MCB450 Practice Final Questions

The synthesis of glucose from pyruvate by gluconeogenesis:

a. Occurs exclusively in the cytosol.

b. Requires the oxidation/reduction of FAD.

c. Requires the participation of biotin.

d. Is inhibited by an elevated level of glucagon.

e. Involves lactate as an intermediate.

c. Requires the participation of biotin.

In the non-oxidative stage of the Pentose-PO4 pathway, intermediates of _____________ are produced.

a. The citric acid cycle

b. The citric acid cycle and glycogen degradation

c. Glycolysis

d. Glycolysis and glycogen degradation

e. Glycogen degradation

c. Glycolysis

The synthesis of glucose from pyruvate by gluconeogenesis:

a. Occurs exclusively in the cytosol.

b. Requires the oxidation/reduction of FAD.

c. requires the participation of biotin.

d. Is inhibited by an elevated level of glucagon.

e. Involves lactate as an intermediate.

c. requires the participation of biotin.

Which one of the following is a common intermediate in the conversion of glycerol and lactate to glucose?

a. Pyruvate

b. Glucose 6-phosphate

c. Oxaloacetate

d. Malate

e. Phosphoenol pyruvate

b. Glucose 6-phosphate

Which one of the following reactions is unique to gluconeogenesis?

a. Glucose-6-PO4 to Fructose-6-PO4

b. 1,3-Bis-phosphoglycerate to 3-phosphoglycerate

c. Oxaloacetate to phosphoenolpyruvate

d. Lactate to pyruvate

e. Phosphoenolpyruvate to pyruvate

c. Oxaloacetate to phosphoenolpyruvate

Which of the following would be expected to occur after acute alcohol ingestion?

a. Lactic acidosis

b. An increase in gluconeogenesis

c. An increase in NAD/NADH+ ratio

d. The inhibition of ketogenesis

e. The activation of fatty acid oxidation

a. Lactic acidosis

A 34-year-old woman presents to her physician complaining of oral ulcers. A careful history reveals that she is a strict vegetarian and does not eat meat, fish, O C O poultry, eggs, or dairy products. She is found to have a severe riboflavin deficiency. The function of which enzymes in the TCA cycle would be most directly affected by the riboflavin deficiency?

a. Isocitrate dehydrogenase

b. Succinate dehydrogenase

c. Malate dehydrogenase

d. Citrate synthase

e. Aconitase

b. Succinate dehydrogenase

Mammalian pyruvate dehydrogenase complex (PDC) is inactivated by pyruvate dehydrogenase kinase in the presence of:

a. High AMP

b. High Insulin

c. High NADH

d. High Pyruvate

e. High ADP

c. High NADH

Which lipoprotein particle functions in "reverse" cholesterol transport?

a. HDL

b. Chylomicrons

c. LDL

d. VLDL

e. IDL

a. HDL

Which of these enzymes is primarily responsible for digesting dietary triacylglycerols in the small intestine?

a. Pancreatic lipase

b. Lipoprotein lipase

c. Lingual lipase

d. Hormone-sensitive lipase

e. Gastric lipase

a. Pancreatic lipase

High levels of ATP and citrate:

a. Indicate a high energy-well fed state.

b. Inhibit glycolysis

c. Indicate remote gluconeogenesis

d. All of the above

e. None of the above

d. All of the above

Which of the following would be associated with LOW pyruvate dehydrogenase rate?

a. Low NADH

b. Low Acetyl CoA

c. High NAD+

d. Low NAD+/High NADH

e. High ADP

d. Low NAD+/High NADH

.The hallmarks of acute alcoholism without food intake are acidosis and hypoglycemia. These metabolic changes are due to the:

a. Lack of food uptake (glucose) and the cellular metabolism of alcohol generates high concentration of NADPH, which is favorable for ketoacids production.

b. Metabolism of ethanol, which prevents the production of sufficient levels of blood glucose from glycogen stores.

c. Increase of consumption of alcohol leads to acute inflammation of the liver, which leads to massive consumption of glucose-6-phosphate as an energy source and hypoglycemia in the serum.

d. An increase in the use of the glycolytic pathway. The use of glycolysis rather than the electron transport chain to produce ATP would result in a deficiency of energy in the liver cell.

e. Metabolism of ethanol, which prevents the production of sufficient levels of blood glucose from lactate, glycerol and alanine.

e. Metabolism of ethanol, which prevents the production of sufficient levels of blood glucose from lactate, glycerol and alanine.

Hormonal activation of cyclic AMP levels will:

a. activate protein kinase A phosphorylation of Fructose bisphosphatase

b. Activate the PKC phosphorylation of PFK2.

c. Lead to the activation of PFK.

d. Increase the activation of gluconeogenesis.

e. Phosphorylate PFK2 on a tyrosine residue.

d. Increase the activation of gluconeogenesis.

Which of the following vitamins are precursors to coenzymes that are necessary for the formation of acetyl CoA from pyruvate?

a. Thiamine, riboflavin, niacin, and biotin

b. Thiamine, riboflavin, niacin, lipoic acid, pantothenic acid, and biotin

c. Thiamine, riboflavin, niacin, lipoic acid, and pantothenic acid

d. Thiamine, riboflavin, and lipoic acid

e. None of the above

b. Thiamine, riboflavin, niacin, lipoic acid, pantothenic acid, and biotin

In addition to pyruvate dehydrogenase, what other enzyme(s) in the citric acid cycle has a key thiamine pyrophosphate coenzyme?

a. Citrate synthase

b. Malate dehydrogenase

c. Isocitrate dehydrogenase

d. Aconitase

e. α-ketoglutarate dehydrogenase

e. α-ketoglutarate dehydrogenase

Why does acetyl CoA, a product of fatty acid catabolism, influence the pyruvate dehydrogenase complex (PDH), a control point in carbohydrate catabolism?

a. When fatty acid breakdown is high, ADP is low and PDH is inhibited by phosphatase activity.

b. When fatty acid breakdown is high, NADH levels drop, causing an increase in E2 activity.

c. When fatty acid breakdown is inhibited, PDH is inhibited by acetyl CoA due to phosphatase activity.

d. When fatty acid breakdown is high, PDH is inhibited by acetyl CoA due to pyruvate kinase activity.

e. When fatty acid breakdown is inhibited, ADP is low, causing a decrease in activity.

d. When fatty acid breakdown is high, PDH is inhibited by acetyl CoA due to pyruvate kinase activity.

