MMG 421 FINAL questions with
complete solutions 2025/2026
this cardinal temperature refers to enzymatic reactions occurring at the maximum rate possible
- correct answer ✔✔optimum temperature
this temperature range consists of membrane gelling, and transport processes so slow that
growth cannot occur - correct answer ✔✔minimum temperature
passing the maximum temperature with which growth can occur affects the cytoplasmic
membrane in what way?
proteins?
overall? - correct answer ✔✔collapse of the cytoplasmic membrane
protein denaturation
thermal lysis
log of the growth rate linearly increases with what temperature scale in what temperature
range? - correct answer ✔✔1/T in the Normal Temperature Range
this slope is unaffected by the nutritional status of the culture medium, but the growth rate is
correspondingly lower in minimal medium at all temperatures - correct answer ✔✔temperature
characteristic slope
E. coli becomes phenotypically auxotrophic for what amino acid when the growth temperature
is above its normal temperature range - correct answer ✔✔methionine
,what causes inactivation of the first enzyme in methionine's biosynthetic pathway - correct
answer ✔✔thermal inactivation
during this phase of growth, the culture experiences a pause in growth due to the shift in
temperature in the same medium - correct answer ✔✔transient lags
what type of lag is experienced in a temperature shift that stays within the normal temperature
range? - correct answer ✔✔none
what does the lag time represent when you adjust the temperature? - correct answer ✔✔the
time required for the organism to adjust pathways and homeoviscous adaptation
polaromonas vacuolata has an optimal growth temperature of what? - correct answer ✔✔≤15
C, specifically at 4C
food spoilage often occurs due to this selection of bacteria class - correct answer
✔✔psychrophiles
this temperature range classification of bacteria contribute to all human pathogens, what is the
group and what is the optimal temperature? - correct answer ✔✔mesophiles, 15-40C
where are hyperthermophiles often cultivated? - correct answer ✔✔geothermal and
hydrothermal vents, bacteria and archaea. Limit of life is 122 °C (still growth at this
temperature)
H. influenzae is an example of this temperature growth range, since it exhibits a narrow range of
growth - correct answer ✔✔stenothermal
methanococcus igneous grows over a wide range of temperatures, because of this it is classified
as this type of organism - correct answer ✔✔eurythermal
, thermus aquaticus exhibits a higher growth range due to this key enzyme - correct answer
✔✔Taq polymerase
in Brock's experiment at yellow stone national park, what were his findings? - correct answer
✔✔the higher you increased the temperature of the sampling along the thermal gradient, the
less bacteria you found and more archaea. Also, proved that life does exist above 55 °C!
this term refers to the temperature-mediated regulation of ecological niche width in a certain
geographical location - correct answer ✔✔competitive niche exclusion
this stratification of a lake is on the surface and is warm - correct answer ✔✔epilimnion
this stratification of a lake shows rapid temperature change - correct answer ✔✔thermocline
this stratification of a lake is classified by being deep and cool - correct answer ✔✔hypolimnion
Temperature up-shift outside of growth range activates expression of what genes? - correct
answer ✔✔rpoH and rpoE
What is the level of increase for heat shock proteins with the expression of rpoH and rpoE
genes? - correct answer ✔✔10-20 fold
True or False:
Increase in thermostability results from major changes in amino acid residues? - correct answer
✔✔Falso! Only subtle changes are made and there is still an increase in thermostability. Ex:
Acetyltransferse in Bacillus stearothermophilus differs by only one amino acid.
complete solutions 2025/2026
this cardinal temperature refers to enzymatic reactions occurring at the maximum rate possible
- correct answer ✔✔optimum temperature
this temperature range consists of membrane gelling, and transport processes so slow that
growth cannot occur - correct answer ✔✔minimum temperature
passing the maximum temperature with which growth can occur affects the cytoplasmic
membrane in what way?
proteins?
overall? - correct answer ✔✔collapse of the cytoplasmic membrane
protein denaturation
thermal lysis
log of the growth rate linearly increases with what temperature scale in what temperature
range? - correct answer ✔✔1/T in the Normal Temperature Range
this slope is unaffected by the nutritional status of the culture medium, but the growth rate is
correspondingly lower in minimal medium at all temperatures - correct answer ✔✔temperature
characteristic slope
E. coli becomes phenotypically auxotrophic for what amino acid when the growth temperature
is above its normal temperature range - correct answer ✔✔methionine
,what causes inactivation of the first enzyme in methionine's biosynthetic pathway - correct
answer ✔✔thermal inactivation
during this phase of growth, the culture experiences a pause in growth due to the shift in
temperature in the same medium - correct answer ✔✔transient lags
what type of lag is experienced in a temperature shift that stays within the normal temperature
range? - correct answer ✔✔none
what does the lag time represent when you adjust the temperature? - correct answer ✔✔the
time required for the organism to adjust pathways and homeoviscous adaptation
polaromonas vacuolata has an optimal growth temperature of what? - correct answer ✔✔≤15
C, specifically at 4C
food spoilage often occurs due to this selection of bacteria class - correct answer
✔✔psychrophiles
this temperature range classification of bacteria contribute to all human pathogens, what is the
group and what is the optimal temperature? - correct answer ✔✔mesophiles, 15-40C
where are hyperthermophiles often cultivated? - correct answer ✔✔geothermal and
hydrothermal vents, bacteria and archaea. Limit of life is 122 °C (still growth at this
temperature)
H. influenzae is an example of this temperature growth range, since it exhibits a narrow range of
growth - correct answer ✔✔stenothermal
methanococcus igneous grows over a wide range of temperatures, because of this it is classified
as this type of organism - correct answer ✔✔eurythermal
, thermus aquaticus exhibits a higher growth range due to this key enzyme - correct answer
✔✔Taq polymerase
in Brock's experiment at yellow stone national park, what were his findings? - correct answer
✔✔the higher you increased the temperature of the sampling along the thermal gradient, the
less bacteria you found and more archaea. Also, proved that life does exist above 55 °C!
this term refers to the temperature-mediated regulation of ecological niche width in a certain
geographical location - correct answer ✔✔competitive niche exclusion
this stratification of a lake is on the surface and is warm - correct answer ✔✔epilimnion
this stratification of a lake shows rapid temperature change - correct answer ✔✔thermocline
this stratification of a lake is classified by being deep and cool - correct answer ✔✔hypolimnion
Temperature up-shift outside of growth range activates expression of what genes? - correct
answer ✔✔rpoH and rpoE
What is the level of increase for heat shock proteins with the expression of rpoH and rpoE
genes? - correct answer ✔✔10-20 fold
True or False:
Increase in thermostability results from major changes in amino acid residues? - correct answer
✔✔Falso! Only subtle changes are made and there is still an increase in thermostability. Ex:
Acetyltransferse in Bacillus stearothermophilus differs by only one amino acid.
