Microbial Genetics and Genomics Quiz
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Questions and Answers

What is a significant disadvantage of sexual reproduction compared to asexual reproduction?

  • It relies on the genetic contribution from two different organisms.
  • It does not allow for chromosomal crossover.
  • It is less advantageous in changing environments.
  • It generates fewer offspring in a shorter time period. (correct)

    • Which of the following best describes horizontal transmission of genetic material?

  • The transfer of DNA between parent and offspring.
  • The vertical transfer of mutations within a species.
  • Genetic material passed exclusively through asexual reproduction.
  • The exchange of DNA between unrelated species. (correct)

    • What is a key factor that limits the effectiveness of transformation in bacteria?

  • The random nature of nucleotide sequences in environmental DNA.
  • The presence of intact double-stranded DNA.
  • The inability to uptake naked DNA from the environment.
  • Nucleases degrading single-stranded DNA within the cytoplasm. (correct)

    • Which statement accurately describes generalized transduction?

    <p>The DNA transferred is limited to what the virus can accommodate.</p> Signup and view all the answers

    Transformation allows for genetic diversity mainly through which process?

    <p>Integration of single-stranded DNA into the bacterial chromosome.</p> Signup and view all the answers

    What is the main role of the pilus during transformation?

    <p>To bind and transport environmental DNA into the bacterial cell.</p> Signup and view all the answers

    What is the primary function of adhesins in bacteria?

    <p>To chemically bind to host cell receptors for attachment</p> Signup and view all the answers

    Which of the following bacteria structures is primarily involved in forming a protective barrier against phagocytosis?

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

    What role do enzymes like hyaluronidase play in bacterial infection?

    <p>They break down tissue barriers to allow for invasion.</p> Signup and view all the answers

    What is a critical difference between specialized transduction and generalized transduction?

    <p>Specialized transduction involves the direct incorporation of viral DNA into the bacterial chromosome, while generalized transduction does not.</p> Signup and view all the answers

    What is one potential negative consequence of consuming prebiotics in relation to gut bacteria?

    <p>They may inadvertently feed pathogenic bacteria.</p> Signup and view all the answers

    Which secretion system is responsible for injecting bacterial proteins directly into host cells?

    <p>Type III secretion system</p> Signup and view all the answers

    Which statement accurately describes the role of the F pilus in bacterial conjugation?

    <p>It facilitates the transfer of one strand of the F plasmid from an F+ cell to an F- cell.</p> Signup and view all the answers

    What is the primary function of chromosomal islands in bacteria?

    <p>They cluster genes responsible for specialized functions such as pathogenicity.</p> Signup and view all the answers

    How does the presence of a capsule affect the visibility of bacteria to phagocytes?

    <p>It hides the Fc antibody, making them less visible.</p> Signup and view all the answers

    What is the role of virulence plasmids in bacterial infections?

    <p>To carry genes that enhance pathogenicity.</p> Signup and view all the answers

    What characterizes dysbiosis in the human microbiome?

    <p>A state where pathogenic bacteria overtake the normal healthy microbiota.</p> Signup and view all the answers

    How does conjugation differ from transduction?

    <p>Conjugation requires a physical connection between cells, whereas transduction does not.</p> Signup and view all the answers

    In the context of host-pathogen interactions, what is the significance of pili structure?

    <p>They facilitate attachment and can assist in motility.</p> Signup and view all the answers

    Which of the following strategies can lead to increased bacterial genetic diversity?

    <p>Conjugation, where genes are transferred from one bacterium to another through a sex pilus.</p> Signup and view all the answers

    What is the significance of the core genome compared to the pan genome in microbial genetics?

    <p>The core genome is the complete set of genes necessary for basic survival.</p> Signup and view all the answers

    What role does the mucociliary escalator play in the respiratory system?

    <p>It filters out harmful microbes from the lungs.</p> Signup and view all the answers

    Which characteristic of the vaginal environment helps to maintain its acidic state?

