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Questions and Answers
What is the definition of pathogenicity?
What is the definition of pathogenicity?
- The actual damage or injury that impairs host function
- The enhanced ability of microbes to attach to host tissues
- The ability of a parasite to inflict damage on the host (correct)
- The ability of a microorganism to establish in a host
How do pathogens typically adhere to epithelial cells?
How do pathogens typically adhere to epithelial cells?
- By gaining access to host tissues through a portal of entry
- Via receptors on the pathogen's surface that enable it to bind to host cells
- Through interactions between molecules on the pathogen and host tissues (correct)
- By forming biofilm and adhering to the host via the biofilm
What are adhesins on a pathogen's surface primarily composed of?
What are adhesins on a pathogen's surface primarily composed of?
- Carbohydrates
- Nucleic acids
- Peptidoglycan
- Glycoprotein or lipoprotein (correct)
What is the critical factor in establishing an infection for pathogens?
What is the critical factor in establishing an infection for pathogens?
What are host receptors that pathogens bind to primarily composed of?
What are host receptors that pathogens bind to primarily composed of?
Which of the following is a function of the complement system?
Which of the following is a function of the complement system?
What is the role of toll-like receptors in phagocytes?
What is the role of toll-like receptors in phagocytes?
What is a key transcription factor activated in many different pathways in phagocytes?
What is a key transcription factor activated in many different pathways in phagocytes?
What is the main role of leukocytes at the site of infection during inflammation?
What is the main role of leukocytes at the site of infection during inflammation?
What can lead to septic shock in the body?
What can lead to septic shock in the body?
What is the main function of Granzyme?
What is the main function of Granzyme?
What is the role of Interferons in the immune response?
What is the role of Interferons in the immune response?
What is the function of T lymphocytes (T cells) in the immune response?
What is the function of T lymphocytes (T cells) in the immune response?
What is the characteristic of B lymphocytes in terms of specificity?
What is the characteristic of B lymphocytes in terms of specificity?
What is the main characteristic of adaptive immunity?
What is the main characteristic of adaptive immunity?
What is the function of bacterial capsules in pathogenicity?
What is the function of bacterial capsules in pathogenicity?
What is the role of adherence structures such as fimbriae, pili, and flagella in bacterial infections?
What is the role of adherence structures such as fimbriae, pili, and flagella in bacterial infections?
What is the process of colonization in the context of host-pathogen interactions?
What is the process of colonization in the context of host-pathogen interactions?
What is the significance of virulence attenuation in pathogen strains?
What is the significance of virulence attenuation in pathogen strains?
When do opportunistic infections occur?
When do opportunistic infections occur?
Which cells primarily drive innate immunity?
Which cells primarily drive innate immunity?
What is the process of differentiation of blood stem cells into different blood cells influenced by cytokines and chemokines called?
What is the process of differentiation of blood stem cells into different blood cells influenced by cytokines and chemokines called?
Which type of stem cells produce T cells, B cells, and natural killer cells?
Which type of stem cells produce T cells, B cells, and natural killer cells?
What is the main function of lymph nodes?
What is the main function of lymph nodes?
What is the primary driving force behind competitive exclusion by harmless microbes?
What is the primary driving force behind competitive exclusion by harmless microbes?
Which of the following is true about coagulase and streptokinase?
Which of the following is true about coagulase and streptokinase?
What is the mechanism of action of Diphtheria exotoxin?
What is the mechanism of action of Diphtheria exotoxin?
What is the function of Botulinum toxin?
What is the function of Botulinum toxin?
What is the role of endotoxins in bacterial pathogenesis?
What is the role of endotoxins in bacterial pathogenesis?
What is the difference between innate immunity and adaptive immunity?
What is the difference between innate immunity and adaptive immunity?
What is the function of a virion in the context of viruses?
What is the function of a virion in the context of viruses?
What is the primary role of capsid in a virus?
What is the primary role of capsid in a virus?
What is the characteristic of enveloped viruses?
What is the characteristic of enveloped viruses?
What is the outcome of a lysogenic infection?
What is the outcome of a lysogenic infection?
How can viruses be classified based on their genetic material?
How can viruses be classified based on their genetic material?
What is the main function of virion surface proteins in a virus?
What is the main function of virion surface proteins in a virus?
What is the primary driving force behind the maintenance of small microbial genomes?
What is the primary driving force behind the maintenance of small microbial genomes?
What evolutionary mechanism plays a significant role in microbial evolution by allowing DNA transfer between distant evolutionary branches?
What evolutionary mechanism plays a significant role in microbial evolution by allowing DNA transfer between distant evolutionary branches?
Which genetic event is more frequent in microbial genome dynamics, contributing to the maintenance of small microbial genomes?
Which genetic event is more frequent in microbial genome dynamics, contributing to the maintenance of small microbial genomes?
What is the result of a gain-of-function mutation in E. coli after 31,500 generations?
What is the result of a gain-of-function mutation in E. coli after 31,500 generations?
What role do gene families, including homologs, orthologs, and paralogs, play in genome evolution and diversification?
What role do gene families, including homologs, orthologs, and paralogs, play in genome evolution and diversification?
What allows one gene copy to evolve new functions while the other maintains the original function?
What allows one gene copy to evolve new functions while the other maintains the original function?
What is the primary driving force behind competitive exclusion by harmless microbes?
