Exam 2 Biol 3370 Microbial Biology Utah
Study Guide Exam Questions And
Answers.
Psychrophile - Answer Low temperature optima (4°)
Mesophiles - Answer Midrange temperature optima(15-35°)
Thermophils - Answer High temperature optima(45-80°)
Hypothermophiles - Answer Very high temperature optima (>88°)
Psychotolerant - Answer Can grow at 0°C
Acidophiles - Answer <5.5 pH, optimum at 1,3,5
Neutrophile - Answer 5.5<pH<8, optimum 7
Alkaliphile - Answer pH>8, optimum 8,9,10
Water activity - Answer Low water activity can be a problem when lots of salt is on the
outside, water flows out and creates a negative water balance
Compatible solutes - Answer When organism is transferred from medium of high water
activity to low water activity, it maintians a positive balance by increasing its internal solute
concentration
Aerobes - Answer Can grow at full oxygen tensions (air is 21% O2) and respire O2 in their
metabolism
Microaerophiles - Answer Aerobes that can use O2 only when it is present at levels reduced
from that in air (microoxic conditions)
, Anaerobes - Answer Cannot respire oxygen
Aerotolerant Anaerobes - Answer Tolerate O2 and grow in presence even though they cannot
respire
Obligate Anaerobes - Answer Inhibited or even killed off by O2
Thioglycolate - Answer A reducing agent, a complex medium that reacts with O2 and O2 can
only penetrate near the top of the tube where the medium contacts air. Redox indicator dye
resazurin is present in broth to signal oxic regions, gives visual representation of how much O2
has penetrated medium.
Catabolite repression(glucose effect) - Answer Mechanism of global control that controls the
use of carbon sources if more than one is present. Prevents expression of most other catbolic
operons as long as glucose is present. As long as glucose is present, lac operon is not expressed
and lactose is not used
Diauxic growth - Answer When glucose is present, cell will grow rapidly, then there is a pause
in the growth, and then cell continues to grow on lactose but at a slower rate
CyclicAMP - Answer Regulatory nucleotide, a key molecule in many metabolitic control
systems. Synthesized from ATP by an anezye called adenylate cyclase. Glucose inhibits the
synthesis of cAMP and promotes exiting the cell.
CRP - Answer Cylic AMP receptor protein
Process of Lac operon - Answer Active repressor Lac I, when there is cAMP it binds to CRP,
which recruits RNA polymerase. This allows transcription of Lac Z, Lac Y, and Lac A which all lead
to lactose catabolism. So when there is glucose, lactose catabolism is nonexistent
Sigma factors - Answer Bind Rna Polymerase, several alternative sigma factors exist that
recognize different consensus sequences. Each alternative sigma factor is specific for a group of
genes required under special circumstances and thus essential for regulating gene exprsesion
σP - Answer Everyday genes
Study Guide Exam Questions And
Answers.
Psychrophile - Answer Low temperature optima (4°)
Mesophiles - Answer Midrange temperature optima(15-35°)
Thermophils - Answer High temperature optima(45-80°)
Hypothermophiles - Answer Very high temperature optima (>88°)
Psychotolerant - Answer Can grow at 0°C
Acidophiles - Answer <5.5 pH, optimum at 1,3,5
Neutrophile - Answer 5.5<pH<8, optimum 7
Alkaliphile - Answer pH>8, optimum 8,9,10
Water activity - Answer Low water activity can be a problem when lots of salt is on the
outside, water flows out and creates a negative water balance
Compatible solutes - Answer When organism is transferred from medium of high water
activity to low water activity, it maintians a positive balance by increasing its internal solute
concentration
Aerobes - Answer Can grow at full oxygen tensions (air is 21% O2) and respire O2 in their
metabolism
Microaerophiles - Answer Aerobes that can use O2 only when it is present at levels reduced
from that in air (microoxic conditions)
, Anaerobes - Answer Cannot respire oxygen
Aerotolerant Anaerobes - Answer Tolerate O2 and grow in presence even though they cannot
respire
Obligate Anaerobes - Answer Inhibited or even killed off by O2
Thioglycolate - Answer A reducing agent, a complex medium that reacts with O2 and O2 can
only penetrate near the top of the tube where the medium contacts air. Redox indicator dye
resazurin is present in broth to signal oxic regions, gives visual representation of how much O2
has penetrated medium.
Catabolite repression(glucose effect) - Answer Mechanism of global control that controls the
use of carbon sources if more than one is present. Prevents expression of most other catbolic
operons as long as glucose is present. As long as glucose is present, lac operon is not expressed
and lactose is not used
Diauxic growth - Answer When glucose is present, cell will grow rapidly, then there is a pause
in the growth, and then cell continues to grow on lactose but at a slower rate
CyclicAMP - Answer Regulatory nucleotide, a key molecule in many metabolitic control
systems. Synthesized from ATP by an anezye called adenylate cyclase. Glucose inhibits the
synthesis of cAMP and promotes exiting the cell.
CRP - Answer Cylic AMP receptor protein
Process of Lac operon - Answer Active repressor Lac I, when there is cAMP it binds to CRP,
which recruits RNA polymerase. This allows transcription of Lac Z, Lac Y, and Lac A which all lead
to lactose catabolism. So when there is glucose, lactose catabolism is nonexistent
Sigma factors - Answer Bind Rna Polymerase, several alternative sigma factors exist that
recognize different consensus sequences. Each alternative sigma factor is specific for a group of
genes required under special circumstances and thus essential for regulating gene exprsesion
σP - Answer Everyday genes
