UNE Medical Biochemistry Unit 4 Questions & Answers
Which of the following statements is consistent with nitrogen transport in the
fasted state?
Glutaminase will be inactive
The urea cycle will be active
Hepatic glutamate dehydrogenase will primarily produce glutamate
Transport of alanine from skeletal muscle will be reduced
The urea cycle will be active
Which of the following enzymes is likely to be active in both the fed and fasted
states?
Glycogen synthase
Pyruvate kinase
Hormone sensitive lipase
Glutaminase
Glutaminase
Which of the following enzymes is the regulatory step in the urea cycle?
Carbamoyl phosphate synthetase I (CPS I)
Argininosuccinate lyase
Ornithine transcarbamoylase
Arginase
Carbamoyl phosphate synthetase I (CPS I)
A comatose infant is brought to the ER. In the course of the examination, plasma
ammonia was found to be elevated 20-fold over normal values. Urine orotic acid
and uracil were both greater than normal. A defect of which of the following
enzymes is the most likely diagnosis?
Phosphoribosyl pyrophosphate synthetase (PRPP Synthetase)
N-acetylglutamate synthetase
Carbamoyl phosphate synthetase II
Ornithine transcarbamoylase
Carbamoyl phosphate synthetase I
Ornithine transcarbamoylase
The glucose alanine cycle is a method of transferring ammonia from the skeletal
muscle to the liver. In this process the non-toxic carrier of ammonia is which of
the following compounds?
Pyruvate
Urea
Glutamine
Alanine
Alanine
, Ubiquitination is a means of targeting a protein for which of the following cellular
processes?
Proteasomal degradation
Digestion
Protein translation
Storage
Proteasomal degradation
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
Phenylalanine
Methionine
Glutamate
Asparagine
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
Glutaminase
Alanine aminotransaminase
Ornithine transcarbamoylase
Glutamine synthetase
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?
Tyrosine
Tryptophan
Phenylalanine
Valine
Tryptophan
Which of the following amino acids is essential?
Methionine
Tyrosine
Which of the following statements is consistent with nitrogen transport in the
fasted state?
Glutaminase will be inactive
The urea cycle will be active
Hepatic glutamate dehydrogenase will primarily produce glutamate
Transport of alanine from skeletal muscle will be reduced
The urea cycle will be active
Which of the following enzymes is likely to be active in both the fed and fasted
states?
Glycogen synthase
Pyruvate kinase
Hormone sensitive lipase
Glutaminase
Glutaminase
Which of the following enzymes is the regulatory step in the urea cycle?
Carbamoyl phosphate synthetase I (CPS I)
Argininosuccinate lyase
Ornithine transcarbamoylase
Arginase
Carbamoyl phosphate synthetase I (CPS I)
A comatose infant is brought to the ER. In the course of the examination, plasma
ammonia was found to be elevated 20-fold over normal values. Urine orotic acid
and uracil were both greater than normal. A defect of which of the following
enzymes is the most likely diagnosis?
Phosphoribosyl pyrophosphate synthetase (PRPP Synthetase)
N-acetylglutamate synthetase
Carbamoyl phosphate synthetase II
Ornithine transcarbamoylase
Carbamoyl phosphate synthetase I
Ornithine transcarbamoylase
The glucose alanine cycle is a method of transferring ammonia from the skeletal
muscle to the liver. In this process the non-toxic carrier of ammonia is which of
the following compounds?
Pyruvate
Urea
Glutamine
Alanine
Alanine
, Ubiquitination is a means of targeting a protein for which of the following cellular
processes?
Proteasomal degradation
Digestion
Protein translation
Storage
Proteasomal degradation
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
Phenylalanine
Methionine
Glutamate
Asparagine
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
Glutaminase
Alanine aminotransaminase
Ornithine transcarbamoylase
Glutamine synthetase
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?
Tyrosine
Tryptophan
Phenylalanine
Valine
Tryptophan
Which of the following amino acids is essential?
Methionine
Tyrosine
