MICR 271 Final - Mod 5 Questions and
All Solved Solutions.
what is role of microbes in ocean? - Answer basis of food chain, and can decompose waste
generated by others
how do marine microbes interact with host? - Answer lyse host (bacteria, eukaryotes),
releasing organic matter/nutrients into the environment
what are example of functions of commensal bacteria in plants? - Answer promote plant
growth, prevent pathogen. i.e. bacteria that fix nitrogen (use it to make aa's and nucleotides)
how can behaviour impact microbiomes? - Answer diet can alter biome, also some actions can
result in the release of microbes into the environment
how can microbes impact behaviour? - Answer mating patterns (fruit flies), attraction to
prey /hosts, mood (i.e. anxiety in mice)
what do biofilms in nature consist of? - Answer many different microbes in close proximity,
cells change from planktonic to sessile form.
what process is important for biofilm formation? how does it work - Answer quorum sensing.
bacteria release autoinducers, used to measure density of cells. intraspecies and interspecies
communication occurs.
what is an example of where multispecies biofilms form? what happens? - Answer dental
plaque. commensal bacteria grows, releasing low levels of AI (intraspecies communication does
not need much AI). As biofilm grows, AI levels increase to level that pathogenic bacteria can
detect (interspecies communication). pathogenic can cause erosion of teeth, inflammation
what are examples of abiotic surfaces that biofilm can form on? - Answer rocks, sediments,
indwelling medical devices
how do other organisms utilize biofilm formation? - Answer can be used by organism for
attachment or food (i.e. barnacle)
how does biofilm formation impact medical devices. - Answer growth of biofilms on medical
devices such as catheters disrupts and blocks flow of liquid
,define normal flora - Answer organisms that live on and in the body (commensals)
what is composition of flora based on? - Answer living environment (i.e. hosptial),
geographical location and health
how do newborns acquire microbes? what is this impacted by? - Answer from mothers,
colonize oral and nasopharyngeal cavities, then GI tract. impacted by mode of birth, diet.
how does fungi (mycobiota) play a role in human microbiome? - Answer is apart of normal
flora. has limited diversity on skin but highly diverse on mucosal surfaces. varys more
dramatically. antibiotic use can lead to fungal infection (bacteria can no longer control its
growth, therefore unregulated)
how do bacteria sense their surroundings? - Answer using two-component signal transduction
system
explain the TCST system - Answer stimulus interacts with histidine kinase in membrane,
causing autophosphorylation. sensor protein activated to transfer phosphate to response
regulator in cytoplasm. results in changed conformation, therefore it is able to bind to
chromosome and alter gene expression. gene expression leads to response to stimulus.
what are different targets of bacterial secretion? how to they contribute to ability to cause
disease? - Answer may target environment, surface of bacterial cell or into host cells.
contribute to disease as can relate to immune system evasion, adhesion and nutrient.
explain mechanism of gram-positive sortase system secretion/attachment? - Answer protein
produced in cytoplasm, translocated to periplasm, sortase proteins recognize it (cuts LPXTG
motif) then transfer it to peptidoglycan on surface of cell
what does a protein need to be recognized by sortase system? - Answer signal peptide (gets
protein through cytoplasmic membrane), LPXTG motif (recognized by sortase), positively
charged motif (keeps protein near surface)
define an exotoxin - Answer secreted by bacteria into environment or other cells. toxic to host
define endotoxins - Answer part of bacterial surface, released if bacterial cell is lysed. i.e. LPS
is a common endotoxin that if released into blood causes shock (^ BP, organ failure)
what are the 3 components of the type 1 bacterial secretion system - Answer ABC transporter
(inner membrane), outer membrane protein form channel in outer membrane, membrane
, fusion protein connects ABC transporter and channel. therefore, able to secrete protein in
single step
what is an example of something secreted by the type 1 secretion system? - Answer
Haemolysin is an exotoxin secreted by this system, forms pores in membrane of RBC's
explain type 3 secretion system - Answer injects proteins directly into the host which either
kills or manipulates host. structure resembles flagellum. direct conduit b/w cytoplasms of
bacterium and host
how to microbes in the gut protect us from pathogens? - Answer i.e. gut microbes prevent
C.difficile from growing. use of antibiotics kills microbes, allowing pathogen to germinate and
release toxins. use of fecal transplant to reestablish normal gut flora
what are the benefits of the human microbiome? - Answer protection from pathogens,
nutrient acquisition (help degrade nutrients, release vitamins)
how can the microbiome be perturbed? what can this lead to? - Answer antibiotics, major diet
changes, health issues. can reduce diversity and number of microbes
define dysbiosis and its implications. - Answer can be defined as a major change in
microbiome composition (result of perturbed gut). impacts nutrient absorption, immune system
(inflammation - impact barrier function), autoimmune diseases
define a pathogen - Answer infectious microbes that can cause disease
define pathogenicity - Answer ability of an organism to cause disease
define virulence - Answer measure of severity of the infection that a pathogen can cause
define susceptibility - Answer how easily host can be infected (impacted by previous infection,
vaccines, immune deficiencies)
what type of cells does HIV target? what is normal role of these cells? - Answer CD4 T cells.
cells normally help other immune cells destroy infectious agents
what type of Baltimore class is HIV - Answer type VI ?
