BIOC 385 Exam 3 || with 100% Verified Solutions.
In the duodenum, enteropeptidase ________________. correct answers cleaves trypsinogen to
form trypsin
Which of the three proteins in the ubiquination pathway is the most responsible for recognizing
the ubiquinated target protein? correct answers E3
What is the regulatory mechanism by which arginine stimulates flux through the urea cycle?
correct answers Arginine stimulates the production of the allosteric activator N-acetylglutamate
A person who has alkaptonuria is easily diagnosed from their black urine. What causes the black
color? correct answers Oxidation of homogentisate
Aspartate is a(n) ________ amino acid, so if a person had a diet that contained no aspartate then
________. correct answers Nonessential; aspartate could be synthesized from other intermediates
What is the mechanism by which glyphosate, the active ingredient in Roundup, kills plants?
correct answers Glyphosate is a competitive inhibitor of plant EPSP synthase.
Phenylketonuria (1) / Albinism (2) is characterized by white skin due to a defect in the enzyme
tyrosinase, which leads to a block in the pathway needed to synthesize adrenaline (3) / melanin
(4). Animals with this condition have an increased risk of skin cancer (5) / mental illness (6). The
genetic disease albinism (7) / phenylketonuria (8) is caused by a defect in the enzyme
phenylalanine hydroxylase, which leads to the accumulation of tyrosine (9) / phenylalanine
(10)derivatives that are toxic metabolites correct answers 2, 4, 5, 8, 10
What molecule signals the endothelial cell to produce NO? correct answers acetylcholine
Angina patients sometimes carry nitroglycerine pills with them___________ correct answers as
a rapid source of NO for blood vessel dilation
Biochemical changes to _______________ regulate protein ubiquitination. correct answers target
proteins and E3 ligases
Compare the function of pepsin with that of secretin. correct answers Pepsin cleaves
polypeptides, whereas secretin neutralizes pH back to 7.
After food enters the stomach, gastrin triggers the release of __________ and secretion of
__________. correct answers gastric juices; pepsinogen
What is the biochemical explanation for why rapid weight loss is reported with protein-rich
diets? correct answers Amino acid degradation results in urea production to remove excess
NH4+, so mostly water weight loss.
, Which of the following amino acids are required in the first step of heme biosynthesis? correct
answers Glycine
The shikimate pathway involves the ________________. correct answers condensation of
phosphoenolpyruvate and erythrose-4-phosphate.
It is important that proteolytic enzymes in the lysosome are optimized to work at low pH because
low pH_____________. correct answers enhances protein denaturing.
What nitrogen source is used to produce carbamoyl phosphate? correct answers ammonia
Regulation of protein ubiquitination is most often mediated by modification of ___________.
correct answers Target proteins and E3 ligases.
Nitrogen obtained from dietary proteins is incorporated into the urea cycle _______. correct
answers Through conversion to aspartate
Alanine, cysteine, glycine, and serine are all considered _____ amino acids. correct answers
Glucogenic
A negative nitrogen balance in a person would be an indicator of ________. correct answers
Starvation.
Arginine, leucine, and lysine are all essential amino acids. This means that they
are____________. correct answers Only available from dietary sources
Why does it make sense that tadpoles (which live in water) have low levels of the enzyme
arginase, but after metamorphosis into frogs (which live on land), their arginase levels increase?
correct answers Tadpoles living in water can excrete ammonia directly, but once on land, they
need to excrete urea.
Which of the following is the reaction for nitric oxide synthase? correct answers L-arginine + 1.5
NADPH + H+ + 2O2 → citrulline + NO + 1.5 NADP+
Nitrogen in biological compounds ultimately comes from ___________. correct answers
Nitrogen gas
In the production of urea, the carbon atom comes from______________. correct answers The
citrate cycle
Why is ingesting large amounts of L-arginine a viable treatment for argininosuccinase
deficiency? correct answers Arginine is converted to ornithine, which provides urea cycle
intermediates Which of the following chemical moieties compost tetrahydrofolate needed for
nitrogen removal.
