CHEM 1005 UPDATED 2026 STUDY GUIDE QUESTIONS AND
SOLUTIONS GRADED A+
✔✔Several amino acids are intermediates of the urea cycle, having side ammonia
groups that join with free carbon dioxide (CO2) and ammonia to produce net excretion
of ammonia as urea. Which of the following amino acids has a nitrogen in its side chain
and is an intermediate of the urea cycle? - ✔✔Arginine
✔✔A newborn infant was resuscitated at birth and was found to be neurologically
compromised, with marked flaccidity (lack of muscle tone), and cardiac insufficiency.
Glutamine was largely absent from the serum and ammonia levels were excessively
elevated and urea production was otherwise not impaired. Based on this information
which of the following enzymes is likely deficient in this infant? - ✔✔Glutamine
synthetase
✔✔Which of the following statements is consistent with nitrogen transport in the fasted
state? - ✔✔The urea cycle will be active
✔✔The transamination of all amino acids requires which of the following cofactors? -
✔✔Pyridoxal phosphate (PLP)
✔✔Which of the following enzymes is correctly paired with its activator? - ✔✔N-
acetylglutamate synthtase; arginine
✔✔Which of the following non-essential amino acids is synthesized as part of the urea
cycle? - ✔✔Arginine
✔✔The urea cycle takes place in which of the following subcellular locations? - ✔✔The
cytosol and the mitochondria
✔✔A deficiency in which of the following enzymes will not result in an increase in orotic
acid? - ✔✔N-acetylglutamate synthetase
✔✔In an individual with a deficiency in the branched chain ketoacid dehydrogenase
complex, metabolism of which of the following amino acids would not likely be
impaired? - ✔✔Tyrosine
✔✔A 15-year-old female presents to her pediatrician with concerns over her inability to
sleep, increased feelings of depression and generalized fatigue. A full laboratory work-
up is ordered and based on these findings she is diagnosed with a melatonin deficiency.
Based on this information, metabolism of which of the following amino acids is likely
impaired? - ✔✔Tryptophan
, ✔✔Which of the following best describes the process of transamination? - ✔✔The
transfer of an amino group from an amino acid to a keto-acid.
✔✔A 17-year old female presents to her primary care and is diagnosed with a Vitamin
B12 (cobalamin) deficiency. In this individual, which of the following reactions would be
compromised? - ✔✔Conversion of methyl malonyl-Co A to succinyl-CoA
✔✔A 52-year- old male sought medical help complaining about progressive appearance
of hyperchromic (hyper pigmented) papules on the edge of the second finger of both
hands. He also complained about darkening of urine. Incisional biopsy of one of the
spots on his hands and urine sample tested positive for or homogentisic acid. Based on
these findings a diagnosis of alkaptonuria is made. This diagnosis is consistent with a
deficiency in which of the following enzymes? - ✔✔Homogentisate oxidase
✔✔Which of the following compounds or substrates is required for the synthesis of
tyrosine? (+ indicates the compound is required; - indicates the compound is not
required)
Tetrahydrofolate (THF) Tetrahydrobiopterin (BH4) Tryptophan Phenylalanine
1. + + + -
2. - + + -
3. + - - +
4. - + - + - ✔✔4. - + - +
✔✔An infant is normal at birth but becomes lethargic after several feedings. The
assigned nurse describes an unusual smell to the urine but is ignored. Infection (sepsis)
is suspected, and blood tests show normal white blood cell counts with a serum pH of
7.0. Evaluation for an inborn error of metabolism shows an abnormal amino acid
screen. The report states that branch-chain amino acids are strikingly elevated.
Elevation of which of the following amino acids would be consistent with the report? -
✔✔Isoleucine
✔✔S-adenosylmethionine (SAM) is synthesized from ATP and methionine. A deficiency
in which of the following enzymes would impair the production of SAM? - ✔✔Methionine
adenosyltransferase (MAT)
✔✔The regulation of PRPP synthetase is critical in the production of both purines and
pyrimidines. This enzyme is inhibited under which of the following conditions? -
✔✔When both GDP and ADP are elevated
✔✔The ribonucleotide reductase is important for converting ribose bases to the deoxy
form. This conversion is coupled with the oxidation of which of the following
compounds? - ✔✔Thioredoxin
SOLUTIONS GRADED A+
✔✔Several amino acids are intermediates of the urea cycle, having side ammonia
groups that join with free carbon dioxide (CO2) and ammonia to produce net excretion
of ammonia as urea. Which of the following amino acids has a nitrogen in its side chain
and is an intermediate of the urea cycle? - ✔✔Arginine
✔✔A newborn infant was resuscitated at birth and was found to be neurologically
compromised, with marked flaccidity (lack of muscle tone), and cardiac insufficiency.
