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Flashcards in 100 Semifinal Past Paper Questions Deck (103)
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1

Which one of the following substrates cannot contribute to net gluconeogenesis in mammal liver?

  • alanine
  • palmitate
  • alpha ketoglutarate
  • glutamate
  • pyruvate

Palmitate

 

 

(only the odd-chain fatty acids can produce propionyl-CoA, which is the only possible glucogenic part of fatty acids)

2

Glycolysis in the erythrocyte produces pyruvate that is further metabolized to

  • CO2
  • lactate
  • glucose
  • hemoglobin
  • ethanol

lactate

 

(no MTC in RBC's)

3

An enzyme used in both glycolysis and gluconeogenesis:

  • hexokinase
  • glucose 6-phosphatase
  • 3-phosphoglycerate kinase
  • phosphofructokinase-1
  • pyruvate kinase

3-phosphoglycerate kinase

 

(one of the reversible steps of glycolysis)

4

Which steps of gluconeogenesis are irreversible? (MULTIPLE ANSWERS)

  1. conversion of fructose-6 phosphate to fructose 1,6 bisphosphate
  2. conversion of glucose-6 phosphate to glucose
  3. reaction catalyzed by pyruvate kinase
  4. conversion of pyruvate to phosphoenolpyruvate
  5. reaction catalyzed by phosphoglycerate kinase

A: 2, 4    B: 1, 2, 4    C: 2,4,5    D: 2,3,4    E: 2

A: 2, 4

 

(not 100% sure, but many of the irreversible rxns are only for glycolysis, and the reversible rxns are from either pathway)

 

 

 

5

An example of an eicosanoid hormone is:

  • Testosterone
  • Epinephrine
  • Thyroxine
  • Thromboxane
  • Retinoic Acid

Thromboxane

6

Arrange the following reactions in the other that they take place in glycolysis:

  1. conversion of fructose-6-phosphate to fructose-1,6-bisphosphate
  2. conversion of 3 phosphoglycerate to 2 phosphoglycerate
  3. reaction catalyzed by pyruvate kinase
  4. reaction catalyzed by hexokinase
  5. reaction catalyzed by phosphoglycerate kinase

A: 4,1,5,2,3        B: 4,1,2,5,3      C: 4,1,3,2,5

D: 1,5,2,4,3        E: 1,4,5,2,3

A: 4,1,5,2,3

7

Which enzyme catalyzes the first ATP producing step of glycolysis?

  • phosphofructokinase 1
  • hexokinase
  • pyruvate kinase
  • phosphoglycerate mutase
  • phosphoglycerate kinase

phosphoglycerate kinase

 

(pyruvate kinase is 2nd ATP-producing step)

8

If glucose is labeled with 14C at C-1 (the aldehyde carbon) were metabolized in the liver, the first radioactive pyruvate formed would be labeled in:

  1. its carboxyl carbon
  2. its carbonyl carbon
  3. its methyl carbon
  4. both 1 and 3
  5. all 3 carbons

methyl carbon*

 

(not 100% sure, basing this on page 545 of Lehninger)

9

Lipoprotein lipase hydrolyzes triacylglycerols of the following lipoproteins: (multiple answers)

  1. VLDL
  2. nascent chylomicron
  3. mature chylomicron
  4. chylomicron remnant
  5. IDL

A: 3,5     B: 1,3,5     C: 2,3,4

D: 1,3      E: all

 

D: 1, 3

 

(requires ApoC-II)

10

The amount of which enzymes increases following a carbohydrate-rich meal:

  1. Acetyl-CoA Carboxylase
  2. Fatty Acid Synthase
  3. ATP-Citrate Lyase
  4. Glucose-6-Phosphate Dehydrogenase
  5. Malic Enzyme

A: 1,4,5     B: 1,2     C: 1,2,3     D: 2,4,5

E: all listed enzymes

E: All listed enzymes

 

 

(taken directly from Tretter lecture on lipids that NADPH producers are activated by insulin and carbs, and so are the fatty acid synthesizing enzymes)

11

Which of the following is(are) true of the beta-oxidation of long-chain fatty acids?

