Exam 2 Questions Flashcards by Carl Gonzales

When glucagon binds to cell surface receptors, which of the following response is unlikely?

Skeletal muscle: glycogen breakdown will be stimulated

Hepatocytes: gluconeogenesis will be accelerated

Adipocytes: fatty acid synthesis will be stimulated

Hepatocytes: glycogen breakdown will be stimulated

Adipocytes: fatty acid release will be stimulated

Adipocytes: fatty acid synthesis will be stimulated

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For catabolism of the amino acids with hydroxyl groups, the amino groups are usually removed by:

Oxidative deamination

Hydrolysis to remove a-amino group

Dehydration initiated deamination

Transamination to remove a-amino group

Decarboxylation initiated deamination

Dehydration initiated deamination

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Which statement is INCORRECT regarding the transport of long-chained fatty acids into the mitochondrial matrix?

It is not a rate-limiting step in the oxidation of these fatty acids.

The cytosolic and mitochondrial matrix pools of coenzyme A are separated by biomembranes

Once these fatty acyl molecules are in the matrix, carnitine can be transported out of mitochondria.

It is inhibited by the increase of malonyl-CoA levels

Patients with a carnitine deficiency are likely to have impaired beta-oxidation of fatty acids

It is not a rate-limiting step in the oxidation of these fatty acids.

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In gluconeogenesis, how many moles of ATP are required to synthesize one mole glucose from 2 moles of PEP?

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In a lipogenic liver, the beta oxidation pathway is repressed mainly by:

Lack of ATP, fatty acids cannot be activated

Increase of Ca++ in mitochondrial matrix, which speed up TCA cycle and increased ATP inhibits beta-oxidation

Increased glucagon level, thus promoting the utilization of glucose, repressing utilization of fatty acids

Increased level of malonyl CoA, which represses Carnitine-acyl CoA transferase I activity, thus slowing down the translocation of acyl-CoA to mitochondria

Lipogenesis depletes ATP, which activates AMPK and inhibits energy consumption, so cell does not need a fast beta oxidation

Increased level of malonyl CoA, which represses Carnitine-acyl CoA transferase I activity, thus slowing down the translocation of acyl-CoA to mitochondria

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Insulin stimulates PI3K-PKB pathway, which uses a cascade of phosphorylation events to amplify the signal, and eventually may lead to:

Increasing internalized Glut4

Converting glycogen phosphorylase a to phosphorylase b

Converting phosphorylated glucose to glucose

Converting glycogen phosphorylase b to phosphorylase a

Converting glycogen synthase a to glycogen synthase b

Converting glycogen phosphorylase a to phosphorylase b

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Which of the following statements about lipid digestion and absorption is NOT correct?

Absorbed lipids will be incorporated into chylomicrons, which is released by intestinal mucosa

Chylomicron carries a protein called Apo protein B100 on its surface

Malabsorption causes lack of essential fatty acids and lipid soluble vitamins

Digestion needs lipases secreted by pancreas and bile juice from gallbladder

Chylomicrons will be transported to the circulation via lymph duct

Chylomicron carries a protein called Apo protein B100 on its surface

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Unlike skeletal muscle, cardiac muscle metabolism is highly oxygen-dependent.

True

False

True

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Completely oxidation of one mole of hexanoyl CoA (an 6C, fully saturated fatty acyl Co) in mitochondrion maximally may generate:

30 mole ATP

32 mole ATP

38 mole ATP

48 mole ATP

42 mole ATP

38 mole ATP

((Even # / 2) – 1) * 4 ATP = # of total ATP from beta oxidation rounds

(Even # /2) * 10 ATP = # of total ATP from ETC

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Historically, which term was used to indicate the glycolytic processes in normal eukaryotic cells?

The Warburg Effect

The Embden-Meyerhof-Parnas (EMP Pathway)

The Krebs Effect

The Pasteur Effect

The Embden-Meyerhof-Parnas (EMP Pathway)

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In humans. the Cori cycle is an example of metabolic coordination among active skeletal muscle. the circulatory system and liver. Which two metabolic pathways are involved in this cycle?