The citric acid cycle is activated in the presence of oxygen (O2), but what is the link between the citric acid cycle and O2?

a. The presence of O2 in the mitochondrial matrix releases CO2 into the cytosol.

b. The iron-sulfur center requires O2 to be in the appropriate oxidation state. c. O2 is an allosteric activator for citrate synthase.

d. A primary product of the citric acid cycle is NADH, the principle electron donor to the O2, the last electron acceptor in the electron-transport system. e. The one substrate-level phosphorylation in the citric acid cycle can occur in the absence of O2.

d. A primary product of the citric acid cycle is NADH, the principle electron donor to the O2, the last electron acceptor in the electron-transport system.

What is(are) the chemical change(s) involved in the conversion of citrate into isocitrate?

a. Oxidative decarboxylation

b. Oxidation followed by reduction

c. Dehydration followed by hydration

d. Oxidation

e. Hydration followed by dehydration

c. Dehydration followed by hydration

Which of the following conditions will activate pyruvate dehydrogenase kinase, which catalyzes the phosphorylation and inactivation of E1 in the pyruvate dehydrogenase complex?

a. Insulin

b. Elevated concentrations of NADH and ATP

c. Elevated concentrations of acetyl CoA

d. Elevated concentrations of NAD+ and ADP

e. Ca²⁺

b. Elevated concentrations of NADH and ATP

The direct movement of substrates from one enzyme to the next is called:

a. Cell with sufficient available water.

b. Substrate channeling

c. Electron acceptor.

d. Protein complex.

e. Linker coenzyme.

b. Substrate channeling

A mutation in the active site of succinyl CoA synthetase where His is converted to Lys would result in which of the following?

a. Loss of a positively charged amino acid necessary for catalysis

b. Increased stable folding

c. Loss of a succinyl phosphate intermediate

d. All of the above

e. None of the above

c. Loss of a succinyl phosphate intermediate

What are the steps involved (in order) in the conversion of pyruvate to acetyl CoA?

a. Decarboxylation, transfer to CoA, oxidation

b. Oxidation, decarboxylation, transfer to CoA

c. Oxidation, dehydration, transfer to CoA

d. Oxidation, transfer to CoA, decarboxylation

e. Decarboxylation, oxidation, transfer to CoA

e. Decarboxylation, oxidation, transfer to CoA

Approximately how many ATP or GTP equivalents are produced during one turn of the citric acid cycle?

a. 9

b. 12

c. 6

d. 10

e. 32

d. 10

Although we study the citric acid cycle as the final stage of oxidation of carbon from glucose, an in-depth look at the cycle shows intermediates entering and leaving the cycle from a number of metabolic pathways. With all of these demands on the cycle, how does it maintain a minimal level of oxaloacetate (OAA) to allow the cycle to function?

a. OAA is synthesized via pyruvate carboxylase in an anaplerotic reaction that occurs when acetyl CoA is present.

b. OAA can be formed by the condensation of two moles of acetyl CoA and occurs when the energy charge of the cell is high.

c. OAA is formed directly via the deamination of glutamate.

d. The rate of the cycle is increased when the cell has high levels of NADH.

e. Isocitrate dehydrogenase is allosterically inhibited by ADP, which signifies the need for more energy.

a. OAA is synthesized via pyruvate carboxylase in an anaplerotic reaction that occurs when acetyl CoA is present.

A 1-month-old male showed abnormalities of the nervous system and lactic acidosis. Enzyme assay for pyruvate dehydrogenase (PDH) activity on extracts of cultured skin fibroblasts showed 5% of normal activity, with a low concentration (1 x 10-4 mM) of thiamine pyrophosphate (TPP), but 80% of normal activity when the assay contained a high (0.4 mM) concentration of TPP. Which one of the following statements concerning this patient is most correct?

a. Alanine concentration in the blood is expected to be less than normal.

b. The patient is expected to show disturbances in fatty acid degradation.

c. Elevated levels of lactate and pyruvate in the blood reliably predict the presence of PDH deficiency.

d. Administration of thiamine is expected to reduce his serum lactate concentration and improve his clinical symptoms.

e. A diet consisting of high carbohydrate intake would be expected to be beneficial in this patient.

d. Administration of thiamine is expected to reduce his serum lactate concentration and improve his clinical symptoms.

The following is the sum of three steps in the citric acid cycle. A + B + FAD + H2O → C + FADH2 + NADH Choose the lettered answer that corresponds to the missing "A", "B", and "C" in the equation. Reactant A Reactant B Reactant C a. Succinate NAD+ Oxaloacetate

b. Fumarate NAD+ Oxaloacetate

c. Fumarate GTP Malate

d. Succinyl CoA GTP Succinate

e. Succinate NAD+ Malate

a. Succinate NAD+ Oxaloacetate

Which of these compounds is oxidized by a multienzyme complex that requires five different coenzymes?

a. Pyruvate

b. Citrate

c. Malate

d. Isocitrate

e. Succinate

a. Pyruvate

A low level of carbon dioxide labeled with 14C is accidentally released into the atmosphere surrounding industrial workers as they resume work following the lunch hour. Unknowingly, they breathe the contaminated air for 1 hour. Which of the following compounds will be radioactively labeled?

a. About one half of the carbon atoms of newly synthesized fatty acids.

b. One half of the carbon atoms of newly synthesized acetyl CoA.

c. All of the carbon atoms of newly synthesized fatty acid.

d. The carboxyl atom of newly synthesized fatty acids.

e. About one third of the carbons of newly synthesized malonyl CoA.

e. About one third of the carbons of newly synthesized malonyl CoA.