All Solved Solutions.
what is role of microbes in ocean? - Answer basis of food chain, and can decompose waste
generated by others
how do marine microbes interact with host? - Answer lyse host (bacteria, eukaryotes),
releasing organic matter/nutrients into the environment
what are example of functions of commensal bacteria in plants? - Answer promote plant
growth, prevent pathogen. i.e. bacteria that fix nitrogen (use it to make aa's and nucleotides)
how can behaviour impact microbiomes? - Answer diet can alter biome, also some actions can
result in the release of microbes into the environment
how can microbes impact behaviour? - Answer mating patterns (fruit flies), attraction to
prey /hosts, mood (i.e. anxiety in mice)
what do biofilms in nature consist of? - Answer many different microbes in close proximity,
cells change from planktonic to sessile form.
what process is important for biofilm formation? how does it work - Answer quorum sensing.
bacteria release autoinducers, used to measure density of cells. intraspecies and interspecies
communication occurs.
what is an example of where multispecies biofilms form? what happens? - Answer dental
plaque. commensal bacteria grows, releasing low levels of AI (intraspecies communication does
not need much AI). As biofilm grows, AI levels increase to level that pathogenic bacteria can
detect (interspecies communication). pathogenic can cause erosion of teeth, inflammation
what are examples of abiotic surfaces that biofilm can form on? - Answer rocks, sediments,
indwelling medical devices
how do other organisms utilize biofilm formation? - Answer can be used by organism for
attachment or food (i.e. barnacle)
how does biofilm formation impact medical devices. - Answer growth of biofilms on medical
devices such as catheters disrupts and blocks flow of liquid
,define normal flora - Answer organisms that live on and in the body (commensals)
what is composition of flora based on? - Answer living environment (i.e. hosptial),
geographical location and health
how do newborns acquire microbes? what is this impacted by? - Answer from mothers,
colonize oral and nasopharyngeal cavities, then GI tract. impacted by mode of birth, diet.
how does fungi (mycobiota) play a role in human microbiome? - Answer is apart of normal
flora. has limited diversity on skin but highly diverse on mucosal surfaces. varys more
dramatically. antibiotic use can lead to fungal infection (bacteria can no longer control its
growth, therefore unregulated)
how do bacteria sense their surroundings? - Answer using two-component signal transduction
system
explain the TCST system - Answer stimulus interacts with histidine kinase in membrane,
causing autophosphorylation. sensor protein activated to transfer phosphate to response
regulator in cytoplasm. results in changed conformation, therefore it is able to bind to
chromosome and alter gene expression. gene expression leads to response to stimulus.
what are different targets of bacterial secretion? how to they contribute to ability to cause
disease? - Answer may target environment, surface of bacterial cell or into host cells.
contribute to disease as can relate to immune system evasion, adhesion and nutrient.
explain mechanism of gram-positive sortase system secretion/attachment? - Answer protein
produced in cytoplasm, translocated to periplasm, sortase proteins recognize it (cuts LPXTG
motif) then transfer it to peptidoglycan on surface of cell
what does a protein need to be recognized by sortase system? - Answer signal peptide (gets
protein through cytoplasmic membrane), LPXTG motif (recognized by sortase), positively
charged motif (keeps protein near surface)
define an exotoxin - Answer secreted by bacteria into environment or other cells. toxic to host
define endotoxins - Answer part of bacterial surface, released if bacterial cell is lysed. i.e. LPS
is a common endotoxin that if released into blood causes shock (^ BP, organ failure)
what are the 3 components of the type 1 bacterial secretion system - Answer ABC transporter
(inner membrane), outer membrane protein form channel in outer membrane, membrane
, fusion protein connects ABC transporter and channel. therefore, able to secrete protein in
single step
what is an example of something secreted by the type 1 secretion system? - Answer
Haemolysin is an exotoxin secreted by this system, forms pores in membrane of RBC's
explain type 3 secretion system - Answer injects proteins directly into the host which either
kills or manipulates host. structure resembles flagellum. direct conduit b/w cytoplasms of
bacterium and host
how to microbes in the gut protect us from pathogens? - Answer i.e. gut microbes prevent
C.difficile from growing. use of antibiotics kills microbes, allowing pathogen to germinate and
release toxins. use of fecal transplant to reestablish normal gut flora
what are the benefits of the human microbiome? - Answer protection from pathogens,
nutrient acquisition (help degrade nutrients, release vitamins)
how can the microbiome be perturbed? what can this lead to? - Answer antibiotics, major diet
changes, health issues. can reduce diversity and number of microbes
define dysbiosis and its implications. - Answer can be defined as a major change in
microbiome composition (result of perturbed gut). impacts nutrient absorption, immune system
(inflammation - impact barrier function), autoimmune diseases
define a pathogen - Answer infectious microbes that can cause disease
define pathogenicity - Answer ability of an organism to cause disease
define virulence - Answer measure of severity of the infection that a pathogen can cause
define susceptibility - Answer how easily host can be infected (impacted by previous infection,
vaccines, immune deficiencies)
what type of cells does HIV target? what is normal role of these cells? - Answer CD4 T cells.
cells normally help other immune cells destroy infectious agents
what type of Baltimore class is HIV - Answer type VI ?
