways:
- Saliva and immune responses combat microbes in the upper respiratory tract.
- Low microbial presence in the lower respiratory tract, with mucociliary escalator and alveolar defenses.
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Urogenital Tract:
- Kidney/bladder are normally sterile.
- Vaginal acidity and glycogen fermentation by resident bacteria maintain a healthy environment.
- Microbiota composition varies with hormonal changes.
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Skin:
- Microbiota composition varies by environmental conditions (dryness, acidity).
- Mostly gram-positive bacteria reside on the skin.
- Antimicrobial peptides and healthy bacteria help to lower S. aureus colonization.
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Gut Microbiota Roles:
- Fermentation producing SCFA for energy.
- Prevent pathogenic colonization via antimicrobial compounds and nutrient competition.
- Development of immune response (tolerance or inflammation) and stimulation of naïve T cells.
- Supporting Vitamin K, and chemical compound digestion (i.e. medications).
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Gut Microbiota Alterations:
- Microbiome development begins before birth, influenced by factors like birth method (vaginal vs. C-section), feeding (breast milk vs. formula), diet, and age. Microbiota diversity decreases with aging and some dietary choices and other factors.
Gut Microbiota and Disease
- Factors influencing Gut Microbiota: Diet, drugs, age, genetics, pre-existing conditions, microbial diversity, lifestyle (e.g., smoking).
- Mechanisms of Dysbiosis: High-fiber diets support diversity and outcompete pathogens to maintain a healthy microbiota. High-fat diets promote endotoxin absorption and inflammation dysregulating the healthy microbiota.
- Pathogen-Induced Dysbiosis: Disruptions in the balance of commensal and pathogenic bacteria allow pathogens to proliferate.
Host-Pathogen Responses
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Infection Conditions: Exposure, adhesion to surfaces, invasion, growth, spread, and tissue/systemic damage.
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Virulence Factors:
- Adherence: Molecules like adhesins, pili, fimbriae, capsules for attachment to host cells.
- Pili: Used in conjugation and adhesion .
- Invasion: Enzymes (hyaluronidase, coagulase, streptokinase) for breaking down tissue barriers.
- Toxicity: Exotoxins (diphtheria toxin, botulinum toxin, tetanus toxin, cholera toxin) or endotoxins for damaging tissues.
- Immune Evasion: Anti-phagocytic proteins, immune inhibitors, and secretion systems.
- Intracellular Avoidance: Bacteria can survive and multiply inside host cells. This can involve resisting digestion, preventing lysosome fusion, exiting the phagosome etc.
- Adherence: Molecules like adhesins, pili, fimbriae, capsules for attachment to host cells.
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Infection vs. Bacteremia vs. Septicemia:
- Infection: Presence of a microorganism.
- Bacteremia: Bacteria in the bloodstream, often transient and not necessarily harmful.
- Septicemia: Systemic infection in the bloodstream, intense immune response to bacteria.
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Virulence and LD50/ID50:
- Virulence: Severity of disease by a pathogen.
- LD50: Lethal dose (kills 50% of test animals).
- ID50: Infectious dose (infects 50% of test animals)
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Cytotoxins, Endotoxins, Exotoxins, Hemotoxins:
- Cytotoxins: Cell-killing agents
- Exotoxins: Secreted protein toxins (diphtheria, botulinum, cholera).
- Endotoxins: (Lipid component of Gram-negative cell walls).
- Hemotoxins: Affect red blood cells.
- E. coli Toxins:
- Labile toxin causes watery diarrhea.
- Shiga-like toxin causes bloody diarrhea .
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Virulence mechanisms Specific examples of toxins: Toxins like diphtheria, botulinum, tetanus, cholera, cytolytic toxins (hemolysins), and endotoxins cause specific tissue damage by interfering with cellular mechanisms or by triggering immune responses.
Bacteria
- Bacterial Cell Morphologies: Rods (bacilli), spheres (cocci), spirals (spirilla/spirochetes).
- Glycocalyx: Capsule or slime layer, for protection, adherence, and biofilm formation.
- Cell Walls: Different structures between Gram-positive and Gram-negative bacteria. Gram positive contains a thick layer of peptidoglycan and stains purple. Gram negative has a thin layer of peptidoglycan encased in 2 membranes and stains pink. Acid-fast bacteria have a waxy outer layer making them resistant to stains.
- Cytoplasmic Membrane: Permeability barrier, protein anchor, proton motive force generation (energy storage).
- Cytoskeleton: MreB (elongation), FtsZ (division), crescentin (shape).
- Nucleoid and Ribosomes: Nucleoid houses bacterial chromosome (no membrane), ribosomes synthesize proteins.
- Endospores: Dormant forms for survival under harsh conditions .
- Sporulation: Complex process creating an endospore, for bacterial survival .
- Flagella, Fimbriae, Pili: Used for mobility (flagella) and adhesion/gene transfer (fimbriae/pili).
- Bacterial Locomotion: Run (CCW flagellar rotation) and tumble (CW).