The β-oxidation of myristyl-CoA (14:0) yields:

a. 7 acetyl CoA + 7 FAD + 7 NAD+

b. 7 acetyl CoA + 7 FADH2 + 7 NADH + 7 H+.

c. 6 acetyl CoA + 7 FADH2 + 7 NADH + 7 H+

d. 14 acetyl CoA + 12 FADH2 + 12 NADH + 12 H+.

e. 7 acetyl CoA + 6 FADH2 + 6 NADH + 6 H+.

b. 7 acetyl CoA + 7 FADH2 + 7 NADH + 7 H+.

Fatty acid synthesis is regulated by hormone depending on feeding vs. fasting and recent exercise vs. no recent exercise. Which hormones are active and what is their mechanism of action of the(se) hormone(s) after exercise and a meal?

a. Glucagon activates the carboxylase by enhancing the phosphorylation of AMPK.

b. Insulin stimulates fatty acid synthesis by activating acetyl CoA carboxylase 1 c. Insulin stimulates the mobilization of fatty acids for β oxidation

d. Epinephrine stimulates AMPK, preventing the phosphorylation of acetyl CoA carboxylase 1

e. Epinephrine stimulates the mobilization of fatty acids and stimulates their accumulation as triacylglycerols.

b. Insulin stimulates fatty acid synthesis by activating acetyl CoA carboxylase 1

What are the conditions that lead to a "beer gut" due to the excess consumption of alcohol?

a. Excess ethanol metabolism leads to an accumulation of NADH that inhibits fatty acid metabolism.

b. NADH inhibits ketone body formation, stimulating glucose rather than fatty acid metabolism.

c. NADH produced from the metabolism of ethanol stimulates the citric acid cycle for glucose-derived acetyl CoA.

d. NADH stimulates citric acid cycle enzymes that stimulates glucose-derived acetyl CoA metabolism.

e. The processing of acetate in the liver becomes inefficient leading to a pH imbalance in liver cells, reducing enzyme efficiency in general.

a. Excess ethanol metabolism leads to an accumulation of NADH that inhibits fatty acid metabolism.

A 20-year-old woman with diabetes mellitus was admitted to the hospital in a semiconscious condition with fever, nausea and vomiting. The woman's breath smelled of acetone. A urine sample was strongly positive for ketone bodies. In this patient:

a. An insulin injection would alleviate her ketoacidosis by decreasing ketone body production.

b. The acetone must have been produced by spontaneous decarboxylation of βhydroxybutyrate.

c. The patient should be given an intravenous infusion of glucose to regain consciousness.

d. Glucagon should be administered immediately to stimulate glycogenolysis and gluconeogenesis in the liver.

e. A blood glucose test would likely show that her blood glucose was well below 80 mg/dL.

a. An insulin injection would alleviate her ketoacidosis by decreasing ketone body production.

Increased expression of the enzyme cytochrome P450 2E1 in chronic alcoholics would result in which of the following?

a. A low possibility of the generation of free radicals.

b. A decrease in the rate of acetaldehyde production.

c. A decreased clearance of ethanol from the blood.

d. Protection from liver damage.

e. An increase of one's alcohol tolerance level.

e. An increase of one's alcohol tolerance level.

A person has entered a hunger strike. After five days of starvation, what kind of fuel is being utilized?

a. Protein from the brain and heart

b. Protein from skeletal muscle and fat from adipose tissue

c. Glycogen stored in the liver

d. Glycogen and protein from the liver

e. Glycogen stored in the muscle

b. Protein from skeletal muscle and fat from adipose tissue

A person has entered a hunger strike. After 60 days of starvation, this person is on the edge of dying. What is likely to be the cause of death?

a. Too many ketone bodies in the blood, which causes ketoacidosis

b. Lack of oxygen in the body for oxidative metabolism

c. Shut down of gluconeogenesis in the liver In

d. The breakdown of essential proteins of the brain and heart

e. Exhaustion of fat from adipose tissue

d. The breakdown of essential proteins of the brain and heart

Considering the final steps in cholesterol biosynthesis, when squalene is eventually converted to lanosterol, which of the following statements is wrong?

a. Squalene monooxygenase uses reduced flavin nucleotides, such as FAD(2H), as the cosubstrate in the reaction.

b. Squalene is joined at carbons 1 and 30 to form the fused ring structure of sterols.

c. All of the sterols have three fused rings (the steroid nucleus) and are alcohols with a hydroxyl group at carbon C3.

d. The action of squalene monooxygenase oxidizes C14 of the squalene chain, forming an epoxide.

e. Squalene monooxygenase is considered a mixed function oxidase because it catalyzes a reaction in which only one of the oxygen atoms of O2 is incorporated into the organic substrate

b. Squalene is joined at carbons 1 and 30 to form the fused ring structure of sterols. (If it asks for correct, the answer is e)

A chronic alcoholic is in treatment for alcohol abuse. The drug disulfiram is prescribed for the patient. This drug deters the consumption of alcohol by which of the following mechanisms?

a. Enhancing the conversion of acetaldehyde to acetate, which reduces the inebriating effects of alcohol.

b. Preventing the excretion of acetate, which causes nausea and vomiting.

c. Inhibiting the absorption of ethanol so that an individual cannot become intoxicated, regardless of how much he or she drinks.

d. Inhibiting the conversion of acetaldehyde to acetate, which causes reduced clearance of acetaldehyde.

e. Activating the excessive metabolism of ethanol to acetate, which causes inebriation with consumption of even a small amount of alcohol.

d. Inhibiting the conversion of acetaldehyde to acetate, which causes reduced clearance of acetaldehyde.

A young girl with a history of severe abdominal pain was taken to her local hospital at 5 a.m. in severe distress. Blood was drawn, and the plasma appeared milky, with the triacylglycerol level in excess of 2,000 mg/dl (normal = 4-150 mg/dl). The patient was placed on a diet severely limited in fat, but supplemented with medium-chain fatty acids. Which of the following lipoprotein particles are most likely responsible for the appearance of the patient's plasma?

a. Intermediate-density lipoproteins

b. Chylomicrons

c. Low-density-lipoproteins

d. High-density-lipoproteins

e. Very-low-density lipoproteins

b. Chylomicrons

Medium-chain fatty acids are given because they:

a. Are more calorically dense than long-chain fatty acids.

b. Stimulates VLDL production by the liver.

c. Are activators of lipoprotein lipase.

d. Can be converted into a variety of gluconeogenic precursors.

e. Enter directly into the portal blood, and can be metabolized by the liver.

e. Enter directly into the portal blood, and can be metabolized by the liver.

