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Biochemistry Test 3 Review
Terms in this set (50)
The inputs to one cycle of the urea cycle are
1 molecule of aspartic acid, 1 molecule of ammonia, 1 molecule of carbon dioxide, 3 molecules of ATP
Histidine is degraded to α-ketoglutarate and is described as a
glucogenic amino acid
Which of the following amino acids is considered as both ketogenic and glucogenic?
A glucogenic amino acid is one which is degraded to
pyruvate or citric acid cycle intermediates
A person with phenylketonuria cannot convert
phenylalanine to tyrosine
Oxidative deamination is the conversion of an amino
acid to a keto acid plus ammonia
An example of a transamination process is
aspartate + α ketoglutarate = glutamate + oxaloacetate
The urine of untreated phenylketuonuric patients contain all the following substances, except
Under normal conditions the kidney excrete a small amount of nitrogen in the form of the ammonium ion rather than as urea. The amount of urinary ammonium ion is greatly increased in patients who suffer from
All transamination reactions require the coenzyme
Pyridoxal phosphate (B6)
Which of the following best describes the step of branched-chain amino acid metabolism that is defective in patients suffering from maple syrup urine disease?
Oxidative decarboxylation of the α-keto acid to produce a CoA derivative
Which of the following enzymes is deficient in patients diagnosed with classic albinism?
A blockage in which of the following steps of phenylalanine metabolism is associated with classical phenylketonuria (PKU)?
Hydroxylation of phenylalanine to tyrosine
Which of the following represents a process that does not play a role in the elimination of free ammonia from the body?
Glutamine hydrolysis by glutaminase
Urea from the urea cycle derives its nitrogen atoms exclusively from which of these two amino acid sources?
Glutamate and aspartate
The nitrogen atoms of urea produced in the urea cycle are derived from
ammonia and aspartic acid
The products of urea cycle are
1 molecule of fumaric acid, 1 molecule of urea, 1 molecule of AMP, 2 molecules of ADP
Which of the following is used as carbon atom source while producing urea in the urea cycle?
Which of the following amino acid do not fall under the category of essential amino acid?
Urea cycle converts
ammonia into a less toxic form
A deficiency in any of the enzymes in the inosine monophosphate (IMP) synthesis pathway would most likely result in a reduction in the de novo production of which of the following nucleotides?
AMP and GMP
Which of the following best describes the activity of allopurinol, a drug used to treat hyperuricemia and its complications, including chronic gout?
It is oxidized to alloxanthine, a suicide inhibitor of xanthine oxidase, resulting in the blockage of uric acid synthesis.
Which of the following best describes the antiproliferative activity of fluorouracil or methotrexate?
Methotrexate functions as a competitive inhibitor of dihydrofolate reductase, thereby blocking the synthesis of tetrahydrofolate.
The sugar in RNA is __________ , the sugar in DNA is __________
Nucleoside is a pyrimidine or purine base that is
Covalently bonded to a sugar
-Can participate in hydrophobic interactions due to its methyl group
-Is replaced by uracil in RNA
-Normally forms two hydrogen bonds with adenine
Which of the following is a purine?
Which enzyme is deficient in Lesch-Nyhan syndrome?
Hypoxanthine guanine phosphoribosyltransferase
Which enzyme is inhibited by the anticancer agent methotrexate?
Adenosine deaminase deficiency causes:
Severe Combined Immunodeficiency Syndrome
A 9-month-old male infant presents to your clinic with delayed motor development. His parents have regularly noticed orange sand-like crystals in his diaper, and a serum urate test reveals hyperuricemia. Which of the following is the most likely diagnosis?
Hypoxanthine-guanine phosphoribosyl-transferase deficiency
When allopurinol is used to treat gout, what does it inhibit?
Fluorouridine is used in treatment of breast cancer, which enzyme is inhibited?
What is the ultimate result of treatment with methotrexate?
Rapidly dividing cells die
Enzyme abnormalities that can lead to hyperuricemia and gout include:
Reduced activity of hypoxanthine-guanine phosphoribosyltransferase
A coenzyme form of tetrahydrofolate is required for:
The synthesis of thymine-containing nucleotides from uracil-containing nucleotides
Which of the following is found in RNA but not DNA?
The glycosidic bonds in DNA and RNA does what
Connect the sugar to the base
A mutation in Ornithine Transcarbamoylase increases the substrate for which of the following?
A five carbon sugar lacking an oxygen at the number 2 carbon is found in
To which word does each letter in the acronym HPLC refer?
High Performance (Pressure) Liquid Chromatography
By which property does the reverse phase column on an HPLC separate molecules?
By which property does the mass spectrometer separate molecules?
m/z (mass to charge ratio)
On a mass spectrometer chromatograms what does the height of the peak tell you about the molecule?
The quantity of the molecule
How much would addition of a proton change the mass of a molecule?
It would add one atomic mass unit
What is the function of a collision cell in a triple quadrupole mass spectrometer?
Coupled with a second MS it aids in the differentiation of molecules with the same m/z
Give an example of a use of an HPLC triple quadrupole mass spectrometer.
Quantification of different molecules for a sample (many examples I used Vit D, antifungals and pain meds in class)
To which word does each letter in the acronym MALDI-TOF refer?
Matrix Assisted Laser Desorption/Ionization- Time Of Flight mass spectrometry
Using MALDI-TOF how would you determine the identification of an unknown organism?
Compare the MALDI-TOF profile of the unknown to a data base of the MALDI-TOF profile of known organisms
Could MALDI TOF be used to determine antimicrobial sensitivities in pathogenic microorganisms?
Yes if you can identify the peak or peaks that correspond with antimicrobial resistance in the microorganism
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