Bacterial Microbiota and Its Impact
50 Questions
0 Views

Choose a study mode

Play Quiz
Study Flashcards
Spaced Repetition
Chat to lesson

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

What is the primary composition of most microbiota?

  • Monospecies biofilms
  • Mixed species (correct)
  • Single genus
  • Purely pathogenic species

    • Which statement about dysbiosis is true?

  • Dysbiosis represents an increase in microbial diversity.
  • It can lead to chronic systemic inflammation. (correct)
  • It solely results from antibiotic use.
  • Dysbiosis has no effect on immune status.

    • What term refers to the balance of microbial communities in the microbiota?

  • Ecological stability (correct)
  • Bacterial pathogenicity
  • Microbial equilibrium
  • Dysbiosis

    • Which of the following can lead to dysbiosis?

    <p>Poor dietary choices (B)</p> Signup and view all the answers

    What is a characteristic of pathogenic bacteria in terms of biofilm formation?

    <p>They only form monospecies biofilms. (A)</p> Signup and view all the answers

    Which type of microbiota is characterized by its persistence in the body?

    <p>Resident microbiota (D)</p> Signup and view all the answers

    What condition is believed to be influenced by GI microbiota?

    <p>Diabetes (D)</p> Signup and view all the answers

    How does excessive hygiene potentially affect the microbiota?

    <p>It may lead to dysbiosis. (C)</p> Signup and view all the answers

    What type of biofilms do pathogenic bacteria commonly form on medical devices?

    <p>Monospecies and sometimes multispecies biofilms (B)</p> Signup and view all the answers

    Which factors do NOT influence the composition of microbiota?

    <p>Genetic predisposition (B)</p> Signup and view all the answers

    How does the size of the plasmid affect its migration through agarose gel?

    <p>Smaller plasmids migrate faster than chromosomes. (A), Larger plasmids migrate slower than chromosomes. (C)</p> Signup and view all the answers

    What is a characteristic of broad host range plasmids?

    <p>They facilitate horizontal gene transfer across various genera and species. (A)</p> Signup and view all the answers

    What role do CRISPR-Cas systems play in bacteria?

    <p>They prevent the acquisition of harmful genes from horizontal gene transfer. (A)</p> Signup and view all the answers

    Why do commensal bacteria generally avoid acquiring extra genetic material?

    <p>They are highly adapted to their niche and avoid the burden of unnecessary genes. (A)</p> Signup and view all the answers

    What typically happens to pathogens in terms of genetic material compared to commensal bacteria?

    <p>Pathogens usually have higher amounts of unnecessary genetic sequences. (D)</p> Signup and view all the answers

    What is the role of a capsule in Streptococcus pneumoniae?

    <p>It protects the bacterium from being killed by the immune system. (D)</p> Signup and view all the answers

    What happens to avirulent S.pneumoniae when injected with killed encapsulated virulent bacteria?

    <p>They acquire the capsule gene and can cause disease. (C)</p> Signup and view all the answers

    Transformation is a genetic mechanism primarily associated with which process?

    <p>Acquisition of genetic information from the environment. (D)</p> Signup and view all the answers

    What characterizes plasmids in relation to the chromosome?

    <p>They replicate independently from the chromosome. (A)</p> Signup and view all the answers

    Which is a consequence of S.pneumoniae lacking a capsule?

    <p>It becomes avirulent and cannot cause disease. (B)</p> Signup and view all the answers

    What initiates the replication process of both chromosomes and plasmids?

    <p>Replication initiation proteins. (C)</p> Signup and view all the answers

    What is the primary function of the DNA polymerase during replication?

    <p>To synthesize new DNA strands. (B)</p> Signup and view all the answers

    Why is S.pneumoniae considered virulent?

    <p>It can evade the immune system due to its capsule. (A)</p> Signup and view all the answers

    Avirulent S.pneumoniae strains are characterized by what genetic feature?

    <p>They do not have the capsule gene. (A)</p> Signup and view all the answers

    What is formed when replication initiation proteins bind to the origin of replication?

    <p>A replication bubble. (B)</p> Signup and view all the answers

    Which condition is mentioned as not largely influenced by microbiota?

    <p>Obesity (A)</p> Signup and view all the answers

    What psychological aspect may be influenced by the GI microbiota?