Glycolysis in muscle and the pentose phosphate pathway in liver

Gluconeogenesis in muscle and glycogenolysis in liver

Glycolysis in muscle and gluconeogenesis in liver

Beta-oxidation in muscle and ketogenesis in liver

Pentose phosphate pathway in muscle and gluconeogenesis in liver

Glycolysis in muscle and gluconeogenesis in liver

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During starvation, AMP increase in hepatocytes indicates ATP depletion which stimulates AMPK activity. A well-known activity of AMPK is to phosphorylate acetyl-CoA carboxylase (ACC). This phosphorylation will:

Inhibit TCA

Stimulate ACC activity

Increase fatty acid synthesis

Block glycolysis

Decrease fatty acid synthesis

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Deficiency of fatty acyl-CoA dehydrogenase may lead to:

Stearate diarrhea

Vitamin D insufficiency

Infant diabetes

Infant sudden death

Malabsorption of essential fatty acids

Infant sudden death

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General effects of glucagon on skeletal muscle include:

Glycolysis increases

Glycogen synthase activity increases

Glycated myoglobin increases

Glycogen breakdown increases

Glycogen synthesis is stimulated

Glycogen breakdown increases

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The most important rate limiting enzyme for glycolysis is

Phosphofructose kinase 1 (PFK1)

Glyceraldehyde-3 phosphate dehydrogenase

Pyruvate kinase

Phosphoglycerate kinase

Hexokinases

Phosphofructose kinase 1(PFK1)

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About ketone bodies, which of the following statement is not correct?

Can be used by all tissues including neurons and hepatocytes

Overproduction of ketone bodies may occur in diabetic patients, even with hyperglycemia

Are produced by hepatocytes

Are produced from acetyl-CoA

Is an alternative fuel, particularly important for brain

Can be used by all tissues including neurons and hepatocytes

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The mobilization and utilization of endogenous TAG may not include:

Insulin signaling activates hormone sensitive lipase on white adipose tissue (adipocytes), which releases fatty acids

Transport free fatty acids by the circulatory system to cells which need fatty acids as fuel

ATP-dependent activation of free fatty acid to form acyl-CoA in the cytosol

Beta-oxidation, resulting in cleavage by thiolase to form acetyl-CoA in mitochondrion

Translocation of acyl-CoA into mitochondria, a caritine-dependent process

Insulin signaling activates hormone sensitive lipase on white adipose tissue (adipocytes), which releases fatty acids

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The following molecules are involved in fatty acid biosynthesis, except for:

Malic enzyme

Pyruvate carboxylase

Acetyl-CoA carboxylase

Malonyl-CoA

Fatty acid synthase (FAS)

Pyruvate carboxylase

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The major pathway responsible for maintaining blood glucose level 48 hours after a regular meal is:

Glycogenesis

Glycolysis

Pentose phosphate pathway, non-oxidative phase

Glycogenolysis

Gluconeogenesis

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Human fatty acid synthase is an enzyme complex of multiple subunits, each with a specialized enzyme activity.

True

False

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PLP is a cofactor required for glycogen phosphorylase activity, which is derived from vitamin B6

True

False

True

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The rate of pentose phosphate pathway is limited by G6PD activity, which is allosterically inhibited by:

Decrease of mitochondrial NADPH levels

Increase of intracellular NADPH levels

Decrease of intracellular NADPH levels

Decrease of ribose phosphate levels

Increase of ribose-phosphate levels

Increase of intracellular NADPH levels

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Pentose phosphate pathway has two phases: the oxidative phase and the non-oxidative phase.

True

False

True

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Under anaerobic conditions, yeast performs two additional steps after glycolysis; which convert pyruvate to ethanol. What is the purpose served by these two additional steps in the metabolism of yeast cells?

They are required to complete the oxidation of glucose and maximizing ATP production

They are required to remove pyruvate, ensuring ATP production

They know our students like beer

They are required to re-oxidize limited amounts of NADH to NAD+ and decrease pyruvate level, thus sustaining continuous glycolysis to ensure ATP production

They are required to oxidize NADH to generate ATP

They are required to complete the oxidation of glucose and maximizing ATP production

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Under anaerobic condition, one of the products of the glycolysis, pyruvate, is converted to lactate. The biological importance of this reaction is: Lactate can reduce the intracellular pH, which helps the cell survival To oxidize NADH to NAD+, a required cofactor for glycolysis; so ATP production via glycolysis can continue To increase lactate levels in cells in order to enhance the expression of lactate dehydrogenase. This process is directly coupled with substrate level phosphorylation, hence making ATP Without oxygen, neurons use lactate as a fuel supply

To oxidize NADH to NAD+, a required cofactor for glycolysis; so ATP production via glycolysis can continue

The rate limiting step in fatty acid biosynthesis is: The final step, release of palmitate from FAS Acetyl CoA carboxylation by ACC to form malonyl COA Malonyl CoA association with fatty acid synthase (FAS) Dehydrogenation of malate in the cytosol by malic enzyme Citrate break down by citrate lyase to form acetyl CoA and OAA in the cytosol

Acetyl CoA carboxylation by ACC to form malonyl COA

G6P phosphatase is an enzyme specifically expressed in hepatocytes True False

True

Which of the following carbon sources cannot be used in gluconeogenesis in human cells? Succinyl-CoA Aspartate Palmitate Alanine Glutamate