    <p>Fermentation of glycogen into lactic acid.</p> Signup and view all the answers

    What is a significant way that the skin microbiome differs from the gut microbiome?

    <p>Skin is more populated with gram-positive bacteria due to resistance to environmental conditions.</p> Signup and view all the answers

    How do short-chain fatty acids benefit humans in the gastrointestinal tract?

    <p>They are produced by fermentation of non-digestible carbohydrates.</p> Signup and view all the answers

    What occurs within the Peyer's patches in the gastrointestinal tract?

    <p>They detect bacteria and present them to the immune system for response.</p> Signup and view all the answers

    What is the primary role of a high-fiber diet in maintaining gut microbiota health?

    <p>It promotes diversification of the microbiome.</p> Signup and view all the answers

    What change occurs in the vaginal microbiota after a course of antibiotics?

    <p>Higher levels of commensal yeasts leading to potential infections.</p> Signup and view all the answers

    What is the primary function of goblet cells in the gastrointestinal tract?

    <p>To produce mucus for barrier formation.</p> Signup and view all the answers

    Which condition acts as a crucial factor for inflammation to occur in the gut?

    <p>Deregulation of the innate immune system.</p> Signup and view all the answers

    What effect does a high-fiber diet have on the gut microbiota composition?

    <p>It encourages an increase in beneficial bacteria that aid in digestion.</p> Signup and view all the answers

    How do pathogens potentially cause dysbiosis?

    <p>By disrupting the balance between commensal and pathogenic bacteria.</p> Signup and view all the answers

    What is a significant limitation of using mouse models to study human gut microbiota?

    <p>Human gut microbial taxa may not colonize the mouse gut.</p> Signup and view all the answers

    What happens to microbial colonization in the urogenital tract post-menopause?

    <p>The environment shifts towards a neutral pH.</p> Signup and view all the answers

    What is the role of short-chain fatty acids (SCFA) in relation to obesity?

    <p>They can both mitigate and exacerbate obesity depending on the type.</p> Signup and view all the answers

    What is the impact of a high-fat diet on the gut microbiome?

    <p>It supports the growth of pathogenic bacteria.</p> Signup and view all the answers

    What is one of the mechanisms by which probiotics may fail to restore gut health?

    <p>Most are destroyed by the stomach's acidic pH.</p> Signup and view all the answers

    How does the microbiota primarily contribute to energy metabolism?

    <p>By metabolizing sugars to generate short-chain fatty acids.</p> Signup and view all the answers

    What factor is least likely to influence the development of dysbiosis?

    <p>Increased physical fitness.</p> Signup and view all the answers

    Sexual reproduction generates genetic diversity through chromosomal crossover from each ______.

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

    Asexual reproduction produces offspring with ______ DNA.

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

    Vertical transmission of genetic material occurs from one generation to ______.

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

    Horizontal transmission allows bacteria to achieve genetic diversity through ______ of DNA between species.

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

    Transformation involves the uptake of ______ DNA from the environment by bacteria.

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

    In transduction, genes are transferred between cells via a ______.

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

    Specialized transduction involves the transfer of a specific piece of DNA between infected cells using a ______.

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

    Bacteria must be ______ for conjugation to occur.

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

    The F pilus is also known as the ______ pilus, as it is crucial for fertility during bacterial conjugation.

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

    In Hfr strains, the F plasmid integrates into the bacterial ______, enabling the transfer of chromosomal genes.

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

    Dysbiosis occurs when pathogenic bacteria can overtake the normal healthy ______ by secreting harmful toxins.

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

    Chromosomal islands are believed to be of foreign origin due to their distinct ______ composition compared to the rest of the genome.

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

    The core genome of a species includes the genes that are ______ by all the strains of the same species.

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

    Bacteria in the colon are obligate ______, meaning oxygen would be toxic to them.

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

    Adhesions are typically glycoproteins or lipoproteins found on a bacterial cell wall that can chemically recognize and bind to ______ on the host cell membrane.