    <p>Mood disorders (B)</p> Signup and view all the answers

    What nerve connects the brain and the digestive tract?

    <p>Vagus nerve (B)</p> Signup and view all the answers

    What is the primary role of pathogens found in the microbiome?

    <p>Cause harm to host organisms (D)</p> Signup and view all the answers

    Which taxonomic rank is found at the end of the branching hierarchy of bacteria?

    <p>Species (A)</p> Signup and view all the answers

    What assumption does phylogeny typically rely upon?

    <p>Existence of a common ancestor (B)</p> Signup and view all the answers

    How many kingdoms are established based on ribosomal rRNA gene phylogeny?

    <p>Three (C)</p> Signup and view all the answers

    Which of the following is NOT a level of bacterial classification?

    <p>Tribe (B)</p> Signup and view all the answers

    Which of these diseases is associated with the influence of GI microbiota?

    <p>Crohn's disease (D)</p> Signup and view all the answers

    What signifies that there needs to be a mark to go through evolution?

    <p>Phylogeny (C)</p> Signup and view all the answers

    What is transformation in the context of horizontal gene transfer?

    <p>The uptake of DNA from the environment by competent bacteria (D)</p> Signup and view all the answers

    Which statement is correct about the competence of bacteria?

    <p>Competence is a naturally occurring state in some bacteria (C)</p> Signup and view all the answers

    What role does RecA play in homologous recombination?

    <p>It coats single-stranded DNA and facilitates a homology search (B)</p> Signup and view all the answers

    What must be true for ssDNA to be incorporated into a bacterial genome?

    <p>It must have regions of homology to existing chromosomal DNA (B)</p> Signup and view all the answers

    What is the primary challenge to DNA uptake during transformation?

    <p>Degradation of free DNA by DNase (D)</p> Signup and view all the answers

    Which of the following statements describes a pan genome?

    <p>It includes both core genes and distributed genes across a species (A)</p> Signup and view all the answers

    What is the function of ssDNA binding proteins during transformation?

    <p>They protect the ssDNA from restriction enzymes (B)</p> Signup and view all the answers

    What is the main type of DNA that is taken up during the transformation process?

    <p>Single-stranded DNA (A)</p> Signup and view all the answers

    Why are the genes of a supragenome important for bacterial diversity?

    <p>They can introduce unique functions like alternate metabolism and virulence factors (C)</p> Signup and view all the answers

    Which mechanism is NOT a form of horizontal gene transfer?

    <p>Binary fission (C)</p> Signup and view all the answers

    What is the hallmark of transformation in laboratory experiments?

    <p>Inhibition of DNA uptake by DNase (B)</p> Signup and view all the answers

    What is required for RecA to facilitate strand exchange during homologous recombination?

    <p>Regions of homology between the ssDNA and the chromosomal DNA (D)</p> Signup and view all the answers

    What is one key characteristic of competent bacteria?

    <p>They are able to uptake DNA from their environment (B)</p> Signup and view all the answers

    What happens to the ssDNA within the bacterial cell once taken up?

    <p>It is protected by ssDNA binding proteins (B)</p> Signup and view all the answers

    Which is true regarding DNA incorporation into a bacterial genome?

    <p>Restriction enzymes can prevent DNA from being integrated (D)</p> Signup and view all the answers

    Study Notes

    Bacterial Microbiota

    • Bacteria live in multispecies biofilms in the microbiota
    • Pathogenic bacteria often form monospecies biofilms and sometimes multispecies biofilms on indwelling devices (e.g., catheters, joint replacements)
    • Most microbiota is mixed species
    • The microbiota makes up a highly adapted ecology of bacteria
    • Microbiota often contains biofilms
    • Resident microbiota is the own microbiota
    • Transient microbiota comes and goes
    • Dysbiosis represents a microbial imbalance in the microbiota
    • Diet, exercise, antibiotics, and hygiene influence the microbiota
    • Dysbiosis can lead to changes in immune status including inflammation (hyperimmunity) and immunodeficiencies, as well as possibly autoimmune diseases
    • Dysbiosis can lead to chronic systemic inflammation and metabolic disease
    • Hygiene means too much hygiene
    • GI microbiota is being associated with multiple conditions
    • GI microbiota contributes to systemic conditions such as diabetes
    • Obesity is not largely influenced by microbiota
    • Local conditions, such as Crohn's disease and colon cancer, are associated with GI microbiota
    • The Gut-Brain Axis, GI microbiota may influence psychological conditions as well Parkinson's disease
    • The Vagus nerve connects the brain and the gut
    • Pathogens are found in the microbiome meant to murder

