Microbio 4000: osu Ch 18 Final Test
Questions All Solved.
What are the five required steps for a pathogen to cause disease in its host (pathogenesis) -
Answer 1. Entry into host, vulnerable to immune system
2. Attachment and colonization
3. Avoidance of host immunity
4. Host damage
5. Exit from host, and infect others
Virulence factors - Answer These are traits that enhance a pathogen's ability to cause disease
• Pili (attachment, movement, sex)
• Enzymes that harm the host or prevent detection (trick or distract host)
• Proteins that disrupt normal cellular function (ex. replicate in the phagosome)
• Capsule
• Enzymes that inactivate antibiotics (beat out competitors)
Major mechanism that bacteria use to acquire new virulence factors - Answer Horizontal
gene transfer, they can even transform non-pathogens into pathogens!
Horizontal gene transfer: transformation, conjugation, transduction and transposition - Answer
• Transformation - naked/dead DNA picked up by cell
• Conjugation - sex pili used
• Transduction - bacteriophage
• Transposition - "jumping genes" copy + pasting from genomes
Genomic island - Answer When a whole block of DNA is transferred by HGT from one
organism to another, and is integrated into the host chromosome
Pathogenicity island - Answer If the genomic island increases the fitness of a microbe in its
host (virulence factors)
Identification of a pathogenicity island - Answer Pathogenicity islands look different
compared to the rest of the genome (such as having a lower GC content)
Typically flagged by phage or plasmid genes
, Adhesins - Answer Any microbial virulence factor that are required for attachment
Why is attachment required for all microbes that colonize in a host? - Answer To avoid being
removed from the organism
Which monomers make up pili adhesion molecules - Answer Pilin protein
Which region of pili is assembled first, what does it have on it? - Answer The tip of the pili is
assembled first at the cell surface it contains the adhesin protein that binds to host receptors
Which region of a pili interacts with host receptors? - Answer The tip, as it contains the
adhesin protein that binds to host receptors
Type I pili - Answer Static, hairlike appendages used only for
attachment (think: velcro, adhesion only)
Type IV pili - Answer Dynamic, thin, and flexible for "twitching
motility", also energetically expensive (think: fishing rods, adhesion and motility)
Are all adhesions pili? - Answer Nope! Different adhesins enable attachment to different
tissues, and determine the host species and cell types these bacteria will attach and colonize!
Know that most bacteria colonizing the body will do so as.... - Answer Biofilms
Surfaces which biofilms can form on in the body - Answer Organic (ex. lungs, bladder, skin,
stomach lining) or inorganic (ex. catheters and surgical implants)
What is quorum sensing? - Answer Cell-to-cell communication which enables biofilms to
coordinate behavior, positive feedback loops
Why do biofilm-forming infections lead to chronic infections, which will also lead to chronic
inflammation? - Answer The presence of biofilms chronically activates Toll-Like receptors and
triggers inflammation, biofilms also generally resist host defenses and antimicrobial compounds
Order of bacterial pathogenesis (extracellular bacteria) - Answer 1) entry into the body
2) adhesion to host cell surface or tissue
3) colonization
Questions All Solved.
What are the five required steps for a pathogen to cause disease in its host (pathogenesis) -
Answer 1. Entry into host, vulnerable to immune system
2. Attachment and colonization
3. Avoidance of host immunity
4. Host damage
5. Exit from host, and infect others
Virulence factors - Answer These are traits that enhance a pathogen's ability to cause disease
• Pili (attachment, movement, sex)
• Enzymes that harm the host or prevent detection (trick or distract host)
• Proteins that disrupt normal cellular function (ex. replicate in the phagosome)
• Capsule
• Enzymes that inactivate antibiotics (beat out competitors)
Major mechanism that bacteria use to acquire new virulence factors - Answer Horizontal
gene transfer, they can even transform non-pathogens into pathogens!
Horizontal gene transfer: transformation, conjugation, transduction and transposition - Answer
• Transformation - naked/dead DNA picked up by cell
• Conjugation - sex pili used
• Transduction - bacteriophage
• Transposition - "jumping genes" copy + pasting from genomes
Genomic island - Answer When a whole block of DNA is transferred by HGT from one
organism to another, and is integrated into the host chromosome
Pathogenicity island - Answer If the genomic island increases the fitness of a microbe in its
host (virulence factors)
Identification of a pathogenicity island - Answer Pathogenicity islands look different
compared to the rest of the genome (such as having a lower GC content)
Typically flagged by phage or plasmid genes
, Adhesins - Answer Any microbial virulence factor that are required for attachment
Why is attachment required for all microbes that colonize in a host? - Answer To avoid being
removed from the organism
Which monomers make up pili adhesion molecules - Answer Pilin protein
Which region of pili is assembled first, what does it have on it? - Answer The tip of the pili is
assembled first at the cell surface it contains the adhesin protein that binds to host receptors
Which region of a pili interacts with host receptors? - Answer The tip, as it contains the
adhesin protein that binds to host receptors
Type I pili - Answer Static, hairlike appendages used only for
attachment (think: velcro, adhesion only)
Type IV pili - Answer Dynamic, thin, and flexible for "twitching
motility", also energetically expensive (think: fishing rods, adhesion and motility)
Are all adhesions pili? - Answer Nope! Different adhesins enable attachment to different
tissues, and determine the host species and cell types these bacteria will attach and colonize!
Know that most bacteria colonizing the body will do so as.... - Answer Biofilms
Surfaces which biofilms can form on in the body - Answer Organic (ex. lungs, bladder, skin,
stomach lining) or inorganic (ex. catheters and surgical implants)
What is quorum sensing? - Answer Cell-to-cell communication which enables biofilms to
coordinate behavior, positive feedback loops
Why do biofilm-forming infections lead to chronic infections, which will also lead to chronic
inflammation? - Answer The presence of biofilms chronically activates Toll-Like receptors and
triggers inflammation, biofilms also generally resist host defenses and antimicrobial compounds
Order of bacterial pathogenesis (extracellular bacteria) - Answer 1) entry into the body
2) adhesion to host cell surface or tissue
3) colonization
