Last Biochem Quiz 22

Which of the following statements about maple syrup urine disease is FALSE?I. It is caused by a genetic deficiency in the enzyme BCKDH.II. The disease is fatal unless promptly treated.III. There is a buildup of the branched-chain -keto acids.IV. Patients with the disease excrete urine that smells like maple syrup. I only II only I, III III, IV All of the statements are true.

all statements are true

Excess glucosylation of lens proteins in diabetics leads to cataracts. retinal degeneration. glaucoma. ketosis. fatty liver disease.

cataracts

In which cellular location listed below does the following reaction take place? arginine --> urea + ornithine A. Cytosol B. Mitochondrial matrix C. Lysosome A or B None of the above.

cytosol

Animals lack the ability to produce glucose from ______. other sugars fatty acids pyruvate amino acids starches

fatty acids

In a well-fed state, brain cells use which one of the following compounds circulating in the blood stream almost exclusively as an energy source? amino acids glucose fatty acids ketone bodies insulin

glucose

Adrenalin (epinephrine) is the "fight-or-flight hormone". One of its physiological roles is to mobilize fuel stores in preparation for activity. Given this, which of the following does NOT typically occur in response to the release of adrenalin? Gluconeogenesis in the liver. Glycogen breakdown in the muscle. Glycogen synthesis in the liver. Glycolysis in the muscle.

glycogen synthesis in the liver

Which of the following enzymes is NOT activated by insulin? PFK-2 HMG-CoA reductase Acetyl-CoA carboxylase Glycogen synthase Hormone sensitive lipase

hormone sensitive lipase

In an attempt to lose weight, many people follow a high fat, high protein, low carbohydrate diet. Which of the following substances would NOT have an increased concentration in the blood after two weeks on this diet? urea fatty acids insulin amino acids ketone bodies

insulin

Glucose is the preferred fuel of muscles because it can be metabolized under anaerobic conditions. it can be generated from ketone bodies even during starvation. the heart muscle uses glucose exclusively as a fuel. it is the most efficient energy storage available. All of the above.

it can be metabolize under anaerobic conditions

Glutamate is converted to -ketoglutarate and NH4+ by a process described as: hydrolysis reductive deamination transamination oxidative deamination deamination

oxidative deamination

Which one of the following coenzymes is required in transamination reactions? niacin Coenzyme A NADH pyridoxal phosphate FADH2

pyridoxal phosphate

The interorgan pathway that allows transport of nitrogen from muscle to the liver utilizes ____ as an amino group acceptor in the transamination reaction generating _____. acetyl-CoA; alanine acetyl-CoA; glutamine pyruvate; glutamine pyruvate; glutamate pyruvate; alanine

pyruvate; alanine

The amino acids Ala, Cys, Gly, Ser, and Thr are all degraded to the metabolic intermediate ___ and are considered ____. acetyl-CoA; glucogenic acetyl-CoA; ketogenic pyruvate; glucogenic pyruvate; ketogenic acetoacetate; ketogenic

pyruvate; glucogenic

In humans, which organ is the major site of urea production? the muscle the liver the gastointestinal (GI) tract the kidneys

the liver

Which of the following statements correctly describes nonessential amino acids? They are not used in mammalian proteins. They are synthesized in plants and bacteria but not in humans. They are amino acids other than those required for protein synthesis. They may be substituted with other amino acids in proteins. They can be synthesized in humans as well as in bacteria.

they can be synthesized in humans as well as in bacteria

The neurotransmitters, dopamine, epinephrine, and norepinephrine are synthesized from the amino acid tryptophan tyrosine glutamate aspartate lysine

tyrosine

Which of the following are effects of insulin secretion? I. Muscle and adipose tissue are stimulated to take up glucose. II. Glycogen synthesis increases in the liver. III. Gluconeogenesis is inhibited in the liver and kidney. IV. Lipolysis increases in the adipose tissue. I, II I I, II, III I, III II, IV

1, 2, 3

Which of these amino acids is (are) glucogenic? 1. Isoleucine 2. Valine 3. Leucine 4. Arginine 5. Tyrosine 1, 2, and 5 1, 2, 3, and 5 1, 2, 4, and 5 All None

1, 2, 4, and 5

Which of the following metabolizes ketone bodies?I. brainII. liverIII. muscleIV. adipose tissue I, II, III, IV I, II, III I, III II only III only

1, 3

Which of the following substances, if produced from the catabolism of an amino acid, would be glucogenic (in mammals)? 1. Acetoacetate 2. Pyruvate 3. Acetyl-CoA 4. Oxaloacetate 1 only 4 only 2 and 4 1 and 2 1, 3 and 4

2 and 4

Which one of the following is NOT a type of metabolic "fuel" molecule that can be used by mammalian cells? A. Glucose B. Ketone bodies C. Fatty acids D. Amino acids Options A-D are all metabolic fuel molecules

ALL are correct

Which of the following reactions is catalyzed by adenylate cyclase? ATP cAMP + PPi cAMP AMP ATP cATP ADP cAMP + Pi AMP cAMP

ATP cAMP + PPi

Where are triacylglycerols stored in humans under normal conditions? Myocytes Hepatocytes Liver cells Adipocytes

Adipocytes

In which cellular location listed below does the following reaction take place? ornithine + carbamoyl-phosphate ---> citrulline A. Cytosol B. Mitochondrial matrix C. Lysosome A or B None of the above.