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

    The capsule is a polysaccharide coat around the bacteria that prevents them from being recognized by ______.

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

    Type III secretion systems are used to inject bacterial proteins directly into the host cell through ______ contact.

    <p>cell-cell</p> Signup and view all the answers

    The pathogen must be able to adhere to the skin or mucosa to avoid being swept away by the body's natural ______.

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

    Enzymes like hyaluronidase help bacteria invade tissues by breaking down ______ acid, which helps cells attach together.

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

    Biofilms help form permanent adhesion of bacterial populations to ______.

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

    For pathogens to grow and multiply, they must use ______ from cells and produce virulence factors and toxins.

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

    Most microbes get trapped in the mucous of the ciliated mucosal cells lining the ______.

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

    In women, the vagina is weakly ______, which helps maintain a local acidic environment.

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

    The presence of ______ cells in the alveoli helps defend against infection.

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

    Yeasts can become pathogenic in women’s bodies when normal _____ is lost.

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

    The stomach's acidity acts as a normal ______ effect, preventing many bacteria from colonizing.

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

    In cases of malnourishment, decreased stomach acidity allows for bacteria to survive and establish an infection in the less ______ intestine.

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

    Microbiomes begin developing before ______.

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

    Short-chain fatty acids produced by gut bacteria serve as an ______ source for humans.

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

    Antimicrobials produced by other bacteria help keep ______ colonization low on the skin.

    <p>S.aureus</p> Signup and view all the answers

    Vaginally born infants have a microbiome more like their ______ than that of a newborn via c-section.

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

    A high-fiber diet can help to diversify your microbiome and promote bacteria that can help to outcompete ______ bacteria.

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

    A high-fat diet can promote the absorption of ______ across the intestinal barrier, triggering inflammation.

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

    The ratio of ______ and firmicutes may influence the production of short-chain fatty acids.

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

    Probiotics are living microbes that are introduced to restore the natural microbial balance in the ______.

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

    SCFA can stimulate the production of ______ and promote tissue repair in the gut.

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

    The presence of ______ can influence obesity by harvesting energy from ingested foods.

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

    A disruption in the balance of commensal and pathogenic bacteria can lead to ______ and associated diseases.

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

    The severity of disease pathology depends on the host/______ relationship.

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

    Antibiotics can perpetuate dysbiosis by disrupting the balance of healthy and ______ bacteria.

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

    What is the primary function of crescentin in bacterial cells?

    <p>Determines cell shape</p> Signup and view all the answers

    Which structural component of archeal membranes contributes to their stability in extreme environments?

    <p>Isoprene-derived lipids</p> Signup and view all the answers

    During sporulation, what is the first major morphological change that occurs in the bacterial cell?

    <p>Membrane formation around replicated DNA</p> Signup and view all the answers

    Which protein is responsible for bacterial cell division and forms the FtsZ ring?

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

    What unique feature is found in the peptidoglycan structure of bacterial cells?

    <p>Beta 1,3 linkage between NAG and NAT</p> Signup and view all the answers

    Which advantage is associated with the formation of endospores in bacteria?

    <p>Provides resistance to extreme conditions</p> Signup and view all the answers

    What is the role of hami in archaea?

    <p>Assists in surface attachment and biofilm formation</p> Signup and view all the answers

    How do bacteria utilize chemotaxis for locomotion in response to environmental cues?

    <p>By increasing the duration of runs when attracted</p> Signup and view all the answers

    Which mechanism accurately describes the segregation of chromosomes during bacterial cell division?

    <p>ParM pulls chromosomes to opposite poles</p> Signup and view all the answers

    What role does the glycocalyx play in bacteria?

    <p>It allows bacteria to attach to surfaces and evade the immune response.</p> Signup and view all the answers

    What structural difference is found in the cell wall of gram-negative bacteria compared to gram-positive bacteria?