Which one of the following consequences of chronic alcohol consumption is irreversible?

a. Inhibition of fatty acid oxidation

b. Wernicke-Korsakoff syndrome

c. Hypoglycemia

d. Thiamine deficiency

e. Lactic acidosis

b. Wernicke-Korsakoff syndrome

Most of the enzymes are made of ...

a. Amino acids

b. Carbohydrates

c. ATP

d. Nucleic acids

e. Lipids

a. Amino acids

Lipid functions include all of the following except:

a. Forming the skeletal muscle fibers

b. Plasma membrane structure

c. Long term energy storage

d. Chemical structure of hormones

e. Protection against physical shock

a. Forming the skeletal muscle fibers

Which is the Correct pairing of a tissue with its main fuel source in STARVATION

a. Skeletal muscle - fatty acids

b. Brain - fatty acids

c. Adipose tissue - glucose

d. Liver - glucose

e. Erythrocytes - ketone bodies

d. Liver - glucose

Odd chain fatty acids and some amino acids produce propionyl CoA. Which of the following is NOT required for the metabolism of propionyl CoA to succinyl CoA?

a. NAHD

b. Biotin

c. Propionyl CoA carboxylase

d. Vitamin B12

e. Methylmalonyl CoA

a. NAHD

Humans can convert cholesterol to each of the following, EXCEPT

a. Bile Acids

b. Estradiol

c. CO2 + H2O

d. Testosterone

e. Cortisol

c. CO2 + H2O

Glycolysis and gluconeogenesis are reciprocally regulated by a common regulator, fructose-2,6-bisphosphate. Levels of fructose-2,6-bisphosphate are regulated by

a. Phosphorylation of the PFK-2/FBPase-2 bifunctional enzyme that increases the level of fructose-2,6, bisphosphate 2

b. The bifunctional enzyme PFK-2 and FBPase-2 which is encoded in a single protein

c. Fructose,1,6-bisphosphate which competes for binding to PFK-2 4. Phosphofructokinase-2 (PFK-2) which catalyzes the trans-phosphorylation of fructose-1,6-bisphosphate

d. All of the above

b. The bifunctional enzyme PFK-2 and FBPase-2 which is encoded in a single protein

Mammalian pyruvate dehydrogenase component E1 is inactivated through phosphorylation in the presence of

a. High pyruvate

b. Insulin

c. High Acetyl-CoA

d. High AMP

e. High ADP

c. High Acetyl-CoA

Brian Cooper, a 35-year-old businessman, led a stressful life and didn't exercise. He ate irregularly, smoked, and drank. His physician suspected a heart problem and had tests performed to aid in the diagnosis. Elevated serum levels of low-density lipoproteins (LDL) are indicative of elevated levels of

a. Triacylglycerols

b. Lipoprotein lipase

c. HDL

d. Cholesterol

e. Chylomicrons

d. Cholesterol

Lovastatin was used to treat Brian Cooper. The drug lovastatin works by inhibiting the function of which protein?

a. HMG-CoA reductase

b. Lipoprotein lipase

c. Cyclooxygenase

d. LDL receptor

e. Alcohol dehydrogenase

a. HMG-CoA reductase

In gluconeogenesis, the role of pyruvate kinase (from glycolysis) is replaced by what activities?

a. Production of phosphoenolpyruvate from oxaloacetate

b. Conversion of pyruvate to oxaloacetate by pyruvate carboxylase. Production of phosphoenol pyruvate from oxaloacetate

c. Conversion of pyruvate to oxaloacetate by pyruvate carboxylase

d. Production of phosphoenolpyruvate from pyruvate

e. Production of phosphoenolpyruvate from pyruvate. Conversion of pyruvate to oxaloacetate by pyruvate carboxylase

a. Production of phosphoenolpyruvate from oxaloacetate

Which is TRUE of the reciprocal regulation of glycolysis and gluconeogenesis a. Citrate inhibits Fructose 1,6-bisphosphate and inhibits phosphofructokinase. ADP inhibits Pyruvate carboxylase and activates pyruvate kinase

b. ADP inhibits pyruvate carboxylase and activates pyruvate kinase

c. Citrate inhibits Fructose 1,6-bisphosphatase and inhibits phosphofructokinase

d. ATP inhibits phosphofructokinase and activates Fructose 1,6-bisphosphatase

e. ADP inhibits Pyruvate carboxylase and activates pyruvate kinase. ATP inhibits phosphofructokinase and activates Fructose 1,6-bisphosphatase

d. ATP inhibits phosphofructokinase and activates Fructose 1,6-bisphosphatase

A 20-year-old woman with type 1 diabetes was admitted to the hospital in a semiconscious condition with fever, nausea and vomiting. The woman's breath smelled of acetone. A urine sample was strongly positive for ketone bodies. In this patient:

a. An insulin injection would alleviate her ketoacidosis by decreasing ketone body production

b. The acetone must have been produced by spontaneous decarboxylation of Betahydroxybutyrate

c. A blood glucose test would likely show that her blood glucose was well below 80 mg/dL

d. The patient should be given an intravenous infusion of glucose to regain consciousness

e. Glucagon should be administered immediately to stimulate glycogenolysis and gluconeogenesis in the live

a. An insulin injection would alleviate her ketoacidosis by decreasing ketone body production

During vigorous exercise, stimulation of the tricarboxylic acid (TCA) cycle results principally from

a. A rapid decrease in the concentration of four carbon intermediates being used by other metabolic pathways e.g. gluconeogenesis

b. Stimulation of the flux through a number of TCA cycle enzymes by a decreased NADH/NAD+ ratio

c. Allosteric activation of fumarase by increased cellular ADP concentrations d. Product inhibition of the citrate synthase enzyme, which blocks the condensation of Acetyl CoA and oxaloacetate

e. Allosteric activation of a number of TCA cycle enzymes by increased levels of NADH

b. Stimulation of the flux through a number of TCA cycle enzymes by a decreased NADH/NAD+ ratio

