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MCDB 310 > Exam 3 Problem Roulette > Flashcards

Exam 3 Problem Roulette Flashcards

1
Q

Where in the cell does Glycolysis take place in mammals?

A

In the Cytosol, since the enzymes are soluble

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2
Q

Which of the following is NOT an important catabolic product of pyruvate formed by glycolysis (i.e. what are the fates of pyruvate from glycolysis?)?

Glucose

Acetyl-CoA

Ethanol plus carbon dioxide

Lactate

A

Glucose

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3
Q

How many hexose phosphates are generated from 18 pentose phosphates during the non-oxidative phase of the Pentose Phosphate pathway?

9

6

15

18

3

A

15

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4
Q

Select the TRUE statement.

Gluconeogenesis in humans

Can take fatty acids to glucose.

helps decrease blood glucose after a carbohydrate-rich lunch

Is activated by the hormone insulin

requires PFK-1.

Cannot take acetyl CoA to glucose

A

Cannot take acetyl CoA to glucose

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5
Q

How many ATP molecules are required to convert one Glucose molecule to two 1,3-bisphosphoglycerate molecules?

2

1

8

None, ADP is required

4

A

2

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6
Q

What is the substrate of glycogen synthase for glycogen synthesis (that is, making glycogen longer)?

Glucose 1-phosphate

Glucose

Glucose 6-phosphate

Glucose 1,3-bisphosphate

UDP-glucose

A

UDP-glucose

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7
Q

The reaction in glycolysis that converts a ketose form to an aldose form is catalyzed by:

Phosphohexose isomerase

Phosphoglycerate mutase

Pyruvate kinase

Aldolase

Triose phosphate isomerase

A

Triose phosphate isomerase

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8
Q

The conversion of glucose-6-phosphate to ribulose-5-phosphate involves:

Hydrolysis of glucose-6-phosphate

Reduction of NADP+

Isomerization of glucose-6-phosphate

Carboxylation of glucose-6-phosphate

Reduction of glucose-6-phosphate

A

Reduction of NADP+

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9
Q

When a free glucose molecule first enters a cell (via the glucose transporter), the most likely first reaction catalyzed is:

Dehydration generating fructose

Phosphorylation of the C6 carbon using ATP

Isomerization into fructose

Phosphorylation of the C1 carbon using ATP

Dehydrogenation generating NADH

A

Phosphorylation of the C6 carbon using ATP

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10
Q

Glycolysis conserves metabolic energy in two different molecules. What is the correct pair of molecules and their net amounts produced by glycolysis?

4 ATP + 2 NADPH

2 ATP + 2 NADH

2 ATP + 4 NADH

4 ATP + 2 NADH

2 ATP + 2 NADPH

A

2 ATP + 2 NADPH

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11
Q

Which of the below helps convert glucose into a reactant for glycogen synthase?

cyclic AMP

CTP

GTP

UTP

ATP

A

UTP

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12
Q

The purpose of the oxidative phase of the pentose phosphate pathway is to:

oxidize glucose 6P, reduce NAD+, and as a result help generate energy (ATP) through oxidative phosphorylation

convert 6 ribose phosphates to 5 hexose phosphates

facilitate the Cori cycle.

provide intermediates for the citric acid cycle.

generate pentoses for the synthesis of nucleotides and nucleic acids.

A

generate pentoses for the synthesis of nucleotides and nucleic acids.

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13
Q

The electron acceptor in the steps that convert pyruvate to ethanol is:

pyruvate.

acetaldehyde.

NAD+.

TPP

ethanol.

A

acetaldehyde.

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14
Q

Which reaction of Glycolysis is unusual in that is uses inorganic phosphate as a reactant rather than phosphate/phosphoryl attached to another molecule?

Production of fructose 1,6-bisphosphate

Production of Glucose 6-phosphate

Production of Pyruvate

Production of 1,3-bisphosphoglycerate

Production of 3-phosphoglycerate

A

Production of 1,3-bisphosphoglycerate

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15
Q

Which is NOT a function of reactions of the Pentose Phosphate Pathway in the cell?