    Bacterial Phylogeny

    • To be marked by phylogeny, a mark to go through evolution is needed
    • Phylogeny assumes an ancestor and uses evolution to change gene sequences
    • The bacteria are organized into Kingdom, Phylum, Class, Order, Family, Genus, Species
    • Species are at the end of each branch
    • There are three kingdoms based on ribosomal rRNA gene phylogeny.

    Mechanisms of Horizontal Gene Transfer (HGT)

    • Stress causes bacterial DNA to fragment (e.g., oxidative burst by immune cells)
    • Starvation in deep layers of a biofilm is a stressor
    • Error-prone polymerases do not proofread
    • Transformation is the uptake of DNA from the environment by competent bacteria
    • DNA is free in the environment, making it susceptible to DNase
    • DNase inhibition of DNA uptake during laboratory experiments is a hallmark of transformation
    • Only competent bacteria can take up DNA
    • Competence is a naturally occurring state
    • Competence can be chemically induced in some bacteria
    • Single-strand of DNA (ssDNA) is taken up by the DNA uptake machinery
    • Pili are often associated with DNA uptake machinery
    • RecA protein coats ssDNA, performs homology searches, and replaces it with the chromosome
    • Once inside the cell, DNA is protected by ssDNA binding proteins
    • RecA recombinase binds to the ssDNA and mediates homologous recombination
    • The ssDNA must have regions of homology to DNA already in the chromosome
    • The DNA binds in these stretches and RecA mediates strand exchange
    • If DNA is not cleaved by restriction enzymes (enzymes that cleave DNA), it is incorporated into the genome
    • Numerous additional genes can be introduced into the chromosome as long as they are flanked by regions of homology
    • A bacterial species with a supragenome (pan genome) will have a core genome shared by all the bacteria (comprises 60-70% of the genome)
    • Distributed genes are present in only some of the bacteria in the population, giving rise to different strains
    • Genes encode unique functions — alternate metabolism, virulence factors, etc.
    • Transformation is one genetic mechanism that can give rise to this type of genome structure in a species
    • Transformation of competent cells led to the discovery of DNA
    • Streptococcus pneumoniae is a virulent bacteria that will kill mice
    • S. pneumoniae requires a capsule to keep it from being killed by the immune system
    • Without a capsule S. pneumoniae is avirulent (cannot cause disease)
    • If killed encapsulated virulent bacteria are injected into a mouse along with live avirulent unencapsulated bacteria, the mouse will die. The live bacteria pick up the capsule gene via transformation

    Plasmids

    • Plasmids replicate separately from the chromosome — autonomous replicons
    • Replication initiation proteins bind to the origin of replication to initiate replication
    • Bound replication initiation protein recruits DNA polymerase (which replicates the chromosome) to replicate the plasmid.

    Plasmids and Horizontal Gene Transfer

    • Plasmids can be used to transfer genes between organisms.
    • The size of the plasmid impacts its migration speed in agarose gel electrophoresis.
    • Large plasmids migrate slower than chromosomes
    • Small plasmids migrate faster than chromosomes
    • Broad host range plasmids can transfer genes between different genera and species through horizontal gene transfer.

    CRISPR-Cas System

    • CRISPR-Cas systems are used for gene editing in bacteria.
    • The CRISPR-Cas system protects commensal bacteria from acquiring genes from horizontal gene transfer.
    • Commensal bacteria are highly adapted to their niche environments.
    • Commensal bacteria do not want the added burden of extra genetic material.
    • Pathogenic bacteria often acquire antibiotic resistance genes and virulence factors from mobile genetic elements.

    Studying That Suits You

    Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

    Quiz Team

    Related Documents

    Genetic Exchange Notes 2024 PDF

    Description

    Explore the complexities of bacterial microbiota in this quiz. Learn about the differences between resident and transient microbiota, the significance of biofilms, and how dysbiosis can affect overall health. Understand the influence of diet, hygiene, and other factors on your microbiota.

    More Like This

    Use Quizgecko on...
    Browser
    Open
    Browser
    Browser