    <p>Gram-negative bacteria possess two cell membranes.</p> Signup and view all the answers

    What is the primary function of the bacterial plasma membrane?

    <p>To act as a permeability barrier and facilitate energy production.</p> Signup and view all the answers

    Which component of gram-negative bacteria can contribute to their virulence?

    <p>Lipopolysaccharide (LPS) on the outer membrane.</p> Signup and view all the answers

    What is the function of penicillin-binding proteins in bacteria?

    <p>To catalyze the formation of cross-links in peptidoglycan.</p> Signup and view all the answers

    Which bacteria morphology is characterized by spiral shape?

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

    What type of linkage is found in the peptidoglycan structure of bacterial cell walls?

    <p>Beta-1,4 linkages between NAG and NAM.</p> Signup and view all the answers

    What is the primary difference between archaeal flagella and eukaryotic flagella?

    <p>Archaeal flagella use ATP for rotation while eukaryotic flagella use a whip-like motion.</p> Signup and view all the answers

    What distinguishes acid-fast bacteria from other types of bacteria?

    <p>A waxy outer coating of mycolic acid.</p> Signup and view all the answers

    What characteristic do archaea and eukaryotes share regarding their DNA?

    <p>Both possess complex DNA with associated histones.</p> Signup and view all the answers

    Which of the following statements about MreB protein is true?

    <p>It helps maintain the shape of rod-shaped bacteria.</p> Signup and view all the answers

    How do bacteriophages primarily inject their viral DNA into host cells?

    <p>By forming small pores in the bacterial membrane.</p> Signup and view all the answers

    How do lysozymes impact bacterial cells?

    <p>By cleaving the glycosidic bonds in the peptidoglycan layer.</p> Signup and view all the answers

    What happens during the lysogenic cycle of bacteriophages?

    <p>Viral DNA integrates into the host genome and replicates with it.</p> Signup and view all the answers

    Which mechanism of defense allows bacteria to memorize and recognize viral DNA?

    <p>Adaptive immunity through CRISPR mechanisms.</p> Signup and view all the answers

    What distinguishes the replication process of retroviruses from that of other viruses?

    <p>They require reverse transcriptase to convert their RNA into DNA.</p> Signup and view all the answers

    Which method is NOT utilized by animal viruses to enter host cells?

    <p>Direct cell lysis upon contact.</p> Signup and view all the answers

    What indicates that environmental stresses are prompting a bacteriophage to switch from lysogenic to lytic cycle?

    <p>Significant threat to host cell survival.</p> Signup and view all the answers

    Which of the following statements is TRUE regarding archaeal tRNA molecules?

    <p>They have archaeosine instead of guanosine.</p> Signup and view all the answers

    What is the main role of FtsZ in bacterial cell morphology?

    <p>Forming a ring structure to aid in septation</p> Signup and view all the answers

    Which component is specifically present in endospores that aids in DNA protection?

    <p>Dipicolonic acid</p> Signup and view all the answers

    How do bacteria primarily move towards chemical attractants?

    <p>By increasing flagellar runs</p> Signup and view all the answers

    What structural feature differentiates archaeal cell walls from bacterial cell walls?

    <p>Use of pseudomurein</p> Signup and view all the answers

    What protein is involved in the localization of cellular components in bacteria during division?

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

    Which mechanism of sporulation involves the engulfing of the forespore by the mother cell?

    <p>Asymmetric division</p> Signup and view all the answers

    What is the primary function of hami in archaeal cells?

    <p>Surface attachment and biofilm formation</p> Signup and view all the answers

    In bacterial movements, what role does the clockwise rotation of flagella play?

    <p>Facilitates tumbling</p> Signup and view all the answers

    What is a significant advantage of bacteria forming endospores?

    <p>Provides protection against environmental threats</p> Signup and view all the answers

    What is a characteristic feature of the archaeal cytoplasmic membrane?