Triacylglycerol synthesis in adipose tissue occurs only in the fed state. It is due to

a. Coenzyme A being required to activate the fatty acids prior to coupling to glycerol-3 phosphate

b. Fatty acid for triacylglycerol synthesis being obtained from chylomicrons and VLDL, which is high in concentration after a meal with high fat content

c. Lipoprotein lipase being activated only in the fed state by Apo-CII

d. The lack of glycerol kinase in adipose tissue that generates glycerol-3- phosphate. Glycerol-3-phosphate is obtained from the glycolytic pathway operated in the fed state with high glucose concentration

d. The lack of glycerol kinase in adipose tissue that generates glycerol-3- phosphate. Glycerol-3-phosphate is obtained from the glycolytic pathway operated in the fed state with high glucose concentration

Tangier disease is characterized by severe plasma deficiency or absence of HDL by accumulation of cholesterol esters in many tissues throughout the body. Which of the following proteins of enzymes is deficient in this condition?

a. Hepatic triglyceride lipase

b. Lipoprotein lipase

c. ABCA1 (ATP binding cassette protein I)

d. ApoB 100

e. LDL receptor

c. ABCA1 (ATP binding cassette protein I)

A patient with a genetic defect in lipoprotein lipase would be expected to exhibit which of the following?

a. Decreased intestinal absorption of fats

b. Decreased recycling of bile salts

c. Elevated chylomicrons in fasting blood samples

d. A deficiency in release of fatty acids from adipocytes during fasting

e. Elevated glucose in fasting blood samples

c. Elevated chylomicrons in fasting blood samples

A 6-month-old boy was hospitalized following a seizure. History revealed that for several days prior, his appetite was decreased due to a "stomach virus". At admission, his blood glucose was 24 mg/dL (age referenced normal is 60-100 gm/dL) His urine was negative for ketone bodies, but positive for a variety of carboxylic acids. A tentative diagnosis of medium-chain fatty acyl CoA dehydrogenase (MCAD) deficiency is made. In patients with MCAD deficiency, the fasting hypoglycemia is a consequence of:

a. Increased production of ATP and NADH

b. Decreased ability to convert acetyl CoA to glucose

c. Increased conversion of acetyl CoA to acetoacetate

d. Demonic anemia

e. Decreased acetyl CoA production

e. Decreased acetyl CoA production

Suppose 14C-labeld CO2 is used to form malonyl-CoA from acetyl-CoA is used for palmitate synthesis, which carbon atom(s) in the fatty acid would be radiolabeled?

a. All odd numbered carbons

b. None of the carbons

c. Only the alpha and beta carbons

d. All even numbered carbons

e. The methyl terminal carbon

b. None of the carbons

Fatty acids are adenylated prior to reacting with Coenzyme A to make Acyl-CoA. Which is the purpose of the adenylation?

a. This creates a phospho-ester bond that can be "attacked" by Coenzyme A b. Adenylation leads to the addition of ATP ot acyl chains

c. Adenylation prevents Acyl-CoA from interacting with Coenzyme A

d. This allows for the growth of acyl chain length

e. All of the above

a. This creates a phospho-ester bond that can be "attacked" by Coenzyme A

In gluconeogenesis aldolase functions to convert on Glyceraldehyde 3-phosphate and one dihydroxyacetone phosphate to the following product(s)? a. One dihydroxyacetone phosphate and an enediolate

b. Fructose 1,6-bisphosphate

c. Fructose 2,6-bisphosphate

d. Two Glyceraldehyde 3-phosphate

e. Fructose 6-phosphate

b. Fructose 1,6-bisphosphate

A 35-year-old woman was seen in the emergency room because of recurrent abdominal pain. The history relieved a 2-year pattern of pain in the upper right quadrant, beginning several hours after the ingestion of a meal rich in fried/fatty food. Ultrasonographic examination demonstrated the presence of numerous stones in the gallbladder. The patient initially elected treatment consisting of exogenously supplied chenodeoxycholic acid, but eventually underwent surgery for the removal of the gallbladder, and had a full recovery. The rationale for the initial treatment of this patient with chenodeoxycholic acid is that this compound:

a. Stimulated VLDL production by the liver

b. Inhibits cholesterol synthesis

c. Interferes with the enterohepatic circulation

d. Increases cholesterol solubility in bile

e. Increases de novo bile acid production

d. Increases cholesterol solubility in bile

The carnitine derivatives of fatty acids are utilized for:

a. One of the intermediates during beta oxidation

b. Transporting fatty acids across the plasma membrane of the cell

c. Carrying fatty acids during fatty acid synthesis

d. Shutting fatty acids across the mitochondrial membrane

d. Shutting fatty acids across the mitochondrial membrane

Glycolysis and the TCA cycle are regulated by the cellular concentrations of ATP, citrate and NADH, which provide a synchronized regulation of these two pathways through their ketone committing enzymes. These enzymes are:

a. Hexose kinase and alpha-ketoglutarate dehydrogenase

b. Phosphofructokinase-1 and isocitrate dehydrogenase

c. Glucokinase and isocitrate dehydrogenase

d. Pyruvate kinase and succinyl CoA dehydrogenase

e. Phosphofructokinase-1 and citrate dehydrogenase

b. Phosphofructokinase-1 and isocitrate dehydrogenase

Which of the following compounds is a potent stimulator palmitate synthesis, an allosteric activator of acetyl-CoA carboxylase, and a source of both cytoplasmic acetylCoA and NADPH for lipogenesis?