  1. the enzyme complex that catalyzes the reaction contains biotin
  2. FADH2 serves as an electron carrier
  3. NADH serves as an electron carrier
  4. Oxidation of an 18-carbon fatty acid produces six molecules of propionyl-CoA
  5. Oxidation of a 15-carbon fatty acid produces at least one propionyl-CoA

A: 3,5         B: 1,2,3      C: 1,2,5    

D: 2,3,4      E: 2,3,5

 

E: 2,3,5

 

 

(propionyl-CoA produced only by odd chain fatty acids. biotin is part of carboxylases, important in FA synthesis)

12

The enzyme system for adding double bonds to saturated fatty acids requires all of the following except:

  • molecular oxygen (O2)
  • cytochrome b5
  • ATP
  • NADH
  • a mixed-function oxidase

ATP

 

 

(referring to Stearoyl-CoA desaturase aka delta-9-desaturase)

13

Which of the following pathways involve mitochondrial NADH production?
1.citrate
2. beta-oxidation of fatty acids
3. purine de novo synthesis
4. pyrimidine de novo synthesis

A: 1,2,4
B: 1,2
C: 1,2,3
D: 1,3 
E: 2,4
 

A: 1,2,4

14

Which of the following statements is not true of the pathway by which purine nucleotides are synthesized?

  • the amino acid glycine is one of the precursors
  • deoxyribonucleotides are formed from 5-phosphodeoxyribosyl 1-pyrophosphate
  • inosinate is the purine nucleotide that is the precursor of both adenylate and guanylate
  • CO2 is required for one of the steps in the pathway

deoxyribonucleotides are formed from 5-phosphodeoxyribosyl 1-pyrophosphate

 

(deoxynucleotides come from ribonucleotide reductase rxn of nucleotide diphosphates -> deoxynucleotide diphosphates)

15

Which of the following compounds will be reduced by ribonucleotide reductase?

  • TMP
  • UMP
  • dUDP
  • UDP
  • UTP

UDP

 

(must be a nucleotide diphosphate for RR! )

16

Which of the following states result in hyperuricemia?

  1. Deficiency of glucose-6-phosphatase
  2. Deficiency of hypoxanthine-guanine-phosphoriboysyl transferase
  3. Cancer patients after chemo- and radiation therapy
  4. Deficiency of orotate-phosphoribosyl transferase
  5. Deficiency of PRPP-amidotransferase

A: 1,4,5      B: 1,2,3      C: 3,4,5

D: 1,2        E: 3,4

B: 1, 2, 3

 

(von Gierke disease leads to high Ri5P, HPRT used fo purine salvage rxns, and chemotherapy drugs lead to DNA breakdown and overproduction of purines. other causes: fructose intolerance/phosphate trap, heavy exercise, and PRPP overproduction via mutation and PRPP synthase allosteric inhibition site)

17

Per os administration of uridine is a choice of treatment in case of...

  1. UMP synthase deficiency
  2. Ornitine transcarbamoylase deficiency
  3. Gout if allopurinol treatment causes orotic aciduria
  4. Solid tumors during 6-aza-uridine treatment

A: 2    B: 1,2,3,4      C: 1,4

D: 1,3       E: 2,3

B: 1,2,3,4

 

I don't know why, this past paper says it and so far everything else they've done has been right

18

Transamination of the following amino acids results in formation of citric acid cycle intermediates:

  1. alanine
  2. aspartate
  3. glycine
  4. glutamate

A: 1,2,3       B: 1,3      C: 2,4 

D: 4            E: 1,2,3,4

C: 2,4 

 

 

alanine and glycine can be transformed into pyruvate

19

Which of the following intermediates directly provide N atoms to form nucleotide bases?

  1. Amido group of Gln
  2. Amino group of Glu
  3. Asp
  4. Gly
  5. NH3

A: 1,3,4          B: 4,5       C: 1,2,3

D: 2,3,5         E: 1,3

A: 1,3,4

20

Select the enzymes involved in the pyrimidine salvage reactions?