    <p>Can exist as a lipid bilayer or monolayer</p> Signup and view all the answers

    Which statement accurately describes the role of the glycocalyx in bacteria?

    <p>It protects against phagocytosis and assists in pathogenicity.</p> Signup and view all the answers

    What is the primary structural difference between gram-positive and gram-negative bacterial cell walls?

    <p>Gram-positive bacteria have a thick peptidoglycan layer and no outer membrane.</p> Signup and view all the answers

    What role does the S-layer play in bacterial cells?

    <p>It serves as a protective crystalline layer against environmental stress.</p> Signup and view all the answers

    Which characteristic is unique to acid-fast bacteria compared to other types of bacteria?

    <p>Presence of a hydrophobic waxy outer coating of mycolic acid.</p> Signup and view all the answers

    How do penicillin-binding proteins contribute to bacterial cell wall integrity?

    <p>They catalyze the formation of peptide cross bridges between peptidoglycan layers.</p> Signup and view all the answers

    What is a critical function of the bacterial plasma membrane?

    <p>The membrane acts as a permeability barrier and anchors proteins.</p> Signup and view all the answers

    Which of the following statements correctly describes gram-negative bacteria?

    <p>They possess a lipopolysaccharide (LPS) layer on their outer membrane.</p> Signup and view all the answers

    What component is specifically linked to the pathogenicity of bacteria through the capsule?

    <p>The capsule aids in biofilm formation and facilitates adherence.</p> Signup and view all the answers

    Which structural feature of bacterial cells assists in organizing cell wall extension?

    <p>MreB protein organizes the direction of cell wall extension.</p> Signup and view all the answers

    What unique property distinguishes archaeal flagella from bacterial flagella?

    <p>Archaeal flagella rotate unlike the whip-like motion of eukaryotic flagella.</p> Signup and view all the answers

    Which mechanism allows bacterial cells to respond to viral infections by modifying their receptors?

    <p>Genetic resistance</p> Signup and view all the answers

    What is the primary distinction between the lytic and lysogenic cycles in bacteriophages?

    <p>The lytic cycle results in the production of new phages leading to cell lysis.</p> Signup and view all the answers

    Which of the following statements about animal viruses is accurate?

    <p>Animal viruses can enter cells through receptor-mediated endocytosis.</p> Signup and view all the answers

    What mechanism do retroviruses use to integrate into host DNA?

    <p>Using reverse transcriptase to convert RNA into DNA.</p> Signup and view all the answers

    What role does the reverse gyrase play in archaeal thermophiles?

    <p>It introduces positive supercoils to protect DNA.</p> Signup and view all the answers

    In the context of animal viruses, what is the significance of viral tropism?

    <p>The preference of a virus to infect specific host tissues.</p> Signup and view all the answers

    How do restriction endonucleases protect bacteria from viral infections?

    <p>They digest viral nucleic acids upon entry.</p> Signup and view all the answers

    What classifies a virus as enveloped compared to non-enveloped?

    <p>Incorporation of host-derived phospholipid bilayer.</p> Signup and view all the answers

    What is the primary purpose of incorporating viral DNA into the bacterial genome as seen in CRISPR systems?

    <p>To provide an acquired immunity against future infections.</p> Signup and view all the answers

    Study Notes

    Microbial Genetics and Genomics

    • Sexual vs. Asexual Reproduction: Both transmit genetic material vertically.

      • Sexual: Two organisms combine DNA, generating genetic diversity through chromosomal crossover. Slower reproduction.
      • Asexual: One organism produces identical offspring. Faster reproduction, but lower genetic diversity. Mutations are rare and random.

    • Vertical vs. Horizontal Gene Transfer:

      • Vertical: Transfer from one generation to the next (mother cell to daughter cell).
      • Horizontal (Lateral): Transfer of DNA fragments between organisms (even distantly related). Crucial for bacterial diversity in asexual reproduction. Examples include conjugation, transformation, and transduction.