Palmitate

Basal level of metabolism is regulated by thyroids T3/T4 True False

True

The catabolism of odd-numbered fatty acids and some amino acids generate a metabolite propionyl-CoA. Further catabolism of propionyl-CoA requires the following vitamins, except for: Vitamin B1 Vitamin B3 Vitamin B2 Vitamin B7 Vitamin B12

Vitamin B1

After entering cells, the immediate product of the first reaction catalyzed by hexokinase is Glucose 1-phosphate Fructose 6-phosphate Fructose 1-phosphate Glucose 6-phosphate Glucose 3-phosphate

Glucose 6-phosphate

About AMPK, which one of the following statements is incorrect? It is a protein kinase activated by increased level of AMP in cells It is a molecule binds and synergizes with insulin to promote glycolysis in multiple tissues Exercise may activate its activity in myocytes (muscle cells) It synergizes with insulin, and represses the expression of PEPCK in hepatocyte It is an intracellular energy sensor regulating the energy metabolism at the cellular level

It is a molecule binds and synergizes with insulin to promote glycolysis in multiple tissues

Ketone bodies can be utilized by the following organs, except for: Brain Liver Heart Kidney Skeletal muscle

Liver

About gluocorticoids, which of the following statements is INCORRECT? A hormone binding to cell surface receptor to synergize epinephrine effect A hormone made and released by cortex of adrenal gland It binds to its nuclear receptor and regulate gene expression It is involved in organismal level response to chronic stress by increase blood glucose levels it is suppressive to immune response and allergic reaction

A hormone binding to cell surface receptor to synergize epinephrine effect

The oxidized glutathione protects enzymes from oxidative damage True False

False

Ref. Fig attached. The one used directly in the initiation of biosynthesis of phosphatidic acid is: a b c d e

In figure attached, glyceraldehyde-3 phosphate is: a b c d e

In which compartment of cell does fatty acid synthesis occur? Nucleus Mitochondrion Soluble cytoplasm (cytosol) Golgi complex Endoplasmic reticulum (ER)

Soluble cytoplasm (cytosol)

Generally, the effects of epinephrine (adrenaline) on hepatocytes may include: Inhibiting glycolysis Enhancing glycogen synthase activity Inhibiting glycogenolysis Stimulating glycogen synthesis Inhibiting glycogen breakdown

Inhibiting glycolysis

About glycogenin expression and subcellular localization the right combination is: Hepatocyte; cytosol Adipocyte; mitochondrion Myocyte; mitochondrion Myocyte; endoplasmic reticulum Cardiac myocyte; peroxisome

Hepatocyte; cytosol

Which of the following enzymes has the least influence on the speed of glycolytic pathway? Hexose kinase Phosphofructose kinase 2 Phosphofructose kinase 1 Pyruvate kinase Phosphoglycerate mutase

Phosphoglycerate mutase

The pyruvate dehydrogenase complex is mainly located: In the cytosol On the mitochondrial inner membrane In the smooth ER In the mitochondrial matrix In the peroxisome

In the mitochondrial matrix

Some steps in the glycolytic pathway cannot be simply reversed in gluconeogenesis, thus need bypassing by different enzymes; these steps include the following, except for: F1,6BP broken by aldolase Phosphoenolpyruvate to pyruvate, accompanied by substrate level phosphorylation Pyruvate kinase-catalyzed formation of pyruvate Hexokinase-catalyzed formation of G6P PFK1-catalyzed formation of F1,6BP

F1,6BP broken by aldolase

In figure attached, Dihydroxylacetone phosphate (DHAP) is: a b c d e

Pyruvate dehydrogenase complexes uses several cofactors which require the following vitamins as precursor, except for: Vitamin B2 Vitamin B3 Vitamin B5 Vitamin B6 Vitamin B1

Vitamin B6

In pentose phosphate pathway, after two steps of oxidation, the end products from one molecule of G6P will be: Two NADPH and one pentose phosphate One NADH, one NADPH and one ribose phosphate One NADPH and one pentose phosphate Two NADH and one pentose phosphate Two NADPH and two pentose phosphate

Two NADPH and one pentose phosphate

Glycogen storage disease may be caused by the deficiency of the following enzymes, except for: Glyceraldehyde-P dehydrogenase Glycogen synthase Glycogen phosphorylase Branching enzyme Lysosomal glycosidase

Glyceraldehyde-P dehydrogenase

Which of the following correctly describes the sequence of events of beta-oxidation of fatty acyl-CoA in mitochondria? Dehydrogenation-hydration-dehydrogenation-cleavage Hydration-dehydrogenation-dehydrogenation-cleavage Dehydrogenation-hydration-dehydration-cleavage Dehydrogenation-dehydrogenation-hydration-cleavage Dehydrogenation-dehydration-dehydrogenation-cleave