Facilitate photosynthesis

Conversion of a six-carbon sugar to a three-carbon sugar to produce ATP and NADH

Facilitates the reductive synthesis of fatty acids.

Helps counter oxidative damage during the transport of O2

Helps produce the sugars used to build DNA and RNA

A

Conversion of a six-carbon sugar to a three-carbon sugar to produce ATP and NADH

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16
Q

In animals, an enzyme UNIQUE to gluconeogenesis is:

Fructose-1,6 bisphosphatase

Glyceraldehyde 3-phosphate dehydrogenase

Enolase

Phosphoglyceromutase

Aldolase

A

Fructose-1,6 bisphosphatase

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17
Q

An enzyme used NEITHER in glycolysis NOR in gluconeogenesis is:

glucose 6-phosphatase.

pyruvate kinase.

phosphoglycerate kinase.

Phosphoglucomutase

hexokinase.

A

Phosphoglucomutase

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18
Q

It is critical to regenerate reaction intermediates in metabolic pathways for them to continue. In anaerobic conditions, what is the product when pyruvate is reduced to regenerate NAD+ in one form of fermentation?

Lactate

Glycogen

Glucose

ATP

NADH

A

Lactate

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19
Q

When lactic acid accumulates in muscles it is gradually carried away by the blood to the liver. What effect does lactic acid have on the respiratory rate?

It decreases the respiratory rate

Respiratory rate will initially decrease and the rapidly level off

It has no effect on the respiratory rate

It increases the respiratory rate

A

It increases the respiratory rate

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20
Q

Based on the last reaction of glycolysis, what can be said about the hydrolysis of PEP versus ATP

Hydrolysis of ATP is more spontaneous than hydrolysis of PEP

The rate of PEP hydrolysis is greater than the rate of ATP hydrolysis

The rate of ATP hydrolysis is greater than the rate of PEP hydrolysis

Free energy of hydrolysis is equal for PEP and ATP

Hydrolysis of PEP is more spontaneous than hydrolysis of ATP

A

Hydrolysis of PEP is more spontaneous than hydrolysis of ATP

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21
Q

The 1st and 3rd reactions of glycolysis are phosphoryl group transfers from ATP. What ion is also required for this reaction?

Mg2+

PO4 3-

Mn2+

H+

Ca2+

A

Mg2+

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22
Q

How is wasteful hydrolysis of a high-energy bond by hexokinase prevented?

Glucose doesn’t bind enzyme if enzyme is not already bound to ATP

Glucose doesn’t bind the enzyme during normal catalysis

ATP doesn’t bind enzyme if enzyme is not already bound to glucose

ATP doesn’t bind the enzyme during normal catalysis

Water cannot enter the active site of hexokinase

A

ATP doesn’t bind enzyme if enzyme is not already bound to glucose

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23
Q

How many net NADH molecules are produced from one glucose molecule in glycolysis?

2

None, no net NADH is made

8

4

1

A

2

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24
Q

Which of the following is a metabolic response to low blood glucose levels?

increased levels of insulin in blood

Increased Glucagon levels

Increased glycogen synthesis

Increased glycolysis

Decreased glycogen phosphorylase activity

A

Increased Glucagon levels

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25
Q

Under anaerobic conditions mammals utilize a process termed the “Cori Cycle” in which glucose is fermented to lactic acid in the muscle, and lactic acid is transported to the liver where it is converted back to glucose. During these processes, the net gain/loss of other metabolites is:

+2 ATP in muscle, -6 ATP in liver

+32 ATP in muscle

+2 ATP and +1 NADH in muscle, -6 ATP in liver and -1 NADH in liver

+2 ATP in muscle, -4 ATP in liver

+2 ATP and +1 NADH in muscle, -4 ATP in liver and -1 NADH in liver

A

+2 ATP in muscle, -6 ATP in liver

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26
Q

Which of the following molecules is a potent regulator of both Glycolysis and Gluconeogenesis?