    Transformation

    • Mechanism: Uptake of naked DNA from the environment.
      • Bacteria bind to dsDNA via a pilus.
      • dsDNA is degraded, and ssDNA integrates into the bacterial chromosome.
      • Efficiency is limited by nucleases in the cytoplasm targeting ssDNA; free environmental DNA is scarce.
      • Bacteria can be dead.

    Transduction

    • Mechanism: Horizontal gene transfer via bacteriophages (viruses).
      • Generalized: Random DNA fragment transfer. Phage infects one bacterium, then another, with DNA of original species.
      • Specialized: Specific DNA segment transfer. Phage inserts its DNA into a specific location on the bacterial chromosome.
      • Bacteria must be alive.
      • Clinical Significance Specialized transduction (e.g., cholera toxin gene transfer by a phage).

    Conjugation

    • Mechanism: Direct cell-cell contact for DNA transfer via a conjugation pilus (sex pilus).
      • F+ to F- transfer: F+ cell forms a pilus for contact, then transfers plasmid DNA. Relaxed plasmid is transferred, recipient replicates it. Relaxosome (enzymes) aids in this process. Recipient becomes F+.
      • Hfr strains: F plasmid integrates into the chromosome, transferring chromosomal genes. Variable transfer of genes; not always enough to make F+ - still increases diversity.
      • Bacteria must be alive.

    Generalized vs. Specialized Transduction

    • Generalized: Phage infects a bacterium, DNA is segmented, new phages are released containing some bacterial DNA.
    • Specialized: Phage DNA integrates into the bacterial chromosome. New phages contain both viral and bacterial DNA.

    Bacterial Genetic Diversity (Clinical Significance)

    • These processes contribute to bacterial diversity, allowing bacteria to evolve in response to selective pressures. Some cases of pathogenesis, e.g., cholera toxin transfer via specialized transduction.

    Pan Genome and Core Genome

    • Core genome: Genes present in all strains of a species.
    • Pan genome: Entire collection of genes in all strains of a species (core genome + unique genes)

    Chromosomal Islands

    • Clusters of genes (e.g., pathogenicity genes) not essential for survival.
    • Likely foreign origin due to differences in nucleotide composition and presence of inverted repeats possibly from horizontal gene transfer.

    Microbial Symbiosis with Humans

    Microbial Diversity and Dynamics

    • Most microbes are harmless and benefit the host, with different body sites supporting unique microbial communities.

    Dysbiosis

    • Healthy gut: Symbiotic microbiota produces metabolites (e.g., SCFAs), antigens and collaborates with immune cells for tolerance.
    • Dysbiosis: Pathogens outnumber normal flora by secreting antigens/toxins causing inflammatory response, damage to the intestinal barrier, immune disorders and dysfunction in metabolic pathways.

    Oral Cavity and Airways

    • Antimicrobial saliva; mucociliary escalator sweeps microbes out of lungs. Alveoli are delicate and have robust defenses (surfactants, macrophages, etc.)

    Urogenital Tract

    • Kidney and bladder are sterile.
    • Vagina is acidic due to lactobacilli and glycogen. Microbiome changes with age and fertility. Yeasts can become pathogenic in disturbed conditions. Uncircumcised penis has more anaerobic gut-like microbes.

    Skin

    • Microbiome influenced by dryness, acidity, and oils.
    • Mostly gram-positive due to environmental factors. S. aureus is a concern.

    Gut Microbiota in Pathogenesis

    • Microbiota can protect against pathogens, but some microbes are opportunistic. Changes favor pathogens to outnumber beneficial ones, e.g., use of antibiotics.

    Gut Microbiota Roles

    • Energy source, digestion of complex carbs (fiber); maintaining gut barrier integrity; immune system development; vitamin production; and chemical compound digestion (i.e. medications).

    Gut Microbiome Composition Changes

    • Starts developing before birth (influences from mother and environment). Breastfed vs. bottle-fed; meat diet vs. high-fiber; age and physiology all influence the microbiome composition.

