MCB4403 EXAM 1 FSU questions well
answered to pass
high levels of *polyunsaturated fatty acids* to *increase* membrane fluidity - correct answer
✔✔Increased pressure and cold temps decrease membrane fluidity. What characteristics of
basophiles allow them to survive in deep ocean?
iron pumps to *excrete Na+* and replace it with K+ (another cation) - correct answer ✔✔What
characteristics of specifically *halophiles* allow them to survive in hypertonic salty
environments?
*synthesize or import solutes* that increase osmolarity without disrupting metabolism - correct
answer ✔✔How do some bacteria survive in *hyper*tonic environments? (high external cell
pressure)
contain mechanosensitive channels that activate in hypotonic medium and allow *solutes to
escape* - correct answer ✔✔How do some bacteria survive in *hypo*tonic environments?
(high internal cell pressure)
-high content of tetraether lipids in their membranes that decrease proton permeability
-proton extrusion methods - correct answer ✔✔How do acidophiles maintain a higher pH than
their environments?
-cell surface barrier
-cell wall has *acidic polymers* and *excess of hexosamines* in peptidoglycan - correct answer
✔✔How do alkaliphiles survive in low pH environments?
, recruit cations (Na+ or K+) - correct answer ✔✔E.coli can counter *proton influx* in acidic
environments by
H+/Na* antiporters to *recruit* protons while expelling Na+ - correct answer ✔✔at alkaline
extremes, bacterial cells use _____
consumes, produces - correct answer ✔✔Cells can change the pH of the medium by various
amino acid decarboxylases and deaminases. E.coli ____ weak acids at low pH (acidic) but ____
weak acids at high pH (alkaline).
weak acids - correct answer ✔✔adding ____ to foods undermines bacterial pH homeostasis,
preventing food spoilage.
Reactive O2 species (ROS) - correct answer ✔✔some strict anaerobes die because they are
vulnerable to ___ produced by their own metabolism in the presence of oxygen.
NADH-dehydrogenase 2, FAD cofactor - correct answer ✔✔any organism that possesses _____
will autoxidize the ____ within the enzyme and produce dangerous amounts of superoxide
radical.
H2O2 - correct answer ✔✔superoxide will degrade to ___, another reactive molecule.
iron - correct answer ✔✔___ can also catalyze a reaction with H2O2 to produce the toxic
hydroxyl radical.
superoxide dismutase, peroxidase, and catalase - correct answer ✔✔3 enzymes that destroy
ROS (aerobes have them)
Aerotolerant anaerobes - correct answer ✔✔___ use only fermentation but contain all 3
enzymes that destroy ROS.
answered to pass
high levels of *polyunsaturated fatty acids* to *increase* membrane fluidity - correct answer
✔✔Increased pressure and cold temps decrease membrane fluidity. What characteristics of
basophiles allow them to survive in deep ocean?
iron pumps to *excrete Na+* and replace it with K+ (another cation) - correct answer ✔✔What
characteristics of specifically *halophiles* allow them to survive in hypertonic salty
environments?
*synthesize or import solutes* that increase osmolarity without disrupting metabolism - correct
answer ✔✔How do some bacteria survive in *hyper*tonic environments? (high external cell
pressure)
contain mechanosensitive channels that activate in hypotonic medium and allow *solutes to
escape* - correct answer ✔✔How do some bacteria survive in *hypo*tonic environments?
(high internal cell pressure)
-high content of tetraether lipids in their membranes that decrease proton permeability
-proton extrusion methods - correct answer ✔✔How do acidophiles maintain a higher pH than
their environments?
-cell surface barrier
-cell wall has *acidic polymers* and *excess of hexosamines* in peptidoglycan - correct answer
✔✔How do alkaliphiles survive in low pH environments?
, recruit cations (Na+ or K+) - correct answer ✔✔E.coli can counter *proton influx* in acidic
environments by
H+/Na* antiporters to *recruit* protons while expelling Na+ - correct answer ✔✔at alkaline
extremes, bacterial cells use _____
consumes, produces - correct answer ✔✔Cells can change the pH of the medium by various
amino acid decarboxylases and deaminases. E.coli ____ weak acids at low pH (acidic) but ____
weak acids at high pH (alkaline).
weak acids - correct answer ✔✔adding ____ to foods undermines bacterial pH homeostasis,
preventing food spoilage.
Reactive O2 species (ROS) - correct answer ✔✔some strict anaerobes die because they are
vulnerable to ___ produced by their own metabolism in the presence of oxygen.
NADH-dehydrogenase 2, FAD cofactor - correct answer ✔✔any organism that possesses _____
will autoxidize the ____ within the enzyme and produce dangerous amounts of superoxide
radical.
H2O2 - correct answer ✔✔superoxide will degrade to ___, another reactive molecule.
iron - correct answer ✔✔___ can also catalyze a reaction with H2O2 to produce the toxic
hydroxyl radical.
superoxide dismutase, peroxidase, and catalase - correct answer ✔✔3 enzymes that destroy
ROS (aerobes have them)
Aerotolerant anaerobes - correct answer ✔✔___ use only fermentation but contain all 3
enzymes that destroy ROS.
