2nd Sem - 1st Evals Batch 2018 Flashcards by Kristine Veneracion

____ True of the metabolism of amino acids:
A. essential amino acids can be formed from other amino acids supplied in the diet
B. excess dietary amino acids cannot be converted to other metabolites
C. excess dietary amino acids that cannot be oxidized are stored as muscle proteins
D. essential amino acids cannot be formed from other amino acids but must be supplied in the diet

How well did you know this?

Not at all

Perfectly

____ True statement about the role of glutamate dehydrogenase: A. has a FAD prosthetic group
B. has a pyridoxal phosphate cofactor
C. transaminates glutamate producing –ketoglutarate
D. oxidatively deaminates glutamate producing –ketoglutarate

How well did you know this?

Not at all

Perfectly

3. \_\_\_\_ Which of the following statements about transamination reactions is correct?
A. involve ATP hydrolysis
B. are irreversible reactions
C. require NAD+ or NADP+
D. require pyridoxal-5’-phosphate

How well did you know this?

Not at all

Perfectly

____ Correct statement about the urea cycle
A. arginosuccinate is lysed to urea and ornithine in the urea cycle
B. carbamoyl phosphate supplies both of the nitrogen atoms of urea in the urea cycle
C. formation of urea from urea cycle yields energy
D. arginine is hyrdrolysed to urea & ornithine in the urea cycle

How well did you know this?

Not at all

Perfectly

____ Which of the following statements about amino acid and protein metabolism is true?
A. most amino acids are both ketogenic and glucogenic
B. both sulphur containing amino acids are essential amino acids
C. aminotransferase enzymes require pyridoxal phosphate as a co-enzyme
D. average man has a store of about 1kg of free amino acids

How well did you know this?

Not at all

Perfectly

____ Which metabolic abnormality gives rise to the serious disease phenylketonuria?
A. homocysteine cannot be converted into methionine
B. phenylalanine cannot be converted into tyrosine
C. phenylalanine cannot be converted into alanine
D. tyrosine cannot be converted into phenylalanine

How well did you know this?

Not at all

Perfectly

____ Which of the following statements about the deamination of amino acids is correct?
A. directly deaminated by dehydrogenation reactions
B. deaminated by two-step transdeamination process
C. deaminated by transferring their amino groups to oxaloacetate
D. deaminated by irreversible transamination reactions

How well did you know this?

Not at all

Perfectly

____ Which of the following statements about the mechanism of transamination reactions is correct?
A. ATP hydrolysis is used to transfer the amino group on the Schiff base to the carbonyl group of keto acid receptor
B. first step of a transamination reaction is the formation of a Schiff base between pyridoxal-5’-phosphate and the carbonyl group of the keto acid
C. first step of a transamination reaction is the formation of a Schiff base between the carbonyl group of pyridoxal-5’-phosphate and the amino group of the amino acid
D. first step of a transamination reaction is the formation of a Schiff base between pyridoxamine phosphate and the keto acid

How well did you know this?

Not at all

Perfectly

____ All of the following statements about the carbon skeletons of amino acids are correct, EXCEPT:
A. ketogenic amino acids can give rise to acetyl-CoA
B. glucogenic amino acids can give rise to glucose in starvation
C. ketogenic amino acids give rise to glucose
D. some amino acids are both glucogenic and ketogenic

How well did you know this?

Not at all

Perfectly

10. \_\_\_\_ What is the name of the enzyme that catalyzes the final step of the urea cycle where arginine is converted to urea and ornithine?
A. arginase
B. ornithine transcarbamoylase
C. arginosuccinase
D. carbamoyl phosphate synthetase

How well did you know this?

Not at all

Perfectly

____ Fish get rid of toxic ammonia by excreting it as _______________.
a. uric acid
b. urea
c. ammonia
d. nitrate

How well did you know this?

Not at all

Perfectly

12. \_\_\_\_ During amino acid catabolism in muscle tissue, toxic ammonia is converted to \_\_\_\_\_\_\_\_\_\_\_\_, which is then transported to the liver where it is deaminated to yield pyruvate and ammonia, which then enters the urea cycle.
A. Glutamic acid 
B. Aspartic acid 
C. Alanine 
D. Glycine

How well did you know this?

Not at all

Perfectly

____ Though all amino acids carry at least one ammonia-equivalent, we know that one specific amino acid is the primary amino acid for transport of ammonia equivalents between tissues. We know this to be true because
A. the gamma-glutamyl cycle amino acid transport system is limited to transporting just one specific amino acid
B. of which one amino acid accumulates in cases of deficient urea synthesis
C. one amino acid makes up half or more of all the amino acids in the blood
D. ammonia can only be released directly from one specific amino acid
E. ammonia can only be incorporated directly into and released directly from one specific amino acid

How well did you know this?