    Gut Microbiota and Disease

    • Factors for dysbiosis: Diet, drugs, sex, age, genetics, BMI, infections, pre-existing disease, microbial diversity, and environment.
    • Pathogen dysbiosis: Pathogens outcompete healthy microbiota for resources, creating a conducive environment for dysbiosis. Antibiotics exacerbate dysbiosis.
    • Inflammation conditions: Stimulation of innate immune cells; disruptions in the gut barrier, increased pathogenic antigens, or immune system dysregulation.

    Gut Microbiota and Energy Metabolism

    • Microbiota metabolizes some sugars to produce SCFAs, potentially contributing to energy harvest and potentially influencing obesity. Methanogens may influence obesity.

    Limitations of Mouse Models

    • Limited microbiota transfer, anatomic differences, and absent human microbiota in models create inaccuracies.

    Gut Microbiota Influence on Obesity

    • Ratio of Bacteroidetes and Firmicutes may affect SCFA production, influencing obesity. Acetate (pro-obesity) vs. butyrate and propionate (anti-obesity).

    Probiotics and Prebiotics

    • Probiotics: Live microorganisms; stomach acidity and host enzymes/bile salts often destroy them.
    • Prebiotics: Indigestible carbohydrates that selectively promote the growth of beneficial gut microbiota.

    Host-Pathogen Responses

    • Infection & Disease Conditions: Exposure to pathogen; adherence to surfaces; tissue invasion; growth; virulence factors; tissue damage.

    Virulence Mechanisms

    • Adhesion: Adhesins, capsules, fimbriae, pili, and flagella.
    • Invasion: Enzymes, cytolytic exotoxins
    • Growth/Toxicity: Virulence plasmids, exotoxins, endotoxins, anti-phagocytic proteins, immune inhibitors, T3SS, effector proteins
    • Immune avoidance: Intracellular survival within macrophages, mimicking host cytokines, avoiding antigen presentation, inhibiting programmed cell death.

    Infection Terms

    • Infection: Presence and growth of a microorganism inside a host.
    • Bacteremia: Bacteria detected in the bloodstream (localized, often cleared).
    • Septicemia: A blood-borne systemic infection triggering a severe immune response (septic shock, death).

    Virulence

    • Severity of disease caused by a pathogen. Virulence factors aid in the infection process.

    LD50 and ID50

    • ID50: Infectious dose needed to cause infection in 50% of inoculated individuals.
    • LD50: Lethal dose to kill 50% of inoculated individuals.

    Toxin Types

    • Cytotoxin: Kills host cells.
    • Exotoxin: Proteins secreted, mainly by Gram-positive bacteria (high toxicity, denatured by heat).
    • Endotoxin: Components on the surface of Gram-negative bacteria (LPS), induces immune responses.
    • Hemotoxin: Damages red blood cells.

    Specific Toxin Mechanisms

    • Diphtheria toxin: Blocks protein synthesis; respiratory tissue damage.
    • Botulinum/Tetanus toxins: Neurotoxins disrupting acetylcholine release/signaling (opposite effects – botulinum prevents, tetanus prolongs, muscle contraction).
    • Cholera toxin: Increased cAMP levels, diarrhea.
    • Cytolytic toxins (hemolysins, staph alpha-toxin): Pore-forming proteins disrupting cell membranes.
    • Endotoxins: Immune response, septic shock.

    Additional notes on factors to consider (can add these if needed):

    • Bacterial strains have varied virulence profiles due to differences in virulence factors they possess.
    • Infection severity also depends on host factors (e.g., immune response, pre-existing conditions).

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    Description

    Test your knowledge on microbial genetics, focusing on sexual and asexual reproduction as well as gene transfer mechanisms. This quiz covers essential concepts such as vertical and horizontal gene transfer, and the process of transformation in bacteria. Challenge yourself and deepen your understanding of these foundational topics in microbial genetics.

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