Dehydrogenation-hydration-dehydrogenation-cleavage

After an Italian spaghetti meal an increase of blood glucose levels to 12 mM will significantly increase the activity of: Glut3 Glut1 Glut1, Glut2, and Glut3 Glut1 and Glut3 Glut2

Glut2

Which process is NOT considered a general function of the pentose phosphate pathway? The transfer of electrons to the electron transport chain for ATP production The production of pentoses necessary for nucleotide synthesis The production of pentose phosphate for biosynthesis of some cofactors The production of NADPH to help prevent oxidative stress in erythrocytes The production of NADPH for reductive biosynthesis in adipose cells

The transfer of electrons to the electron transport chain for ATP production

About insulin, which of the following statement is NOT correct? Its target organs/tissues include liver, muscle and adipose It is produced by pancreatic beta cells Its release is triggered by increased ATP levels in beta cells It promotes glycogen phosphorolysis and glycolysis to generate large amount of ATP in muscle It may regulate the expression of metabolic enzymes

It promotes glycogen phosphorolysis and glycolysis o generate large amount of ATP in muscle

When some amino acids are utilized as carbon sources, removing the alpha amino group by transamination with alpha-KG requires a cofactor derived from- Vitamin B6 Vitamin B5 Vitamin B3 Vitamin B7 Vitamin B1

Vitamin B6

Which of the following carbon sources cannot be used in gluconeogenesis? Glycerol-3 phosphate released from breakdown of phospholipids Acetyl CoA from beta oxidation Alpha-ketoglutarate from glutamate and glutamine catabolism OAA from aspartate catabolism Riboses from pentose pathway

Acetyl CoA from beta oxidation

In some cell types, insulin signaling will trigger the glucose transporter 4 translocating to the cell membrane, hence increasing the transport of glucose into cells. Which cell types respond to insulin in this manner? Erythrocytes and neurons Erythrocytes and adipocytes Hepatocytes and skeletal myocytes Skeletal myocytes and adipocytes Neurons and the hepatocytes

Skeletal myocytes and adipocytes

For fatty acid biosynthesis, each round contains four reactions. Which of the following accurately describes the four reactions in the correct order? Condensation-reduction-dehydration-reduction Condensation-reduction-dehydrogenation-reduction Condensation-dehydrogenation-reduction, reduction Condensation-reduction-hydration-reduction Dehydrogenation, condensation, dehydration, reduction

Condensation-reduction-dehydration-reduction

When adipose tissue increases, the hormone leptin released to circulation also increases, which may regulate feeding behavior by Stimulating the arcuate neurons to release both a-MSH and NPY Stimulating the arcuate neurons to release a-MSH but suppressing the release of NPY by other neurons Stimulating the arculate neurons to release a-MSH only, no effect on NPY release Inhibiting the release of both a-MSH and NPY Stimulating the arculate neurons to release NPY, no effect on a-MSH

Stimulating the arcuate neurons to release a-MSH but suppressing the release of NPY by other neurons

Fructose-2,6-bisphosphate is: An intermediate metabolite in fatty acid synthesis A waste byproduct of the glycolytic pathway An intermediate product of catabolism of fructose to generate ATP An intermediate product of glycolysis which promote the release of O2 A regulatory molecule that allosterically stimulates PFK1 activity and the glycolytic pathway

A regulatory molecule that allosterically stimulates PFK1 activity and the glycolytic pathway

At 50 hours after a regular meal, in addition to glucose, another major carbon fuel supplied by liver to neurons is: Amino acids Ketone bodies Fructose Acetyl-CoA Fatty acids

Ketone bodies

In humans, the Cori cycle is an example of metabolic coordination among the active skeletal muscle, the circulatory system and the liver. Which two metabolic pathways are involved in this cycle? Pentose phosphate pathway in muscle to generate NADPH and gluconeogenesis in liver to provide glucose Glycolysis in muscle to generate ATP and the pentose phosphate pathway in liver to supply NADPH Glycolysis in muscle to make ATP and gluconeogenesis in liver to supply glucose Gluconeogenesis in muscle to increase G6P, and glycogenolysis in liver to supply more glucose to muscle Beta-oxidation in muscle to generate ATP and ketogenesis in liver to supply muscle more fuel

Glycolysis in muscle to make ATP and gluconeogenesis in liver to supply glucose

Insulin stimulates protein kinase B (PKB) pathway, which uses a cascade of phosphorylation events to amplify the signal, and eventually may lead to: Converting glycogen phosphorylase a to glycogen phosphorylase b Converting phosphorylated glucose to glucose increasing internalized Glut4 Converting glycogen phosphorylase b to phosphorylase a Converting glycogen synthase a to glycogen synthase b