In the duodenum, enteropeptidase ________________. correct answers cleaves trypsinogen to
form trypsin
Which of the three proteins in the ubiquination pathway is the most responsible for recognizing
the ubiquinated target protein? correct answers E3
What is the regulatory mechanism by which arginine stimulates flux through the urea cycle?
correct answers Arginine stimulates the production of the allosteric activator N-acetylglutamate
A person who has alkaptonuria is easily diagnosed from their black urine. What causes the black
color? correct answers Oxidation of homogentisate
Aspartate is a(n) ________ amino acid, so if a person had a diet that contained no aspartate then
________. correct answers Nonessential; aspartate could be synthesized from other intermediates
What is the mechanism by which glyphosate, the active ingredient in Roundup, kills plants?
correct answers Glyphosate is a competitive inhibitor of plant EPSP synthase.
Phenylketonuria (1) / Albinism (2) is characterized by white skin due to a defect in the enzyme
tyrosinase, which leads to a block in the pathway needed to synthesize adrenaline (3) / melanin
(4). Animals with this condition have an increased risk of skin cancer (5) / mental illness (6). The
genetic disease albinism (7) / phenylketonuria (8) is caused by a defect in the enzyme
phenylalanine hydroxylase, which leads to the accumulation of tyrosine (9) / phenylalanine
(10)derivatives that are toxic metabolites correct answers 2, 4, 5, 8, 10
What molecule signals the endothelial cell to produce NO? correct answers acetylcholine
Angina patients sometimes carry nitroglycerine pills with them___________ correct answers as
a rapid source of NO for blood vessel dilation
Biochemical changes to _______________ regulate protein ubiquitination. correct answers target
proteins and E3 ligases
Compare the function of pepsin with that of secretin. correct answers Pepsin cleaves
polypeptides, whereas secretin neutralizes pH back to 7.
After food enters the stomach, gastrin triggers the release of __________ and secretion of
__________. correct answers gastric juices; pepsinogen
What is the biochemical explanation for why rapid weight loss is reported with protein-rich
diets? correct answers Amino acid degradation results in urea production to remove excess
NH4+, so mostly water weight loss.
, Which of the following amino acids are required in the first step of heme biosynthesis? correct
answers Glycine
The shikimate pathway involves the ________________. correct answers condensation of
phosphoenolpyruvate and erythrose-4-phosphate.
It is important that proteolytic enzymes in the lysosome are optimized to work at low pH because
low pH_____________. correct answers enhances protein denaturing.
What nitrogen source is used to produce carbamoyl phosphate? correct answers ammonia
Regulation of protein ubiquitination is most often mediated by modification of ___________.
correct answers Target proteins and E3 ligases.
Nitrogen obtained from dietary proteins is incorporated into the urea cycle _______. correct
answers Through conversion to aspartate
Alanine, cysteine, glycine, and serine are all considered _____ amino acids. correct answers
Glucogenic
A negative nitrogen balance in a person would be an indicator of ________. correct answers
Starvation.
Arginine, leucine, and lysine are all essential amino acids. This means that they
are____________. correct answers Only available from dietary sources
Why does it make sense that tadpoles (which live in water) have low levels of the enzyme
arginase, but after metamorphosis into frogs (which live on land), their arginase levels increase?
correct answers Tadpoles living in water can excrete ammonia directly, but once on land, they
need to excrete urea.
Which of the following is the reaction for nitric oxide synthase? correct answers L-arginine + 1.5
NADPH + H+ + 2O2 → citrulline + NO + 1.5 NADP+
Nitrogen in biological compounds ultimately comes from ___________. correct answers
Nitrogen gas
In the production of urea, the carbon atom comes from______________. correct answers The
citrate cycle
Why is ingesting large amounts of L-arginine a viable treatment for argininosuccinase
deficiency? correct answers Arginine is converted to ornithine, which provides urea cycle
intermediates Which of the following chemical moieties compost tetrahydrofolate needed for
nitrogen removal.