Not at all

Perfectly

____ All L-α-amino acid transamination reactions involve: A. involve decarboxylation
B. involve transfer of a reducing equivalent to NAD+
C. involve tautomerization of a Schiff base
D. release free ammonia

How well did you know this?

Not at all

Perfectly

____ During prolonged fasting of several days, catabolism of amino acids from muscle is the primary source of carbon for generation of
A. carbon dioxide
B. energy (ATP)
C. ketone bodies D. glucose

How well did you know this?

Not at all

Perfectly

____ Citrulline is:
A. an amino acid used to store high energy phosphates in muscle
B. an intermediate in the urea cycle
C. a product of tryptophan metabolism that accumulates when a person is deficient in pyridoxal phosphate
D. a non-essential amino acid because it can be synthesized from an essential amino acid, even though it cannot be synthesized de novo in humans

How well did you know this?

Not at all

Perfectly

____ N-acetylglutamate is:
A. an intermediate in the biosynthesis of ornithine
B. made in the pineal gland and it affects daily cyclical behavior
C. an allosteric activator of the committed step in urea synthesis D. an intermediate in urea synthesis

How well did you know this?

Not at all

Perfectly

____ Homocysteine is:
A. the selenium homologue of cysteine
B. what is left of methionine after it has lost it methyl group C. the oxidized (disulfide) form of cysteine
D. the major donor of methyl groups in cellular metabolism

How well did you know this?

Not at all

Perfectly

19. \_\_\_\_ Dopamine is formed in a reaction that 
A. decarboxylates 5-hydroxytryptophan
B. decarboxylates DOPA
C. hydroxylates phenylalanine
D. hydroxylates tyrosine

How well did you know this?

Not at all

Perfectly

20. \_\_\_\_ Serotonin is made by metabolism of:
A. lysine
B. histidine
C. tryptophan 
D. methionine

How well did you know this?

Not at all

Perfectly

____ Phenylketonuria:
A. is caused by a lack of a monooxygenase enzyme resulting to inability to generate tyrosine
B. results in urine that is or becomes abnormally colored
C. always results from deficiency in enzymes that are needed for synthesis or regeneration of tetrahydrobiopterin
D. All of the above are true

____ Tetrahydrobiopterin is a coenzyme that is essential for:
A. transfer of one-carbon units
B. hydroxylation of certain aromatic amino acids
C. oxidation of sulfur in cysteine
D. oxidative decarboxylation of α-keto carboxylic acids

23. \_\_\_\_ The amino groups of amino acids are disposed off by the body mainly as: 
A. Glutamine 
B. Ammonia 
C. Urea
D. Uric acid

Propionyl-CoA is glucogenic because it is metabolized to:
A. β-hydroxyvaleryl CoA by condensation with acetyl CoA
B. succinyl CoA by bicarbonate addition to the β-carbon
C. succinyl CoA by bicarbonate addition to the α-carbon and subsequent rearrangement
D. pyruvate via oxidation of the α-carbon twice and then hydrolysis of CoA

25. ____ Which of the following enzyme reactions takes place during the synthesis of urea from ammonium ion and glutamate? A. carbamoyl phosphate + citrulline = ornithine B. aspartate + citrulline + ATP = arginosuccinate + AMP + PPi C. arginosuccinate = aspartate + arginine D. CO2 + NH4+ + 2 ADP = carbamoyl phosphate + 2 ATP E. arginosuccinate = arginine + urea

26. ____ All of the following would be expected to increase the activity of the urea cycle EXCEPT: A. antibiotics B. switching to a high protein diet C. going from fed state of a normal diet to a fasting state D. an increase in gluconeogenesis

``` 27. ____ Which of the following is an essential amino acid? A. Alanine B. Glycine C. Valine D. Aspartate ```

``` 28. ____ The products of the catabolism of cysteine are: A. Serine and phosphate B. Pyruvate and sulfate C. Serine and sulfate D. Alanine and sulfate ```

``` 29. ____ All of the following are substrates or products of the phenylalanine hydroxylase reaction, EXCEPT: A. Tetrahydrofolate B. Dihydrobiopterin C. Tyrosine D. O2 ```

``` 30. ____ You suspect that your 12 year old male patient has an inborn error in methionine metabolism. It may be that cystathionine synthase is deficient. If this is the case, he should have high serum concentrations of: A. Methionine B. Cysteine C. Cystathionine D. α-ketobutyrate ```