Converting glycogen phosphorylase a to glycogen phosphorylase b

About glucocorticoids. which of the following statements is INCORRECT? A hormone made and released by cortex of adrenal gland It is involved in organismal level response to chronic stress by increasing blood glucose levels A hormone binding to cell surface receptor to synergize epinephrine effect It binds to its nuclear receptor and regulates gene expression It is suppressive to immune system, and long-term use of medicine with similar biological effects may lead to lipid redistribution and increase infection risk

A hormone binding to cell surface receptor to synergize epinephrine effect

In which cellular compartment does fatty acid synthesis occur? Endoplasmic reticulum (ER) where NADPH level is high Mitochondrion where NADH level is high Nucleus where NADPH level is high Golgi complex where NADPH level is high Soluble cytoplasm (cytosol) where NADPH level is high

Soluble cytoplasm (cytosol) where NADPH level is high

About AMPK, which one of the following statements is incorrect? It is a protein kinase activated by increased level of AMP in cells Exercise activates its activity in myocytes (muscle cells) Adiponectin, a hormone released by adipose tissue, activates it in multiple tissues It is an intracellular energy sensor regulating the energy metabolism at the cellular level It is a circulating molecule binds with insulin to promote glycolysis in multiple tissues

It is a circulating molecule binds with insulin to promote glycolysis in multiple tissues

Each round of beta-oxidation has 4 steps. The correct order of the four steps are: Dehydrogenation to generate FADH2, dehydration to form hydroxyl group, dehydrogenation to generate NADH and carbonyl group, cleavage to form an acetvi=CoA and a new acyl-CoA Dehydrogenation to generate FADH2, Hydration, dehydrogenation to generate NADH, cleavage to form an acetyl CoA and a new acyl-CoA Dehydrogenation to generate NADH, hydration to form a hydroxyl group, dehydrogenation to generate FADH2 and carbonyl group, cleavage to form an acetyl-CoA and a new acyl-CoA. Dehydrogenation to generate FADH2, dehydrogenation to generate NADH, hydration to form alcohol, dehydration to generate carbonyl group, cleavage to form an acetyl=CoA and a new acyl-CoA. Dehydrogenation to generate FADH2, reduction to hydroxyl group, dehydrogenation to generate NADH and carbonyl group, cleavage to form an acetyl-CoA and a new acyl-CoA

Dehydrogenation to generate FADH2, Hydration, dehydrogenation to generate NADH, cleavage to form an acetyl CoA and a new acyl-CoA

GIvcogen Storage Diseases may be caused by a defect of: Glycogen synthase Muscle PFK1 Lysosomal glucosidase A and B A, B, and C

A, B, and C

In a lipogenic liver, the most important enzyme to carry out anaplerotic reaction is: Acetyl-CoA carboxylase (ACC) Pyruvate carboxylase (PC) Malonyl CoA-decarboxvlase transaminase PEP carboxykinase (PEPCK)

Pyruvate carboxylase (PC)

Which of the following carbon sources cannot be used in gluconeogenesis in human cells? Proline Threonine Palmitate Glutamate Aspartate

Palmitate

The rate of pentose phosphate pathway is limited by G6PD activity, which is allosterically inhibited by: Decrease of intracellular NADPH levels Increase of intracellular NADPH levels Decrease of ribose phosphate levels Increase of ribose-phosphate levels Decrease of mitochondrial NADPH levels

Increase of intracellular NADPH levels

Basal level of metabolic rate is mainly regulated by thyroid T3 True False

True

The rate limiting step in fatty acid biosynthesis is: Citrate break down by citrate lyase to form acetyl-CoA and OAA in the cytosol Dehydrogenation of malate in the cytosol by malic enzyme The final step, release of palmitate from FAS-I Malonyl-CoA association with ACP of fatty acid synthase (FAS) Acetyl CoA carboxylation by ACC to form malonyl-CoA

Acetyl CoA carboxylation by ACC to form malonyl-CoA

During starvation, AMP increase in hepatocytes stimulates AMPK activity. A well-known activity of AMPK is to phosphorylate acetyl-CoA carboxylase (ACC). Based on the above facts and the principles we discussed in lectures, one can deduce that this phosphorylation will: Decrease malonyl-CoA level thus stimulating beta-oxidation Increase malonyl-CoA thus stimulating beta-oxidation Inhibit ACC and decrease fatty acid synthesis Stimulate ACC and increase fatty acid synthesis Inhibit ACC, lower malonyl-CoA levels, thus inhibiting fatty acid synthesis but stimulating beta-oxidation

Inhibit ACC, lower malonyl-CoA levels, thus inhibiting fatty acid synthesis but stimulating beta-oxidation