What is the primary driving force behind competitive exclusion by harmless microbes?
What is the characteristic of B lymphocytes in terms of specificity?
What is the characteristic of B lymphocytes in terms of specificity?
What is the role of endotoxins in bacterial pathogenesis?
What is the role of endotoxins in bacterial pathogenesis?
What is the main function of Granzyme?
What is the main function of Granzyme?
What is the main role of leukocytes at the site of infection during inflammation?
What is the main role of leukocytes at the site of infection during inflammation?
What are host receptors that pathogens bind to primarily composed of?
What are host receptors that pathogens bind to primarily composed of?
What is a characteristic of the influenza A virus genome?
What is a characteristic of the influenza A virus genome?
What is the causative agent of COVID-19?
What is the causative agent of COVID-19?
What is a characteristic of lysogeny maintenance in phages?
What is a characteristic of lysogeny maintenance in phages?
What is a feature of retrovirus integration into the host genome?
What is a feature of retrovirus integration into the host genome?
What is the primary source of genetic diversity in viruses?
What is the primary source of genetic diversity in viruses?
What is the role of viroplasms in some eukaryotic cells during viral infection?
What is the role of viroplasms in some eukaryotic cells during viral infection?
What can be inferred from >97% SSU rRNA sequence identity?
What can be inferred from >97% SSU rRNA sequence identity?
What is the primary purpose of stable isotope probing in microbial communities?
What is the primary purpose of stable isotope probing in microbial communities?
What does metaproteomics measure in a microbial community?
What does metaproteomics measure in a microbial community?
What is the advantage of using multilocus sequence analysis over SSU ribosomal RNA genes for distinguishing species?
What is the advantage of using multilocus sequence analysis over SSU ribosomal RNA genes for distinguishing species?
What is the main role of stable isotopes and isotopic fractionation in microbial ecosystems?
What is the main role of stable isotopes and isotopic fractionation in microbial ecosystems?
What is the significance of microbial diversity in ecosystems?
What is the significance of microbial diversity in ecosystems?
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Study Notes
Exotoxins and Innate Immunity in Bacterial Pathogenesis
- About 2 million people in the United States are affected by various medical procedures such as surgery, biopsy, catheterization, and hypodermic injection, with a mortality rate of approximately 5%.
- Pathogenic bacteria release enzymes that break down the host's tissues, such as hyaluronidase from Streptococcus pyogenes and collagenase from Clostridia causing gangrene.
- Coagulase and streptokinase are virulence factors that manipulate blood clotting, affecting the immune system's ability to combat infections.
- Exotoxins, including AB toxins, cytolytic toxins, and enterotoxins, cause disease by inhibiting host cell function or killing host cells.
- Diphtheria exotoxin, produced by Corynebacterium diphtheriae, blocks protein synthesis by ADP-ribosylation of the elongation factor EF-2.
- Botulinum toxin, produced by Clostridium botulinum, inhibits muscle contraction by cleaving proteins involved in releasing acetylcholine.
- Tetanus toxin, produced by Clostridium tetanus, floods neuromuscular junctions with acetylcholine, causing muscle contraction.
- Cholera enterotoxin, produced by Vibrio cholera, causes massive fluid secretion into the intestinal lumen by affecting cellular processes and ionic balance.
- Cytolytic exotoxins degrade the cytoplasmic membrane, causing cell lysis and death, often through phospholipase activity or pore formation.
- Endotoxins, part of the lipopolysaccharide component of Gram-negative bacterial outer membranes, are released when bacterial cells lyse and are generally less toxic than exotoxins.
- Innate immunity is the nonspecific immunity of multicellular organisms that targets pathogens seeking to colonize the host and involves rapid responses by phagocytes.
- Adaptive immunity is the acquired ability to recognize and destroy specific pathogens or their products, involving a response by lymphocytes and post-exposure immunity.
Microbial Ecosystems and Diversity: Key Concepts and Analytical Approaches
- Nucleotide sequence differences between homologous genes reflect accumulated mutations since a common ancestor, and can be used to infer relationships
- SSU ribosomal RNA genes are highly conserved and easily sequenced for inferring relationships; >97% SSU rRNA sequence identity indicates the same species
- Multilocus sequence analysis using protein-encoding genes can distinguish species that cannot be resolved by rRNA sequences
- Whole genome analysis is increasingly common, allowing reconstruction of metabolic/physiological characteristics and estimation of relatedness using average nucleotide identity
- Metaproteomics measures protein diversity and abundance in a microbial community, while metabolomics analyzes cellular and extracellular metabolites
- Direct chemical measurements and microsensors are used to measure specific metabolites and activities in microbial habitats
- Stable isotopes and isotopic fractionation can trace the biological or geological origin of ancient environments
- Stable isotope probing involves feeding microorganisms with labeled substrates to identify those utilizing specific compounds in a microbial community
- Microbes account for ~50% of all biomasses on Earth, residing in various habitats within ecosystems
- Microbial diversity is expressed through species richness (total number of species) and abundance (proportion of each species) in an ecosystem
- Guilds, consisting of metabolically related microbial populations, form communities that interact with macroorganisms and abiotic factors
- Microbes play essential roles in biogeochemical cycles, including the transformations of key elements such as C, N, S, and Fe, through oxidation-reduction reactions
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