a. Pantothenic acid

b. Glucose 6-phosphate

c. L-carnitine

d. Citrate

e. Biotin

d. Citrate

Triacylglycerol molecules stored in adipose tissue represent the major reserve of substrate providing energy during a prolonged fast. During such a fast:

a. The stored fatty acids are released from adipose tissue into the plasma as components of the serum lipoprotein particle, VLDL

b. Hormone-sensitive lipase is phosphorylated and activated by a cAMPactivated protein kinase

c. Glycerol produced by the degradation of triacylglycerol is an important direct source of energy for adipocytes and fibroblasts

d. Free fatty acids are produced at a high rate in the plasma by the action of lipoprotein lipase on chylomicrons

e. Hormone-sensitive lipase is dephosphorylated and deactivated by a protein phosphatase 1

b. Hormone-sensitive lipase is phosphorylated and activated by a cAMPactivated protein kinase

What is the effect of protein kinase A phosphorylation of Fructose 2,6-bisphosphatase?

a. Inhibits the fructose 2,6-bisphosphatase kinase domain

b. Increases glucagon signaling

c. Activates the fructose 2,6-bisphosphatase kinase domain

d. Inhibits both the fructose 2,6-bisphosphatase domain and kinase domain

e. Activates fructose 1,6-bisphosphate phosphatase

d. Inhibits both the fructose 2,6-bisphosphatase domain and kinase domain

Which of the following is responsible for down regulation of fatty acid synthesis under low energy conditions?

a. Release of ATP inhibition of acetyl CoA carboxylase

b. AMP activation of a AMP activated protein kinase (AMPK)

c. AMP activation of PFK-1

d. Release of ATP inhibition of carnitine acyl transferase I

e. AMP activation of PEP carboxykinase (PEPCK)

b. AMP activation of a AMP activated protein kinase (AMPK)

When inhibition occurs mainly because fatty acid biosynthesis is stimulated, beta-oxidation of fatty acids is inhibited. This

a. Malonyl-CoA inhibits carnitine acyltransferase I

b. The pool of acetyl-CoA is depleted by the TCA cycle and fatty acid biosynthesis

c. High levels of citrate stimulate acetyl-CoA synthase

d. High levels of ATP inhibit phosphofructokinase

e. Acetyl-CoA activates pyruvate carboxylase

a. Malonyl-CoA inhibits carnitine acyltransferase I

e. Yes, The presence of acetyl CoA signals the cell that there is an excess of energy. While the acetyl CoA itself cannot be used to form glucose, its presence can activate pyruvate carboxylase which is needed to start gluconeogenesis

Fatty acid synthesis requires the presence of acetyl CoA. Does acetyl CoA affect the process of glucose synthesis (gluconeogenesis)?

a. No. Lipid metabolism and carbohydrate metabolism make use of completely different pathways and there are no connections between the two. Carbohydrates are formed from three carbon precursors and lipids from tow carbon sources

b. No. One thing for certain is that fatty acids (and acetyl CoA made from these fatty acids) cannot be used to synthesize glucose

c. No. Acetyl CoA is formed in the mitochondria either by the action of pyruvate dehydrogenase or the enzymes of fatty acid oxidation. Gluconeogenesis takes place in the cytosol so that these metabolic pathways are separated

d. Yes. burning fatty acids provide both the ATP and the carbon skeletons needed to form glucose. Therefore, the presence of acetyl CoA infors the cell that both energy and carbon are available for gluconeogenesis

e. Yes, The presence of acetyl CoA signals the cell that there is an excess of energy. While the acetyl CoA itself cannot be used to form glucose, its presence can activate pyruvate carboxylase which is needed to start gluconeogenesis

Which of the following statements about chylomicrons is INCORRECT?

a. Intestinal mucosal cells secrete chylomicrons

b. Chylomicrons travel initially through the lymphatic system before reaching the blood

c. The main role of chylomicrons is to deliver cholesterol to the tissues and fatty acids to the liver

d. Lipoprotein lipase hydrolyzes triacylglycerols in chylomicrons

e. Chylomicrons contain phospholipid

c. The main role of chylomicrons is to deliver cholesterol to the tissues and fatty acids to the liver

Why is it important that Biotin be linked to a flexible arm of pyruvate carboxylase?

a. The biotin needs to move between the separated biotin carboxylation and carboxyltransferase sites within the same copy of the protein

b. The biotin needs to move between the separated biotin carboxylation and carboxyltransferase sites between adjacent, copies of the protein in a tetramer

c. The biotin needs to move between the separated biotin decarboxylation and carboxyltransferase sites within the same copy of the protein

d. The biotin needs to move between the separated biotin carboxylation and carboxyltransferase sites between adjacent copies of the protein in a trimer

e. The biotin needs to move between the separated biotin carboxylation and carboxyltransferase sites between adjacent copies of the protein in a dimer

b. The biotin needs to move between the separated biotin carboxylation and carboxyltransferase sites between adjacent, copies of the protein in a tetramer

What is the role of carnitine acyltransferase-I?

a. Transport acyl chains into the mitochondrial matrix

b. Reacts with acyl-carnitine and CoA to transfer the acyl chain to make acyl-CoA Transport Acyl chains into the mitochondrial matrix

c. Reacts with acyl-CoA and L-carnitine to transfer the acyl chain to make acylcarnitine—

d. Reacts with acyl-CoA and L-carnitine to transfer the acyl chaine to make Acylcarnitine. Transport acyl chains into the mitochondrial matrix

e. Reacts with acyl-carnitine and CoA to transfer the acyl chain to make Acyl-CpA-

c. Reacts with acyl-CoA and L-carnitine to transfer the acyl chain to make acylcarnitine—

The TCA cycle feeds into the biosynthesis of various products. Which of the following is NOT true?

a. Citrate feeds into fatty acid and sterol synthesis

b. Alpha-ketoglutarate feeds into purine synthesis

c. Oxalocate feeds into glucose synthesis

d. Succinyl CoA feeds into Heme biosynthesis

e. Malate feeds into amino acid synthesis

e. Malate feeds into amino acid synthesis

Which liver enzyme is active in BOTH the fed and fasted state?