NAD+

Glucose

Fructose 1,6-bisphosphate

Pyruvate

Fructose 2,6-bisphosphate

A

Fructose 2,6-bisphosphate

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27
Q

What is FALSE given what we know about the thermodynamics of the Fructose 1,6 bisPhosphatase reaction?

It is an irreversible step that doesn’t need coupling to another highly irreversible step

ATP has a higher phosphoryl group transfer potential than fructose 1,6 bisP

It is an example of a hydrolysis reaction

Pi is a product of the reaction

ATP has a lower phosphoryl group transfer potential than fructose 1,6 bisP

A

ATP has a lower phosphoryl group transfer potential than fructose 1,6 bisP

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28
Q

Which of the following enzymes is not bypassed in gluconeogenesis?

Enolase

Hexokinase

Pyruvate Kinase

Phosphofructokinase 1

A

Enolase

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29
Q

What general reaction type catalyzes the transfers a functional group from one position to another position on the same molecule?

Aldolases

Enolases

Dehydrogenases

Catalases

Mutases

A

Mutases

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30
Q

What enzyme catalyzes glycogen breakdown to glucose?

Glycogen phosphorylase

Glycogen phosphatase

Transglycolase

Glucose phosphatase

Glycogen kinase

A

Glycogen phosphorylase

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31
Q

Conversion of pyruvate to phosphoenolpyruvate requires an important cofactor that will come up often in the rest of the course. Which one of the following is that cofactor, a carrier of CO2?

Pyrophosphate (PPi)

Niacin

Magnesium

Biotin

Thiamine

A

Biotin

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32
Q

Which of the following is TRUE about aerobic glycolysis?

There is a net production of one NAD+ in this pathway

There is a net oxidation of glucose

It is the pathway used by yeast to produce ethanol

The carbons in pyruvate and glucose are in the same oxidation state

Pyruvate is readily converted to lactate which accumulates in the muscles

A

There is a net oxidation of glucose

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33
Q

The first reaction in glycolysis that results in the FORMATION of a compound with high phosphoryl transfer potential is catalyzed by:

pyruvate kinase

Glyceraldehyde 3-phosphate dehydrogenase (GAPDH)

phosphofructokinase-1.

phosphoglycerate kinase

Hexokinase

A

Glyceraldehyde 3-phosphate dehydrogenase (GAPDH)

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34
Q

The principle behind using PET scans (with a radiolabeled glucose analog) to diagnose cancer metastasis is the:

none of the other answers are correct

greater uptake of glucose by cancer cells than normal cells

greater increase in glycolytic enzymes in cancer cells than normal cells

formation of lactic acid in cancers due to hypoxic conditions

difference in tissue-density of the tumor and the surrounding normal tissue

A

greater uptake of glucose by cancer cells than normal cells

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35
Q

Gluconeogenesis requires the conversion of pyruvate (or lactate) to phosphoenolpyruvate in a bypass reaction. In which two cellular locations CAN this conversion take place (bearing in mind there are 2 alternative paths)?

Rough endoplasmic reticulum and cytosol

Golgi and rough endoplasmic reticulum

Plasma membrane and cytosol

Mitochondria and cytosol

Cytosol and Golgi

A

Mitochondria and cytosol

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36
Q

What products do you expect from a mixture of a 6-carbon and a 4-carbon-containing sugar-phosphate substrate in the presence of a transaldolase enzyme?

8 and 2 carbon containing sugar phosphate

Only one 10 carbon containing sugar phosphate

5 and 5 carbon containing sugar phosphate

7 and 3 carbon containing sugar phosphates

9 and 1 carbon containing sugar phosphates

A

7 and 3 carbon containing sugar phosphates

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37
Q

An enzyme that uses two PENTOSES as substrates to produce a HEPTOSE and a TRIOSE is a

Aldolase

Triose phosphate isomerase

Transaldolase

Transketolase

Kinase

A

Transketolase

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38
Q

Identify an important enzymes that function in anaerobic fermentation in yeast.