- Unique Bacterial Structures: Peptidoglycan cell wall, endospores, single chromosome, flagella, fimbriae, pili.
- Chemotaxis: Bacteria move in response to chemical gradients by changing flagellar rotation.
Archaea
- Archaea as a Separate Domain: Distinctive rRNA sequences, different metabolic pathways, and unique cell wall structures separate archaea from bacteria.
- Archaeal Cell Structures: similar to bacteria in basic shapes and functions, but use different molecules for cell wall and lipids.
- Cell Walls: Composed of pseudomurein or other unique polysaccharides, different from peptidoglycan.
- Plasma Membranes: Ether-linked membrane lipids with isoprene chains (more stable). Can form lipid bilayer or monolayer.
- Cytoskeleton: TubZ, crenactin, ESCRT.
- Unique Archaeal Structures/Pathways: Hami (attachment), archaella (movement with ATP).
Viruses
- Viral Structure: Nucleic acid (DNA or RNA), protein capsid, some have an envelope.
- Bacteriophages, Plant Viruses, Animal Viruses: Differences in host range, entry mechanisms, and replication cycles.
- Lytic and Lysogenic Cycles: Lytic cycle results in phage release, lysogenic cycle results in phage incorporation into host's chromosomes.
- Bacterial Defense Mechanisms: Genetic resistance, restriction enzymes, CRISPR-Cas.
- Animal Virus Entry: Endocytosis, receptor-mediated endocytosis, and membrane fusion.
- Animal Virus Replication: Lytic or lysogenic cycle (DNA or RNA polymerase, transcription of viral mRNA, production of new viral particles, release by budding or cell lysis).
- Retroviruses: Use reverse transcriptase.
- Latent Viruses: Integrate into host's genome, remain inactive until environmental cues trigger replication.
Microbial Metabolism
- Nutrient Transport: Passive/active transport, ABC transporters, siderophores, periplasmic binding proteins for uptake.
- Catabolism vs. Anabolism:
- Catabolism: Breaking down molecules, releasing energy.
- Anabolism: Building up molecules, requiring energy.
- Oxidation-Reduction: Vital for energy transfer in metabolism.
- Substrate-Level vs. Oxidative Phosphorylation:
- Substrate-level: Direct ATP generation.
- Oxidative: ATP generation driven by electron transport chain.
- Fermentation: Partial breakdown without electron transfer to inorganic acceptors (does not require oxygen) – results in lesser ATP byproducts of different organic compounds.
- Aerobic vs. Anaerobic Respiration: Use oxygen or other electron acceptors for energy production.
- ATP, NAD+, etc.: Energy carriers for metabolic processes.
Microbial Growth
- Binary Fission: Bacterial cell division.
- Batch vs. Continuous Culture: Batch culture has a limited nutrient supply. Continuous culture maintains a steady state.
- Growth Phases: Lag, log, stationary, death.
- Sessile vs. Planktonic Growth: Sessile bacteria attach to surfaces, planktonic bacteria remain free in solution.
- Biofilms vs. Cell Mats: Biofilms are surface-attached communities; cell mats are multilayered.
- Temperature Adaptations: Microbes adapt to temperature by altering their membrane fluidity, enzyme structure, or by producing heat-shock proteins.
- pH Adaptations: Microbes adjust their internal pH based on the external environment.
- Oxygen Requirements: Microbes have different oxygen needs including: obligate aerobes, obligate anaerobes, facultative anaerobes, aerotolerant anaerobes, microaerophiles.
- Oxidation and ROS: Oxygen can be toxic to some microbes causing oxidative stress and/or damage.
- Salinity and Osmotic pressure requirements: microbes have specific needs depending on salt and water in their environments
- Bacterial growth: Adapt to different environments including temperature, pH, and oxygen concentrations.
Microbial Regulatory Systems
- Quorum Sensing: Cell-to-cell communication in bacteria based on cell density.
- Autoinducers: Molecules used in quorum sensing.
- Quorum sensing in gram-positive and gram-negative bacteria: The mechanisms of communication difference.
- Quorum Quenching: Methods to interfere with bacteria's ability to communicate.
- Spatial Organization: MreB, FtsZ, Crescentin, and other proteins that play a role in cell division, maintenance of cellular shape, and localization.
- Cell Polarity: Spatial localization of proteins and cellular structures.
- Negative vs Positive Gene Regulation: How regulatory proteins either suppress or promote bacterial gene expression.
- Operons: Groups of genes transcribed together.
- Two-Component Systems: Sensory systems in bacteria.
- Chemotaxis in E. coli: How bacteria respond to chemical gradients using proteins such as Che proteins.
- Stringent Response: Mechanism to cope with environmental changes, slowing growth to preserve resources.
- Global Response Networks and Regulons: Networks that coordinate gene expression in response to stresses.
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Description
This quiz explores key concepts in microbial genetics, focusing on mechanisms of genetic transfer in bacteria as well as the role of the microbiome in human health. It covers topics such as sexual and asexual reproduction, transduction, transformation, and immune defense roles of epithelial cells. Deepen your understanding of how microorganisms interact with their hosts and each other.