a. Pyruvate carboxylase

b. Pyruvate dehydrogenase

c. PFK-2 (Phosphofructokinase-2)

d. Acetyl-CoA carboxylase

e. Carnitine palmitoyl transferase I

a. Pyruvate carboxylase

Prior to the removal of an acetyl-CoA from an Acyl-CoA in Beta-oxidation, the saturated beta carbon must be

a. Oxidized, hydrated and dehydrated again to form L-3-hydroxyacyl CoA

b. Oxidized, dehydrated and oxidized again to form trans 2-Enoyl CoA

c. Reduced, dehydrated and reduced again to form butyryl ACP

d. Reduced, dehydrated and reduced again to form D 3-hydroxybutyryl ACP e. Oxidized, hydrated and oxidized again to form 3-ketoacyl CoA

e. Oxidized, hydrated and oxidized again to form 3-ketoacyl CoA

The E2 stage of the pyruvate dehydrogenase cascade involves the cofactors TPP and lipoamide. In the illustrated figure below what reaction is going to occur?

a. The Hydroxyethyl-TPP carbanion will attack the lipoamide disulfide bond leading to a covalent intermediate

b. NADH will attack the lipoamide disulfide bond.

c. The TPP carbanion will reduce the lipoamide disulfide bond

d. Reduced Lipoamide will be deprotonated by the carbanion

e. Oxidized lipoamide will deprotonate the hydroxyl from Hydroxyethyl-TPP

a. The Hydroxyethyl-TPP carbanion will attack the lipoamide disulfide bond leading to a covalent intermediate

During Diabetic Ketosis when insulin is absent, fats are released and processed by Betaoxidation. Which of the following statements are TRUE:

a. Acetyl-CoA reacts with oxaloacetate to create alpha-ketoglutarate and processed by the TCA cycle

b. in the absence of insulin there is a depletion of oxaloacetate and accumulation of Acetyl-CoA

c. Acetyl-CoA can feed into the formation of ketone bodies and excess ketone body production can lower blood pH in Habetics.

d. i and ii

e. ii and iii

f. i and iii

g. All of the above

h. None of the above

e. ii and iii

Which of the following is NOT true about fatty acid synthesis?

a. The coenzyme for the oxidation and reduction reactions is NADP+/NADPH b. Intermediates are linked to acyl carrier proteins. Fatty acid synthesis occurs in the mitochondria

c. Fatty acid synthesis occurs in the mitochondria. The coenzyme for the oxidation and reduction reaction is NADP+/NADPH

d. Fatty acid synthesis occurs in the mitochondria

e. Intermediates are linked to acyl carrier proteins

d. Fatty acid synthesis occurs in the mitochondria

What is the role of biotin in the beta-oxidation of ODD-Carbon fatty acids?

a. Biotin adds CoA to odd-carbon acyl chain

b. Biotin removes phosphate from ATP to form carboxyphosphate

c. Biotin takes part in the addition of a CO2 to Propionyl-CoA

d. Biotin removes the terminal carbon to make an even-carbon chain

e. Biotin removes CO2 from the odd-carbon chain

c. Biotin takes part in the addition of a CO2 to Propionyl-CoA

.Humans cannot achieve NET glucose synthesis from C-even fatty acids due to the inability to convert

a. Acetyl-CoA to malonyl CoA

b. Acetyl-CoA to acetoacetate

c. Acetyl-CoA to pyruvate

d. Methylmalonyl-CoA to succinyl-CoA

e. Oxaloacetate to pyruvate

c. Acetyl-CoA to pyruvate

Coenzyme A and acyl carrier protein (ACP) resemble one another since both a. Carry fatty acids across the mitochondrial membrane

b. Contain biotin

c. Contain lipoic acid

d. Contain 4'-phosphopantetheine

e. None of these

d. Contain 4'-phosphopantetheine

Beta-oxidation of fatty acids with even number of carbons will produce all of the following except:

a. Butyryl-CoA

b. NADH

c. FADH2

d. Malonyl-CoA

e. Acetyl-CoA

a. Butyryl-CoA

The end product of glycolysis is pyruvate. However, pyruvate cannot directly enter the TCA cycle. What needs to happen to pyruvate for the TCA cycle to proceed

a. Pyruvate must lose a CO2 when it reacts with TPP and form hydroxyethyl-TPP

b. The acetyl group linked to TPP must be transferred to lipoamide

c. Pyruvate must lose a CO2 when it reacts with TPP and form hydroxyethyl-TPP, CoA-SH acquires an acetyl group to make acetyl-CoA

d. CoA-SH acquires an acetyl group to make Acetyl-CoA

e. Pyruvate must lose a CO2 when it reacts with TPP and forms hydroxyethyl-TPP. The acetyl group linked to TPP must be transferred to lipoamide. CoA-SH acquires an acetyl group to make Acetyl-CoA

e. Pyruvate must lose a CO2 when it reacts with TPP and forms hydroxyethyl-TPP. The acetyl group linked to TPP must be transferred to lipoamide. CoA-SH acquires an acetyl group to make Acetyl-CoA

The fate of acetate, the product of ethanol metabolism, is which of the following?

a. It is toxic to the tissues of the body can lead to hepatic neurosis

b. It enters the TCA cycle directly to be oxidized

c. It is excreted in bile

d. It is raked up by other tissues and activated to acetyl-CoA

e. It is converted to NADH by ADH enzyme

d. It is raked up by other tissues and activated to acetyl-CoA

.Which of the following would be expected to occur after alcohol ingestion? a. The activation of fatty acid oxidation

b. An increase in gluconeogenesis

c. The inhibition of ketogenesis

d. A decrease in NAD/NADH+ ratio

e. Lactic acidosis

e. Lactic acidosis

Anaplerotic pathways are critical for re-supplying 4-carbon intermediates to the TCA cycle to compensate for their removal by pathways such as gluconeogenesis. Which of the following comprise important anaplerotic reactions in the liver?

a. Conversion of alanine to alpha-ketoglutarate via transamination

b. Production of ketone bodies (acetoacetate beta-hydroxybutyrate)

c. Conversion of alpha-ketoglutarate to glutamate and GABA via glutamate dehydrogenase

d. Conversion of pyruvate to oxaloacetate via pyruvate carboxylase, biotin, bicarbonate ion and ATP

e. Conversion of phosphoenolpyruvate to pyruvate by phosphoenolpyruvate carboxykinase (PEPCK)

d. Conversion of pyruvate to oxaloacetate via pyruvate carboxylase, biotin, bicarbonate ion and ATP