The major pathway responsible for maintaining blood glucose level 38 hours after a regular meal is: Pentose phosphate pathway, non-oxidative phase Glycogenolysis Glycation Glycogenesis Gluconeogenesis

Gluconeogenesis

About ketone bodies. which of the following statement is incorrect? Is an alternative fuel during starvation for all cells, but is particularly important for brain Are produced by hepatocytes Can be used by all types of cells as alternative fuel including neurons and hepatocytes Are produced from acetyl-CoA Is made in the mitochondria

Can be used by all types of cells as alternative fuel including neurons and hepatocytes

About insulin, which of the following statement is incorrect? It promotes both glycogen phosphorolysis and glycolysis to generate large amount of ATP in targeted tissues Its target organs/tissues mainly include liver, muscle and adipose It may regulate the expression level of some metabolic enzymes as well. Its release pancreatic beta cells is triggered by increased ATP levels Its release by pancreatic beta cells is triggered by increased cytosolic calcium ions

It promotes both glycogen phosphorolysis and glycolysis to generate large amount of ATP in targeted tissues

For fatty acid biosynthesis. each round contains four reactions. Which of the following accurately describes the four reactions in the correct order? Dehydrogenation, condensation, dehydration, reduction Condensation-dehydrogenation-reduction, reduction Condensation-reduction-hydration-reduction Condensation-reduction-dehydration-reduction Condensation-reduction-dehydrogenation-reduction

Condensation-reduction-dehydration-reduction

Ketone bodies can be utilized by the following organs, except for: Brain Heart Skeletal muscle Kidney Liver

Liver

During acute stress response, the adrenal gland releases epinephrine to circulation, which stimulates heart beat and respiration. Per logics we discussed, we can deduce that the effects of epinephrine (adrenaline) on hepatocytes may include: Enhancing fatty acids synthase activity Stimulating glycogen synthesis Inhibiting glucogenolysis Inhibiting glycogen breakdown Inhibiting glycolysis

Inhibiting glycolysis

During active fatty acid synthesis. the beta oxidation pathway is usually repressed. This is achieved mainly by: Lack of ATP, fatty acids cannot be activated to form fatty acyl-CoA Lipogenesis depletes ATP, which activates AMPK and inhibits energy consumption, beta oxidation function is inhibited Increase of Ca++ in mitochondrial matrix. which speeds up TCA cycle and increased ATP level that in turn inhibits beta-oxidation Increased level of malonyl-CoA, which represses Carnitine-acyl-CoA transferase I (CAT-1) activity, thus slowing down the translocation of acyl-CoA to mitochondria Increased glucagon level, thus promoting the utilization of glucose, repressing utilization of fatty acids

Increased level of malonyl-CoA, which represses Carnitine-acyl-CoA transferase I (CAT-1) activity, thus slowing down the translocation of acyl-CoA to mitochondria

During fatty acid synthesis in a lipogenic liver, the major sources of acetyl CoA is: Acetyl CoA directly exported from mitochondria Malonyl-CoA, decarboxylated in cytosol Ketone body released by mitochondria Pyruvate from glycolysis, dehydrogenated in cytosol Citrate exported from mitochondria, cleaved by ATP citrate lyase (ACL)

Citrate exported from mitochondria, cleaved by ATP citrate lyase (ACL)

Some steps in the glycolytic pathway cannot be simply reversed in gluconeogenesis, thus need bypassing by different enzymes in gluconeogenesis; these steps include the follwoing, except for: F1,6BP broken to form DHAP & GAP by aldolase PFK1-catalyzed formation of F1,6BP Phosphoenolpyruvate to pyruvate, accompanied by substrate level phosphorylation Hexokinase-catalyzed formation of G6P Pyruvate kinase-catalyzed formation of pyruvate

F1,6BP broken to form DHAP & GAP by aldolase

When glucagon binds to cell surface receptors, which of the following response is unlikely? Skeletal muscle: glycogen breakdown will be stimulated Adipocytes: fatty acid release will be stimulated Hepatocytes: glycogen breakdown will be stimulated Adipocytes: fatty acid synthesis will be stimulated Hepatocytes: gluconeogenesis will be accelerated

Adipocytes: fatty acid synthesis will be stimulated

About fatty acids synthesis in hepatocytes. which of the following statement is incorrect? It is catalyzed by FAS-I All required enzymatic activities are included in a single protein At the initial step, the first acetyl CoA also accesses the FAS-I by ACP It needs eight rounds to make a palmitate and six rounds to make a laurate ACP is the only site for malonyl-CoA to interact with FAS-I

It needs eight rounds to make a palmitate and six rounds to make a laurate #of cycles = (#C/2)-1 Ex: palmitate is 16 => 7 cycles