B. Mitochondrial matrix

Under maximum exertion, why does skeletal muscle rely upon glycolysis for ATP production? Because the maximum flux of glycolysis greatly exceeds that of oxidative phosphorylation Because the cells are depleted of O2 Because the cells are depleted of citric acid cycle intermediates Because fatty acids are in short supply

Because the maximum flux of glycolysis greatly exceeds that of oxidative phosphorylation

Metabolism in the muscle is controlled hormonally by A. glucagon. B. insulin. C. epinephrine. Both B and C are correct. A, B, C are correct.

Both B and C are correct

During the urea cycle which two intermediates must both be transported across the inner mitochondrial membrane? Citrulline and ornithine Carbamoyl phosphate and ornitinine Carbamoyl phosphate and citrulline Orthinine and arginine Citrulline and arginine

Citrulline and ornithine

As redox factors, pterins resemble which coenzyme? NAD+ Biocytin FAD SAM

FAD

Which of the following is secreted from the pancreas when blood glucose levels are low? insulin glucagon epinephrine glucose

Glucagon

Which of the following does NOT typically occur in response to elevated epinephrine levels? Glycolysis in myocytes. Fatty acid mobilization in adipocytes. Glycogen breakdown in hepatocytes. Gluconeogenesis in hepatocytes. Glycogen synthesis in myocytes.

Glycogen synthesis in myocytes.

Which of the following control the urea cycle?I. substrate concentration of the cycle enzymesII. allosteric activation of carbamoyl phosphate synthetase IIII. concentration of glutamateIV. availability of glucose I, III II, III II, IV I, II, III I, IV

I, II, III

Ketogenic amino acids can be converted toI. glucoseII. fatty acidsIII. ketone bodiesIV. pyruvate I, III II, III I, II I, II, III I, IV

II, III

Which of the following best describes the function of AMP-dependent protein kinase (AMPK)? It activates ATP-generating metabolic pathways and inhibits biosynthetic pathways. It activates biosynthetic pathways and inhibits ATP-generating metabolic pathways. It activates both ATP-generating and biosynthetic pathways. It inhibits both ATP-generating and biosynthetic pathways. None of the above is correct.

It activates ATP-generating metabolic pathways and inhibits biosynthetic pathways.

Where are the two major sites of glucose storage in humans? Brain and kidney. Muscle and adipose tissue. Liver and brain. Liver and adipose tissue. Liver and muscle.

Liver and muscle

What species are combined to produce carbamoyl phosphate? NH3 , PO43−, HCO3− NH4+, PO43−, Ac-CoA, releasing CoA-SH glycine & inorganic phosphate, releasing CO2 acetate & NH4+, releasing CO2 alanine & inorganic phosphate, releasing acetate

NH3 , PO43−, HCO3−

_____ catalyzes the synthesis of ____, a molecule that signals vasodilation, from the precursor _____ NOS; nitric oxide (NO); arginine Nitrous oxidase; nitrous oxide; arginine Arginate; nitric oxide (NO); citrulline Citrulline dehydrogenase; nitrous oxide; citrulline None of the above

NOS; nitric oxide (NO); arginine

Which of the following is TRUE in the liver after a meal rich in carbohydrates? Acetyl-CoA levels fall and the rate of cholesterol synthesis decreases. Gluconeogenesis is activated and glycolysis is inhibited. Acetyl-CoA levels rise and ketone body synthesis increases. Oxaloacetate levels are high and citrate synthesis increases.

Oxaloacetate levels are high and citrate synthesis increases.

Branched-chain -keto acid dehydrogenase is a multi-enzyme complex that resembles which other enzymes? Pyruvate dehydrogenase and citrate synthase Pyruvate dehdyrogenase and A-ketoglutarate dehydrogenase Malate dehydrogenase and A-ketoglutarate dehydrogenase Pyruvate dehydrogenase and succinate dehydrogenase

Pyruvate dehdyrogenase and A-ketoglutarate dehydrogenase

What is the purpose of the Cori cycle? To provide an energy advantage of one extra ATP per round through glycolysis. To degrade excess lactate and prevent acidosis of the muscle tissue. To remove lactate from the muscle and transport it to the liver where it can undergo gluconeogenesis. To transport pyruvate back to the liver for gluconeogenesis.

To remove lactate from the muscle and transport it to the liver where it can undergo gluconeogenesis.

If a person's urine contains unusually high concentrations of urea, which of the following diets has he or she probably been eating recently? Very high carbohydrate, no protein, no fat. Very low carbohydrate, very high protein. Very high fat, high carbohydrate, no protein. High carbohydrate, very low protein. Very high fat, very low protein.

Very low carbohydrate, very high protein.