Which statement is incorrect about insulin?

a. Insulin is a polypeptide hormone consisting of two disulfide linked chains

b. Insulin is secreted by beta cells of pancreatic islets in response to high blood glucose and amino acid levels

c. Insulin promotes synthesis of glycogen, triacylglycerols, and proteins

d. Insulin receptors in target tissues act through cAMP to promote protein phosphorylation

e. One of the actions of insulin is to increase the number of glucose transporters on the surface of adipose and muscle cells

d. Insulin receptors in target tissues act through cAMP to promote protein phosphorylation

Although skeletal muscle is replete with glycogen that glycogen cannot be used to increase blood glucose levels because of the lack of which enzyme

a. Pyruvate carboxylase

b. PEP carboxykinase

c. Glyceraldehyde phosphate dehydrogenase

d. Phosphorylase

e. Glucose 6 phosphatase

e. Glucose 6 phosphatase

The final product in the breakdown of glycogen is

a. UDP-glucose

b. Glucose-1-phosphae

c. Glycogenin

d. Glucose

e. Glucose-6-phosphate

d. Glucose

High levels of ATP and citrate:

a. Indicate a high energy-well fed state.

b. Inhibit glycolysis

c. Indicate remote gluconeogenesis

d. All of the above

e. None of the above

d. All of the above

.Which of the following would be associated with LOW pyruvate dehydrogenase rate?

a. Low ATP

b. High ADP

c. Low NADH

d. High NADH/Low NAD+

e. Low Acetyl-CoA

d. High NADH/Low NAD+

The hallmarks of acute alcoholism without food intake are acidosis and hypoglycemia. These metabolic changes are due to the:

a. An increase in the use of the glycolytic pathway. The use of glycolysis rather than the electron transport chain to produce ATP would result in a deficiency of energy in the liver cell.

b. Metabolism of ethanol, which prevents the production of sufficient levels of blood glucose from lactate, glycerol and alanine.

c. Metabolism of ethanol, which prevents the production of sufficient levels of blood glucose from glycogen stores.

d. Lack of food uptake (glucose) and the cellular metabolism of alcohol generates high concentration of NADPH, which is favorable for ketoacids production.

e. Increase of consumption of alcohol leads to acute inflammation of the liver, which leads to massive consumption of glucose-6-phosphate as an energy source and hypoglycemia in the serum

b. Metabolism of ethanol, which prevents the production of sufficient levels of blood glucose from lactate, glycerol and alanine.

Hormonal activation of cyclic AMP levels will:

a. Lead to the activation of PFK.

b. activate protein kinase A phosphorylation of Fructose bisphosphatase 2.

c. Phosphorylate PFK2 on a tyrosine residue.

d. Increase the activation of gluconeogenesis

e. Activate the PKC phosphorylation of PFK2

d. Increase the activation of gluconeogenesis

Activate the PKC phosphorylation of PFK2. 5. Which of the following vitamins are precursors to coenzymes that are necessary for the formation of acetyl CoA from pyruvate?

a. Thiamine, riboflavin, niacin, and biotin

b. Thiamine, riboflavin, niacin, lipoic acid, and pantothenic acid

c. Thiamine, riboflavin, and lipoic acid

d. Thiamine, riboflavin, niacin, lipoic acid, pantothenic acid, and biotin

e. None of the above

d. Thiamine, riboflavin, niacin, lipoic acid, pantothenic acid, and biotin

In addition to pyruvate dehydrogenase, what other enzyme(s) in the citric acid cycle has a key thiamine pyrophosphate coenzyme?

a. α-ketoglutarate dehydrogenase

b. Aconitase

c. Citrate synthase

d. Malate dehydrogenase

e. Isocitrate dehydrogenase

a. α-ketoglutarate dehydrogenase

Why does acetyl CoA, a product of fatty acid catabolism, influence the pyruvate dehydrogenase complex (PDH), a control point in carbohydrate catabolism?

a. When fatty acid breakdown is inhibited, ADP is low, causing a decrease in activity

b. When fatty acid breakdown is inhibited, PDH is inhibited by acetyl CoA due to phosphatase activity.

c. When fatty acid breakdown is high, NADH levels drop, causing an increase in E2 activity.

d. When fatty acid breakdown is high, ADP is low and PDH is inhibited by phosphatase activity.

e. When fatty acid breakdown is high, PDH is inhibited by acetyl CoA due to pyruvate kinase activity.

e. When fatty acid breakdown is high, PDH is inhibited by acetyl CoA due to pyruvate kinase activity.

The citric acid cycle is activated in the presence of oxygen (O2), but what is the link between the citric acid cycle and O2?

a. O2 is an allosteric activator for citrate synthase

b. The iron-sulfur center requires O2 to be in the appropriate oxidation state

c. The presence of O2 in the mitochondrial matrix releases CO2 into the cytosol.

d. The one substrate-level phosphorylation in the citric acid cycle can occur in the absence of O2

e. A primary product of the citric acid cycle is NADH, the principle electron donor to the O2, the last electron acceptor in the electron-transport system.

e. A primary product of the citric acid cycle is NADH, the principle electron donor to the O2, the last electron acceptor in the electron-transport system.

What is(are) the chemical change(s) involved in the conversion of citrate into isocitrate?

a. Dehydration followed by hydration

b. Oxidation followed by reduction

c. Oxidation

d. Oxidative decarboxylation

e. Hydration followed by dehydration

a. Dehydration followed by hydration

Which of the following conditions will activate pyruvate dehydrogenase kinase, which catalyzes the phosphorylation and inactivation of E1 in the pyruvate dehydrogenase complex?

a. Insulin

b. Elevated concentrations of NAD+ and ADP

c. Ca2+

d. Elevated concentrations of NADH and ATP

e. Elevated concentrations of acetyl CoA

d. Elevated concentrations of NADH and ATP