31. ____ As a result of having the disease phenylketonuria, phenyl ketones are found in the urine. The best explanation for this is: A. Tyrosine hydroxylase is absent and lactate dehydrogenase is absent B. Phenylalanine hydroxylase is absent and aminotransferases are absent C. Phenylalanine hydroxylase is present and tyrosine hydroxylase is absent D. Phenylalanine hydroxylase is absent and aminotransferase are present

32. ____ During a fast, muscle protein is catabolized to free amino acids. All of the following scenarios occur, EXCEPT: A. Alanine travels to the liver & is used for gluconeogenesis B. Glutamine travels to the kidney where its amide group is used to buffer the urine C. Alanine is used for gluconeogenesis in the muscle D. Most amino acids travel to the liver & are used by the liver for gluconeogenesis

33. ____ Which of the statements given about glutamate is NOT true: A. can transfer its amino group to citrulline in a one step reaction B. can be synthesized in the transaminase reaction using alanine as a substrate C. can be synthesized in an aminotransferase reaction using aspartate as a substrate D. can be synthesized by the glutamate dehydrogenase reaction using α-ketobutyrate

``` 34. ____ The urea cycle is regulated by: A. Acetyl CoA B. N-acetylglutamate C. Citrate D. Cytoplasmic carbamoyl phosphate ```

``` 35. ____ The carbon structure of this amino acid can be converted in a single enzyme step into an intermediate in either the TCA cycle or the urea cycle: A. Citrulline B. Aspartate C. Glutamate D. Glutamine ```

``` 36. ____ Serine is a nonessential amino acid. The precursor of glycolysis or of the TCA cycle from which serine is made is: A. Oxaloacetate B. Pyruvate C. 3-phosphoglycerate D. Methionine ```

``` 37. ____ All of the following amino acids are glucogenic EXCEPT: A. Leucine B. Alanine C. Glutamate D. Phenylalanine ```

``` 38. ____ GABA is derived from glutamate by which of the following reactions? A. transamination B. decarboxylation C. deamination D. hydroxylation ```

``` 39. ____ A couple of African-American descent give birth to a girl after an otherwise uneventful pregnancy. The child is exceptionally fair skinned and has almost white hair. Further examination reveals red pupils. A postnatal screen is likely to confirm the deficiency of which of the following enzymes A. glutathione reductase B. glutathione peroxidase C. tyrosinase D. methionine synthase ```

``` 40. ____ Aside from glutamate, these two amino acids are needed to synthesize glutathione, a very important intermediate in amino acid transport: A. methionine & cysteine B. cysteine & glycine C. glycine & ornithine D. methionine & lysine ```

``` 41. ____ Creatinine, a marker of kidney function, is derived from which of the following precursors? A. M, G, R B. R, L, E C. E, C, G D. M, S, G ```

``` 42. ____ AdoMet is required for the synthesis of which of the following compounds? A. thyroxines B. melanin C. serotonin D. phosphatidyl serine ```

``` 43. ____ Which of the compounds named is formed from hydroxylation requiring ascorbate and subsequent methylation? A. histamine B. dopamine C. epinephrine D. creatine ```

``` 44. ____ Which of the following non-essential amino acid is used as a precursor for the synthesis of T3 and T4? A. Y B. E C. T D. S ```

``` 45. ____ A 37-year old woman was diagnosed to have molar pregnancy; after removal of the hydatidiform moles, she was started with methotrexate. This drug inhibits which of the following reactions? A. dopamine to norepinephrine B. dihydrofolate to tetrahydrofolate C. phenylalanine to tyrosine D. tyrosine to Dopa ```

``` 46. ____ In a person with Parkinson’s disease, the monoamine oxidase inhibitor drug given is used to degrade which of the following? A. serotonin B. dopamine C. nicotinamide D. melatonin ```

``` 47. ____ A mother who has a cystathionine β-synthase deficiency just gave birth; which of the following compounds one would most likely expect to be elevated in the blood of the infant at birth if the mother was not treated properly? A. valine B. homocysteine C. threonine D. glutamate ```

``` 48. ____ As a result of liver cirrhosis, ammonia is not properly metabolized by the liver and eventually will affect the brain. Which of the following compounds is expected to be in highest concentration in the brain? A. glutamine B. glutamate C. α-ketoglutarate D. GABA ```

``` 49. ____ Which of the following enzymes need adenosine triphosphate to carry out its reaction? A. argino succinate synthetase B. arginase C. argino succinate lyase D. ornithine transcarbamoylase ```

``` 50. ____ Which of the following amino acids is not converted to acetyl CoA upon catabolism of its carbon skeleton? A. leucine B. tryptophan C. lysine D. valine ```