Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Bio 311 Biochemistry > Exam 2 Questions > Flashcards

Exam 2 Questions Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

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

A

Adipocytes: fatty acid synthesis will be stimulated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

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

A

Dehydration initiated deamination

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

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

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

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

6

8

2

4

12

A

2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

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

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

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

A

Converting glycogen phosphorylase a to phosphorylase b

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

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

A

Chylomicron carries a protein called Apo protein B100 on its surface

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

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

True

False

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

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

A

38 mole ATP

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

+

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

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

A

The Embden-Meyerhof-Parnas (EMP Pathway)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

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

A

Glycolysis in muscle and gluconeogenesis in liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

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

A

Decrease fatty acid synthesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Deficiency of fatty acyl-CoA dehydrogenase may lead to:

Stearate diarrhea

Vitamin D insufficiency

Infant diabetes

Infant sudden death

Malabsorption of essential fatty acids

A

Infant sudden death

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

General effects of glucagon on skeletal muscle include:

Glycolysis increases

Glycogen synthase activity increases

Glycated myoglobin increases

Glycogen breakdown increases

Glycogen synthesis is stimulated

A

Glycogen breakdown increases

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

The most important rate limiting enzyme for glycolysis is

Phosphofructose kinase 1 (PFK1)

Glyceraldehyde-3 phosphate dehydrogenase

Pyruvate kinase

Phosphoglycerate kinase

Hexokinases

A

Phosphofructose kinase 1(PFK1)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

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

A

Can be used by all tissues including neurons and hepatocytes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

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

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

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

Malic enzyme

Pyruvate carboxylase

Acetyl-CoA carboxylase

Malonyl-CoA

Fatty acid synthase (FAS)

A

Pyruvate carboxylase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

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

A

Gluconeogenesis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

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

True

False

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

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

True

False

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

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

A

Increase of intracellular NADPH levels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

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

True

False

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

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

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

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

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

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

A

Acetyl CoA carboxylation by ACC to form malonyl COA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

G6P phosphatase is an enzyme specifically expressed in hepatocytes

True

False

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Which of the following carbon sources cannot be used in gluconeogenesis in human cells?

Succinyl-CoA

Aspartate

Palmitate

Alanine

Glutamate

A

Palmitate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Basal level of metabolism is regulated by thyroids T3/T4

True

False

A

True

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

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

A

Vitamin B1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

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

A

Glucose 6-phosphate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

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

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

Ketone bodies can be utilized by the following organs, except for:

Brain

Liver

Heart

Kidney

Skeletal muscle

A

Liver

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

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

A hormone binding to cell surface receptor to synergize epinephrine effect

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

The oxidized glutathione protects enzymes from oxidative damage

True

False

A

False

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

Ref. Fig attached.
The one used directly in the initiation of biosynthesis of phosphatidic acid is:

a

b

c

d

e

A

a

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

In figure attached, glyceraldehyde-3 phosphate is:

a

b

c

d

e

A

d

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

In which compartment of cell does fatty acid synthesis occur?

Nucleus

Mitochondrion

Soluble cytoplasm (cytosol)

Golgi complex

Endoplasmic reticulum (ER)

A

Soluble cytoplasm (cytosol)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

Generally, the effects of epinephrine (adrenaline) on hepatocytes may include:

Inhibiting glycolysis

Enhancing glycogen synthase activity

Inhibiting glycogenolysis

Stimulating glycogen synthesis

Inhibiting glycogen breakdown

A

Inhibiting glycolysis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

About glycogenin expression and subcellular localization the right combination is:

Hepatocyte; cytosol

Adipocyte; mitochondrion

Myocyte; mitochondrion

Myocyte; endoplasmic reticulum

Cardiac myocyte; peroxisome

A

Hepatocyte; cytosol

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

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

A

Phosphoglycerate mutase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

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

A

In the mitochondrial matrix

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

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

A

F1,6BP broken by aldolase

44
Q

In figure attached, Dihydroxylacetone phosphate (DHAP) is:

a

b

c

d

e

A

b

45
Q

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

A

Vitamin B6

46
Q

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

A

Two NADPH and one pentose phosphate

47
Q

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

A

Glyceraldehyde-P dehydrogenase

48
Q

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

A

Dehydrogenation-hydration-dehydrogenation-cleavage

49
Q

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

A

Glut2

50
Q

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

A

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

51
Q

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

A

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

52
Q

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

A

Vitamin B6

53
Q

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

A

Acetyl CoA from beta oxidation

54
Q

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

A

Skeletal myocytes and adipocytes

55
Q

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

A

Condensation-reduction-dehydration-reduction

56
Q

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

A

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

57
Q

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

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

58
Q

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

A

Ketone bodies

59
Q

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

A

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

60
Q

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

A

Converting glycogen phosphorylase a to glycogen phosphorylase b

61
Q

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

A hormone binding to cell surface receptor to synergize epinephrine effect

62
Q

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

A

Soluble cytoplasm (cytosol) where NADPH level is high

63
Q

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

A

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

64
Q

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

A

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

65
Q

GIvcogen Storage Diseases may be caused by a defect of:

Glycogen synthase

Muscle PFK1

Lysosomal glucosidase

A and B

A, B, and C

A

A, B, and C

66
Q

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)

A

Pyruvate carboxylase (PC)

67
Q

Which of the following carbon sources cannot be used in gluconeogenesis in human cells?

Proline

Threonine

Palmitate

Glutamate

Aspartate

A

Palmitate

68
Q

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

A

Increase of intracellular NADPH levels

69
Q

Basal level of metabolic rate is mainly regulated by thyroid T3

True

False

A

True

70
Q

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

A

Acetyl CoA carboxylation by ACC to form malonyl-CoA

71
Q

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

A

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

72
Q

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

A

Gluconeogenesis

73
Q

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

A

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

74
Q

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

A

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

75
Q

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

A

Condensation-reduction-dehydration-reduction

76
Q

Ketone bodies can be utilized by the following organs, except for:

Brain

Heart

Skeletal muscle

Kidney

Liver

A

Liver

77
Q

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

A

Inhibiting glycolysis

78
Q

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

A

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

79
Q

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)

A

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

80
Q

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

A

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

81
Q

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

A

Adipocytes: fatty acid synthesis will be stimulated

82
Q

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

A

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

83
Q

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

A

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

84
Q

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

A

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

85
Q

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

A

False

86
Q

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

A

Skeletal myocytes and adipocytes

87
Q

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

A

Hexokinase IV

88
Q

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

A

It carries electrons and diffuses to complex I in ETC

89
Q

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

True

False

A

True

90
Q

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

A

Glycerol-3 phosphate

91
Q

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

A

Vitamin B6

92
Q

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

A

B and C

93
Q

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

A

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

94
Q

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

True

False

A

True

95
Q

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

A

Glut2

96
Q

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

A

AMP level will be decreased

97
Q

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

A

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

98
Q

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

A

Glycogen breakdown increases

99
Q

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

A

Chylomicron carries a protein called Apo- B100 on its surface

100
Q

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.

A

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

101
Q

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

A

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

102
Q

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

A

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

103
Q

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

A

Smooth endoplasmic reticulum

104
Q

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

A

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

105
Q

When ATP level is high, which of the following will be inhibited?

PEPCK

FBP1

PFK1

ACC

FAS-I

A

PFK1

106
Q

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

A and B

Bio 311 Biochemistry (3 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions