Micro 303 Exam test questions and
answers graded A+
Methanogens - ANS✅✅-archaea
-many diverse species
-obligate anaerobes
produce methane
Methanogenesis - ANS✅✅-a type of anaerobic respiration
-various electron donors are possible (common=hydrogen)
-electron acceptor (CO2) is reduced to methane (CH3)
-unique set of C1 carriers and electron carriers
-electron transfer generates PMF or NaMF, used to make ATP via ATP synthase
B (in the mouth) - ANS✅✅Where on the body might you find methanogens, beside the large
intestine?
A. on the skin
B. in the mouth
C. in the respiratory tract
D. nowhere besides the large intestine
C (Fe2+ would be a poor electron acceptor) - ANS✅✅What electron donors cannot pair with
carbon dioxide as a terminal electron acceptor?
A. H2S
B. H2
C. Fe2+
D. They all would work
proton gradient - ANS✅✅-split H2, electrons go to nonreducing hydrogenase, heterodisulfide
acetogens - ANS✅✅-anaerobic bacteria, most are firmicutes
,-use carbon dioxide as electron acceptor, reduce to acetate
-hydrogen is most common donor, others are possible
-acetyl-CoA pathway
methanogens vs acetogens - ANS✅✅-compete for CO2 and H2
-methanogens win when CO2 or Co low
-acetogens win in higher nutrient solutions
syntrophy - ANS✅✅-a metabolic process in which two different organisms cooperate to degrade a
substrate
-often producer organism can't degrade substrate without the participation of the consumer
organism
-cooperation between two organisms
syntrophomonas - ANS✅✅-species that oxidizes butyrate to acetate to make ATP
-unfavorable reaction unless H2 is removed
-methanogen gets rid of H2 (interspecies hydrogen transfer)
-producer needs consumer to remove products
aerobic degradation - ANS✅✅-aerobic respiration predominates
-oxidized products such as carbon dioxide, nitrate, sulfate are produced
-oxygen is quickly consumed
anaerobic degradation - ANS✅✅-nitrate and sulfate respiration where possible
-fermentation: produces partially oxidized products, which can be used by acetogens, methanogens,
and syntrophs
-when sulfate is available, sulfur-reducing bacteria will outcompete methanogens and acetogens
D (both acetogens and methanogens) - ANS✅✅Which type of hydrogen utilizer do you think
predominates in the human colon?
A. sulfur-reducing bacteria
B. acetogens
,C. methanogens
D. Both B and C
symbiosis - ANS✅✅intimate association between two different types of organisms
mutualism - ANS✅✅A relationship between two species in which both species benefit
commensalism - ANS✅✅A relationship between two organisms in which one organism benefits
and the other is unaffected
amensalism - ANS✅✅a relationship between organisms of two different species in which one is
unaffected and the other is negatively impacted by the association
microbial partnerships - ANS✅✅-almost plants and animals have permanent resident, microbial
partners
-ex: normal microbiota
-communities of microbes on mucosal surface, in body cavity, in specific organs
-sometimes are intracellular symbionts
metaorganisms - ANS✅✅-the community of interacting biological entities that is indicated by a
metagenome
-aka superorganism
holobiont - ANS✅✅-host plus its microbiota
hologenome - ANS✅✅-host genome plus microbiome (microbiota genome)
symbiotic microbes - ANS✅✅-manipulate host animals: germ-free animals and gnotobiotic animals
-animal model systems: drosophila and C. elegans; mice and zebrafish
-microbiome analysis: sequence and analyze
functions of symbiotic microbes - ANS✅✅-assimilation of major nutrients: carbon, nitrogen,
phosphorus
, -provision of minor but essential nutrients: amino acids and vitamins
-protection from predators or parasites or environmental stresses
-role in reproduction
-role in normal physiology: neurological, digestive
-role in development: especially development of the immune system
gnotobiotic animals - ANS✅✅-put known set of microbiota in sterile animals
assimilation of major nutrients - ANS✅✅-microbes fix CO2
-can measure carbon incorporation into animal tissue (microbes provide majority of the carbon)
-ex: clam
provision of minor essential nutrients - ANS✅✅-animals often can't make their own amino acids or
vitamins
-get these essential metabolites from their diet or from symbiotic microbes
-many animals have an incomplete food source: blood lacks vitamins, grains/plants lack amino acids,
xylem/phloem diet lack amino acids
-microbial biosynthetic endosymbionts commonly observed in insects
primary endosymbiont - ANS✅✅-generally obligate for insect and symbiont
-generally intracellular
-often specific organ (bacteriome)
-often specific cells (bacteriocytes)
-provide amino acids and/or vitamins to host
-usually vertical transmission
symbiont mediated protection - ANS✅✅-microbes that produce protective compounds for host
defense
-antibiotics, protein toxins, pigments
-microbes may also facilitate "protection" against other environmental stresses (heat, etc)
-host provides microbes with shelter and food
answers graded A+
Methanogens - ANS✅✅-archaea
-many diverse species
-obligate anaerobes
produce methane
Methanogenesis - ANS✅✅-a type of anaerobic respiration
-various electron donors are possible (common=hydrogen)
-electron acceptor (CO2) is reduced to methane (CH3)
-unique set of C1 carriers and electron carriers
-electron transfer generates PMF or NaMF, used to make ATP via ATP synthase
B (in the mouth) - ANS✅✅Where on the body might you find methanogens, beside the large
intestine?
A. on the skin
B. in the mouth
C. in the respiratory tract
D. nowhere besides the large intestine
C (Fe2+ would be a poor electron acceptor) - ANS✅✅What electron donors cannot pair with
carbon dioxide as a terminal electron acceptor?
A. H2S
B. H2
C. Fe2+
D. They all would work
proton gradient - ANS✅✅-split H2, electrons go to nonreducing hydrogenase, heterodisulfide
acetogens - ANS✅✅-anaerobic bacteria, most are firmicutes
,-use carbon dioxide as electron acceptor, reduce to acetate
-hydrogen is most common donor, others are possible
-acetyl-CoA pathway
methanogens vs acetogens - ANS✅✅-compete for CO2 and H2
-methanogens win when CO2 or Co low
-acetogens win in higher nutrient solutions
syntrophy - ANS✅✅-a metabolic process in which two different organisms cooperate to degrade a
substrate
-often producer organism can't degrade substrate without the participation of the consumer
organism
-cooperation between two organisms
syntrophomonas - ANS✅✅-species that oxidizes butyrate to acetate to make ATP
-unfavorable reaction unless H2 is removed
-methanogen gets rid of H2 (interspecies hydrogen transfer)
-producer needs consumer to remove products
aerobic degradation - ANS✅✅-aerobic respiration predominates
-oxidized products such as carbon dioxide, nitrate, sulfate are produced
-oxygen is quickly consumed
anaerobic degradation - ANS✅✅-nitrate and sulfate respiration where possible
-fermentation: produces partially oxidized products, which can be used by acetogens, methanogens,
and syntrophs
-when sulfate is available, sulfur-reducing bacteria will outcompete methanogens and acetogens
D (both acetogens and methanogens) - ANS✅✅Which type of hydrogen utilizer do you think
predominates in the human colon?
A. sulfur-reducing bacteria
B. acetogens
,C. methanogens
D. Both B and C
symbiosis - ANS✅✅intimate association between two different types of organisms
mutualism - ANS✅✅A relationship between two species in which both species benefit
commensalism - ANS✅✅A relationship between two organisms in which one organism benefits
and the other is unaffected
amensalism - ANS✅✅a relationship between organisms of two different species in which one is
unaffected and the other is negatively impacted by the association
microbial partnerships - ANS✅✅-almost plants and animals have permanent resident, microbial
partners
-ex: normal microbiota
-communities of microbes on mucosal surface, in body cavity, in specific organs
-sometimes are intracellular symbionts
metaorganisms - ANS✅✅-the community of interacting biological entities that is indicated by a
metagenome
-aka superorganism
holobiont - ANS✅✅-host plus its microbiota
hologenome - ANS✅✅-host genome plus microbiome (microbiota genome)
symbiotic microbes - ANS✅✅-manipulate host animals: germ-free animals and gnotobiotic animals
-animal model systems: drosophila and C. elegans; mice and zebrafish
-microbiome analysis: sequence and analyze
functions of symbiotic microbes - ANS✅✅-assimilation of major nutrients: carbon, nitrogen,
phosphorus
, -provision of minor but essential nutrients: amino acids and vitamins
-protection from predators or parasites or environmental stresses
-role in reproduction
-role in normal physiology: neurological, digestive
-role in development: especially development of the immune system
gnotobiotic animals - ANS✅✅-put known set of microbiota in sterile animals
assimilation of major nutrients - ANS✅✅-microbes fix CO2
-can measure carbon incorporation into animal tissue (microbes provide majority of the carbon)
-ex: clam
provision of minor essential nutrients - ANS✅✅-animals often can't make their own amino acids or
vitamins
-get these essential metabolites from their diet or from symbiotic microbes
-many animals have an incomplete food source: blood lacks vitamins, grains/plants lack amino acids,
xylem/phloem diet lack amino acids
-microbial biosynthetic endosymbionts commonly observed in insects
primary endosymbiont - ANS✅✅-generally obligate for insect and symbiont
-generally intracellular
-often specific organ (bacteriome)
-often specific cells (bacteriocytes)
-provide amino acids and/or vitamins to host
-usually vertical transmission
symbiont mediated protection - ANS✅✅-microbes that produce protective compounds for host
defense
-antibiotics, protein toxins, pigments
-microbes may also facilitate "protection" against other environmental stresses (heat, etc)
-host provides microbes with shelter and food