After uptaking into cardiomyocyte, an 18C-fatty acid will likely be utilized to make ATP in the following order: Activated by ATP in cytosol to fatty acyl-CoA, beta-oxidation to generate Acetyl CoA, then Acetyl CoA is transported into mitochondrion via acyl-carnitine/carnitine Activated by carnitine directly in cytosol, transported into mitochondrion via acyl-carnitine/carnitine transporter, converted to fatty acyl-CoA, beta-oxidation to generate Acetyl-CoA Transported into mitochondrion by facilitated diffusion, activated by ATP to fatty acyl-CoA, beta-oxidation to generate Acetyl-CoA Synthesized into fatty acyl-CoA, transported into mitochondrion via fatty acyl-CoA transporter, activated by ATP, beta-oxidation to generate Acetyl CoA Activated by ATP in cytosol to fatty acyl-CoA, converted to fatty acyl canitine, transported into mitochondrion via acyl-carnitine/carnitine transporter, then beta-oxidation to generate acetyl-CoA

Activated by ATP in cytosol to fatty acyl-CoA, converted to fatty acyl canitine, transported into mitochondrion via acyl-carnitine/carnitine transporter, then beta-oxidation to generate acetyl-CoA

Upon starvation or acute stress, the mobilization and utilization of endogenous TAG stored in adipose tissue may not include: Insulin signaling activates hormone sensitive lipase on white adipose tissue (adipocytes), which releases fatty acids Translocation of fatty acyl-CoA into mitochondria, a carnitine-dependent process Beta-oxidation, resulting in cleavage by thiolase to form acetyl-CoA in mitochondrion ATP-dependent activation of free fatty acid to form acyl-CoA in the cytosol Transport free fatty acids by the circulatory system to cells which need fatty acids as fuel

Insulin signaling activates hormone sensitive lipase on white adipose tissue (adipocytes), which releases fatty acids

Upon glucagon signaling stimulation, G6P phosphatase is an enzyme specifically upregulated in hepatocytes and myocytes to facilitate glucose release to circulation flowing glycogenolysis and gluconeogenesis. True False

False

Insulin signaling triggers the glucose transporter 4 (Glut4) translocating to the cell membrane, hence increasing the transport of glucose into cells. Which cell types express significant amount Glut4 and respond to insulin in this manner? Adipocytes Skeletal myocytes and adipocytes Hepatocytes, adipocytes, skeletal myocytes Hepatocytes Skeletal myocytes

Skeletal myocytes and adipocytes

After entering hepatocytes, the initial increase of glucose concentration may significantly stimulate the velocity of: Hexokinase I Hexokinase IV Neither hexokinase I nor hexokinase IV Hexokinase IV, but inhibits hexokinase I Both hexokinase I and hexokinase IV

Hexokinase IV

The pyruvate dehydrogenase complex PDC contains lipoate (lipoic acid). Regarding this cofactor, which of the following statement is incorrect? It is a prosthetic group needed for the E2 activity (transacetylase) of PDC Human cells may synthesize it, so no vitamin precursor is needed to synthesized It carries electrons and diffuses to complex I in ETC It has two thiol groups (dithiol) that facilitate the transfer of electrons and acetyl group at the same time The dithiol groups are subjective to inhibition by poisons targeting thiol groups

It carries electrons and diffuses to complex I in ETC

Lipid droplet in white adipocyte contains lipases on its surface which may be stimulated by some hormones to release fatty acids True False

True

In the cytosol, NADH generated from glycolysis can be used to reduce DHAP to form: Phosphoenolpyruvate Glycerol-3 phosphate Glyceraldehyde-3 phosphate Glycerate-3 phosphate Glyceraldehyde 1-phosphate

Glycerol-3 phosphate

Pyruvate dehydrogenase complexes uses several cofactors which require the following vitamins as precursors, except for: Vitamin B1 Vitamin B3 Vitamin B5 Vitamin B6 Vitamin B2

Vitamin B6

The single most important rate limiting enzyme for glycolysis is PFK1, which is stimulated by: ATP Cytosolic calcium AMP B and C all A, B, and C

B and C

Regarding propionyl-CoA metabolism, which of the following statement is incorrect? Propionyl-CoA (3C) can be converted to Methylmalnyl-CoA (4C) after a carboxylation reaction facilitated by vitamin B7 Propionyl-CoA may arise from catabolism of odd-numbered fatty acids and some amino acids Further converting methylmalonyl-CoA to succinyl-CoA depends on vitamin B12 activity Propionyl-CoA may be used for gluconeogenesis, thus being glucogenic upon starvation Propionyl-CoA is a rare metabolite, which cannot be further catabolized by human cells, thus being disposed by urine

Propionyl-CoA is a rare metabolite, which cannot be further catabolized by human cells, thus being disposed by urine