Glutamine was largely absent from the serum and ammonia levels were excessively
elevated and urea production was otherwise not impaired. Based on this information
which of the following enzymes is likely deficient in this infant? - ✔✔Glutamine
synthetase
✔✔Which of the following statements is consistent with nitrogen transport in the fasted
state? - ✔✔The urea cycle will be active
✔✔The transamination of all amino acids requires which of the following cofactors? -
✔✔Pyridoxal phosphate (PLP)
✔✔Which of the following enzymes is correctly paired with its activator? - ✔✔N-
acetylglutamate synthtase; arginine
✔✔Which of the following non-essential amino acids is synthesized as part of the urea
cycle? - ✔✔Arginine
✔✔The urea cycle takes place in which of the following subcellular locations? - ✔✔The
cytosol and the mitochondria
✔✔A deficiency in which of the following enzymes will not result in an increase in orotic
acid? - ✔✔N-acetylglutamate synthetase
✔✔In an individual with a deficiency in the branched chain ketoacid dehydrogenase
complex, metabolism of which of the following amino acids would not likely be
impaired? - ✔✔Tyrosine
✔✔A 15-year-old female presents to her pediatrician with concerns over her inability to
sleep, increased feelings of depression and generalized fatigue. A full laboratory work-
up is ordered and based on these findings she is diagnosed with a melatonin deficiency.
Based on this information, metabolism of which of the following amino acids is likely
impaired? - ✔✔Tryptophan
, ✔✔Which of the following best describes the process of transamination? - ✔✔The
transfer of an amino group from an amino acid to a keto-acid.
✔✔A 17-year old female presents to her primary care and is diagnosed with a Vitamin
B12 (cobalamin) deficiency. In this individual, which of the following reactions would be
compromised? - ✔✔Conversion of methyl malonyl-Co A to succinyl-CoA
✔✔A 52-year- old male sought medical help complaining about progressive appearance
of hyperchromic (hyper pigmented) papules on the edge of the second finger of both
hands. He also complained about darkening of urine. Incisional biopsy of one of the
spots on his hands and urine sample tested positive for or homogentisic acid. Based on
these findings a diagnosis of alkaptonuria is made. This diagnosis is consistent with a
deficiency in which of the following enzymes? - ✔✔Homogentisate oxidase
✔✔Which of the following compounds or substrates is required for the synthesis of
tyrosine? (+ indicates the compound is required; - indicates the compound is not
required)
Tetrahydrofolate (THF) Tetrahydrobiopterin (BH4) Tryptophan Phenylalanine
1. + + + -
2. - + + -
3. + - - +
4. - + - + - ✔✔4. - + - +
✔✔An infant is normal at birth but becomes lethargic after several feedings. The
assigned nurse describes an unusual smell to the urine but is ignored. Infection (sepsis)
is suspected, and blood tests show normal white blood cell counts with a serum pH of
7.0. Evaluation for an inborn error of metabolism shows an abnormal amino acid
screen. The report states that branch-chain amino acids are strikingly elevated.
Elevation of which of the following amino acids would be consistent with the report? -
✔✔Isoleucine
✔✔S-adenosylmethionine (SAM) is synthesized from ATP and methionine. A deficiency
in which of the following enzymes would impair the production of SAM? - ✔✔Methionine
adenosyltransferase (MAT)
✔✔The regulation of PRPP synthetase is critical in the production of both purines and
pyrimidines. This enzyme is inhibited under which of the following conditions? -
✔✔When both GDP and ADP are elevated
✔✔The ribonucleotide reductase is important for converting ribose bases to the deoxy
form. This conversion is coupled with the oxidation of which of the following
compounds? - ✔✔Thioredoxin