  1. Thymine phosphorybosyl transferase
  2. Uridine-cytidine kinase
  3. Deoxycytidine kinase
  4. OMP decarboxylase

A: 2,3      B: 2,4      C: 1,2,3

D: 1,4       E: 1,2

A: 2,3

 

 

OMP decarboxylase involved in pyrimidine biosynthesis

thymine salvage is done by thymidine kinase

21

What is the name of the enzyme converting inosine to hypoxantine?

  • Hypoxantine phosphorybosyl transferase
  • inosine phosphatase
  • purine nucleoside phosphorylase
  • inosine kinase
  • xantine oxidase

purine nucleoside phosphorylase

22

The product of the reaction catalyzed by adenosine deaminase is:

  • IMP
  • inosine
  • hypoxantine
  • urate
  • adenine

inosine

23

Which of the following intermediates can be converted to serine in a single step reaction?

  1. Pyruvate
  2. Some citric acid cycle intermediates
  3. Some ornithine cycle intermediates
  4. Gly
  5. Choline

A: 1,2,4,5        B: 2,3,4        

C: 1,4,5      D: 3       E: 4

E: 4

 

 

Only Glycine and the glycolysis intermediate of 3phosphoglycerate (as far as this image shows) can do that in one step

26

Glutamate dehydrogenase catalyzes the following reactions:

  1. Incorporation of NH4+ into the alpha-ketoglutarate
  2. Oxidation of NADPH + H+
  3. ATP -> ADP + Pi
  4. Release of NH4+ from Glu
  5. Release of NH4+ from Gln

A: 1,2,4     B: 3,4,5

C: 1,3,5     D: 1,4

E: all

A: 1,2,4

 

 

Glu dehydrogenase usually produces alphaketoglutarate using NAD+, but can also go in the opposite direction in the presence of high ammonia concentration, using NADPH as a cofactor and taking in free ammonia to form Glu

27

The binding of glucagon to its receptor will lead to:

  • the deactivation of adenylate cyclase
  • the decativation of protein kinase A
  • the deactivation of glycogen phosphorylase
  • activation of phosphodiesterase
  • the activation of phosphorylase kinase

the activation of phosphorylase kinase

28

If a person's urine contains unusally high concentration of urea, which of the following diets has he or she probably been eating recently?

  • Very high carbohydrate, very low protein
  • very low carbohydrate, very high protein
  • very high fat, very low protein
  • very high fat, high carbohydrate, no protein

very low carbohydrate, very high protein

29

Which metabolic pathways might operate simultaneously in long-term starvation in the liver?

  1. glycogen breakdown
  2. glycolysis
  3. glutamine synthesis
  4. ketone body synthesis
  5. fatty acid synthesis

A: 1,3,4     B: 2,3,4

C: 1,3       D: 3,4

E: 2,3

D: 3,4

31

Possible utilization of glucose in erthyrocytes includes:

  1. glycogenesis
  2. aerobic glycolysis
  3. anaerobic glycolysis
  4. pentose phosphate pathway
  5. glucoronic acid pathway

A: 2,4,5     B: 2,4

C: 1,2,4      D: 3,4

E: 1,2,5

D: 3,4

32

Protein Kinase A:

  • converts cAMP to ATP
  • converts ATP to cAMP
  • activates glyocgen synthase
  • activates glycogen phosphorylase
  • deactivates glycogen synthase

deactivates glycogen synthase

 

 

(for glycogen phosphorylase, PKA only activates the glycogen phosphorylase kinase that then activates glycogen phosphorylase)

34

Which of the following statements are false?

  1. Insulin activates glycolysis in liver through decreasing fructose-2,6-bisphosphate levels
  2. epinephrine activates glycolysis in liver through increasing fructose-2,6-bisphosphate levels
  3. Epinephrine activates glycolysis in the heart through increasing fructose-2,6-bisphosphate levels
  4. Glucagon inhibits glycolysis in liver through decreasing fructose-2,6-bisphosphate levels
  5. Glucagon inhibits glycolysis in muscle through decreasing fructose-2,6-bisphosphate levels

A: 2,4,5     B: 1,2,5

C: 1,2,4       D: 1,3,5

E: 4,5

B: 1,2,5