Unlike skeletal muscle, cardiac muscle metabolism is highly oxygen-dependent and use fatty acids as the major fuel. True False

True

Like enzymes, glucose transportors may have elasticity feature. Base on this feature, the natural and biochemical glucose sensor of cells is: Glut3 Glut1 and Glut3 Glut1, Glut 2, and Glut3 Glut2 Glut1

Glut2

A drug used in management of diabetic conditions biologically inhibits the complex I of ETC. Based on this information, the pharmacological effects may include the following except for: Gluconeogenesis in hepatocytes will be inhibited AMPK will be activated AMP level will be decreased Lipogenesis in the liver will be inhibited Glycolysis will be stimulated

AMP level will be decreased

Completely oxidation of one mole of a myristate (fully saturated) based fatty acyl-CoA in mitochondrion, assuming all electrons obtained are passed to ETC and used to make ATP, maximally may generate: 14 moles ATP 98 moles ATP 70 moles ATP 28 moles ATP 94 moles ATP

94 moles ATP Myristate is 14 C ((Even # / 2) – 1) * 4 ATP = # of total ATP from beta oxidation rounds + (Even # /2) * 10 ATP = # of total ATP from ETC

General effects of glucagon on skeletal muscle include: Glycolysis increases Glycated myoglobin increases G6P oxidation via pentose pathway is stimulated Glycogen breakdown increases Glycogen synthase activity increases

Glycogen breakdown increases

Which of the following statements about lipid digestion and absorption is NOT correct? Chylomicron carries a protein called Apo- B100 on its surface Absorbed lipids will be incorporated into chylomicrons, which is released by intestinal mucosa Digestion needs lipases secreted by pancreas and bile juice from gallbladder Malabsorption causes lack of essential fatty acids and lipid soluble vitamins Chylomicrons will be transported to the circulation via lymphatic duct

Chylomicron carries a protein called Apo- B100 on its surface

About anaerobic glycolysis, which of the following statement is incorrect? In some bacteria, anaerobic glycolysis generates lactate to recover NAD+ In yeast, anaerobic glycolysis generates alcohol to regenerated NAD+. In human cells, anaerobic glycolysis generates alcohol, which later on degraded by alcohol dehydrogenase to acetaldehyde upon reoxygenation. Anaerobic glycolysis to produce ATP by substrate level phosphorylation, a bioenergetic mechanism evolved earlier than oxidative phosphorylation In mammalian cells. anaerobic glycolysis generates lactate but not alcohol.

In human cells, anaerobic glycolysis generates alcohol, which later on degraded by alcohol dehydrogenase to acetaldehyde upon reoxygenation.

The biological importance of glucose supply includes the following, except for: It can be used to generate ATP in oxygen-independent, ETC-independent manner Some cell types use glucose as the major or even exclusive source for ATP production It is the major type of fuel for cardiac muscle to make ATP It is needed in glycosylation, a type of modification of some proteins It serves as the substrate for pentose pathway to generate NADPH and riboses

It is the major type of fuel for cardiac muscle to make ATP

When adipose tissue mass increases, the hormone leptin released to circulation also increases, which may regulate feeding behavior by Stimulating the neurons to release NPY, no effect on alpha-MSH Inhibiting the release of both alpha-MSH and NPY Stimulating neurons to release alpha-MSH only, no effect on NPY release Stimulating neurons to release both alpha-MSH and NPY Stimulating specialized neurons to release alpha-MSH but suppressing the release of NPY by other type of neurons

Stimulating specialized neurons to release alpha-MSH but suppressing the release of NY by other type of neurons

After biosynthesis, palmitate can be further modified by enzyme-dependent elongation and oxidation. These two modifications mainly occur in Cell surface membrane Golgi complex Cytosol Smooth endoplasmic reticulum Mitochondria

Smooth endoplasmic reticulum

Under normal physiological conditions, which of the following statements about nutrient metabolism is INCORRECT? All even-numbered and odd-numbered fatty acids can be catabolized completely Poly-unsaturated fatty acids cannot be catabolized and may accumulated in human body. Single unsaturated fatty acid can be catabolized completely All amino acids from protein sources can be catabolized by human body Lactose, sucrose and fructoses can be catabolized and merged to the glycolytic pathway

Poly-unsaturated fatty acids cannot be catabolized and may accumulated in human body.

When ATP level is high, which of the following will be inhibited? PEPCK FBP1 PFK1 ACC FAS-I

PFK1

PLP is a vitamin B6 derived multip-task cofactor involved in several biochemical reactions, including: Glycogen phosphorolysis Transamination that remove amino group in the process of catabolism of some amino acids Epinepherine triggered release of fatty acids A and B A, B, and c

A and B

Exam 2 Questions Flashcards

(106 cards)