BIOL 438 Exam 2 Practice Questions and Correct Answers
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Course
BIO 438
Institution
BIO 438
What is the direct consequence of bacteria that cannot make their cell walls correctly because of antibiotics that inhibit cell wall synthesis? The bacteria tend to lyse due to osmosis.
Which answer best explains why antibiotics targeting the cell wall of bacteria have few side effects on people? ...
BIOL 438 Exam 2 Practice Questions and
Correct Answers
What is the direct consequence of bacteria that cannot make their cell walls correctly
because of antibiotics that inhibit cell wall synthesis? ✅The bacteria tend to lyse due to
osmosis.
Which answer best explains why antibiotics targeting the cell wall of bacteria have few
side effects on people? ✅Peptidoglycan is a compound that is unique to bacteria and
those antibiotics targeting bacterial cell walls are unlikely to target any compounds that
people have in or on their cells.
Nitrogen becomes the terminal hydrogen acceptor at the end of the electron transport
chain. ✅Dissimilatory nitrate reduction
Nitrogen is incorporated into the biomass of the organism. ✅Assimilatory Nitrate
Reduction
The synthesis of sugars often requires that the sugar be bound to which molecule?
✅UDP
Gluconeogenesis ✅synthesis of glucose-6-phosphate and/ or glucose from other
compounds (reverse of glycolysis)
-7 enzymes are the same as glycolysis
-4 unique enzymes
Ex: lactate is converted to glucose in the liver by this
several sugar mono and polysaccharides are synthesized from sugars attached to what
✅nucleotide diphosphates (UDPG)
Peptidoglycan Synthesis ✅-involves UDP derivatives
-uses bactoprenol to transport NAG-NAM-pentapeptide units across the membrane
- the crosslink are formed by transpeptidation
, Steps of Peptidoglycan synthesis ✅First step: UDP derivatives of NAM and NAG are
formed
Second step: then, amino acids are added sequentially to NAM to for the pentapeptide
chain
Third step: NAM-pentapeptide is then transferred to bactoprenol phosphate, located at
te cytoplasmic side of the plasma membrane
Autolysins ✅- carry out limited digestion of peptidoglycan
- activity allows new material to be added to wall and division to occur
Sources of nitrogen (inorganic) ✅ammonia, nitrate, nitrite or N2
-most common is ammonia or nitrate
-incorporated into most organic material as NH3 (NH4+)
N can be directly assimilated by ✅-glutamate dehydrogenase
-glutamine synthetase synthase systems
- can be transferred to other carbon skeletons by transaminases
What is the advantage of the glutamate synthase- glutamine synthetase pathway?
✅by coupling assimilation of NH3 to ATP hydrolysis, the glutamate synthase-
glutamine synthetase pathway enables the cells to scavenge NH# more efficiently when
it is present at low concentrations
Assimilatory Nitrate Reduction ✅reduce nitrate to ammonia which is incorporated into
organic metabolites
nitrate reduction to nitrite is catalyzed by ✅nitrate reductase
Nitrogen Fixation ✅Reduction of atmospheric nitrogen to ammonia
- catalyzed by nitrogenase (only in bacteria and archaea)
-large ATP expenditure
3 steps to reduce N2 to NH3
Nucleotide ✅A purine or pyrimidine base joined with a pentose sugar, either ribose or
deoxyribose with one or more phosphate groups.
Nucleoside ✅A purine or pyrimidine base joined with a pentose sugar, either ribose or
deoxyribose.
During fatty acid synthesis, fatty acid synthase will elongate the fatty acid by the
addition of ____ carbon(s) each cycle. ✅2
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