Glucose 6-phosphatase

Pyruvate decarboxylase

Alcohol carboxylase

Coenzyme A

Lactate dehydrogenase

A

Pyruvate decarboxylase

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39
Q

The oxaloacetate-to-malate-to-oxaloacetate chain of reactions of gluconeogenesis is important because

this is the only way lactate can be used to synthesize glucose.

It couples with a highly irreversible step to make the overall pathway irreversible

this chain-of-reactions is the only way in which gluconeogenesis can occur

It allows the apparent transfer of NADH from the mitochondria to cytosol

It allows stimulation of glycolysis and gluconeogenesis at the same time.

A

It allows the apparent transfer of NADH from the mitochondria to cytosol

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40
Q

How many of the intermediates of glycolysis is/are phosphorylated?

All of them

2

9

4

5

A

9

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41
Q

Which statement is FALSE regarding the reciprocal regulation of glycolysis and gluconeogenesis?

The regulation of the committed step of glycolysis is a major part of reciprocal regulation

Fructose 2,6 bisP is remarkable as it not only stimulates PFK-1 but it simultaneously stimulates FBPase-1

The enzyme responsible for synthesizing a regulator of reciprocal regulation contains not only the activity to make the regulator but also the activity to consume/degrade the regulator

The cell doesn’t want to simultaneously activate both glycolysis and gluconeogenesis

AMP can regulate both glycolysis and gluconeogenesis

A

Fructose 2,6 bisP is remarkable as it not only stimulates PFK-1 but it simultaneously stimulates FBPase-1

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42
Q

In which organisms does GLYCOLYSIS occur?

Only in heterotrophs and not in autotrophs

Aerobic organisms only

Anaerobic organisms only

Only in autotrophs and not in heterotrophs

Both aerobic and anaerobic organisms

A

Both aerobic and anaerobic organisms

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43
Q

What product of ethanol fermentation is also an important reactant in Glycolysis?

NAD+

Inorganic phosphate

Glucose

ATP

Glyceraldehyde 3-phosphate

A

NAD+

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44
Q

What is false about the Pentose Phosphate Pathway?

It is an irreversible pathway

It generates important cellular precursors

It is employed in rapidly dividing cells

It has two phases, an oxidative phase and a reductive phase

It is important for helping maintain the redox status of the cellular environmen

A

It has two phases, an oxidative phase and a reductive phase

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45
Q

What is one of the two products formed during Pyruvate fermentation by yeast?

Acetyl-CoA

Glucose

Carbon dioxide

NADH

Lactate

A

Carbon dioxide

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46
Q

An enzyme involved in glycogen breakdown is

glycogen phosphorylase.

transketolase

glycogen synthase.

Glycogenin

branching enzyme

A

glycogen phosphorylase.

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47
Q

Which one of these will NOT help in making the free energy change for a cellular process become more negative?

Accumulation of reactant

A decrease in the mass action ratio

Depletion of product

Accumulation of product

A

Accumulation of product

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48
Q

How many electrons and protons are transferred to NAD+ during a Dehydrogenation reaction in Biochemical pathways?

1 e- and 1 H+

2 e- and 2 H+

1 e- and 2 H+

4 e- and 4H+

2 e- and 1 H+

A

2 e- and 1 H+

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49
Q

Which of the following is a good indicator of large changes in the net rate of a metabolic pathway caused by small changes in specific substrate and product concentrations of a specific reaction of that pathway?

Compare ΔG’o for the steady state and the accelerated or inhibited reactions

Compare Vmax of the steady state to the Vmax for the accelerated or inhibited reactions

Compare the Vo for the steady state to the Vo for the accelerated or inhibited reactions

Compare the Turnover number to the Catalytic Efficiencies

Compare the Mass Action Ratio to K’eq for the reaction

A

Compare the Mass Action Ratio to K’eq for the reaction

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50
Q

Which molecule has the highest oxidation state?

Carbon dioxide (CO2)

Formaldehyde (CH2O)

Carbon monoxide (CO)

Methane (CH4)

Acetaldehyde (CH3COH)

A

Carbon dioxide (CO2)

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51
Q

Which of the following is NOT one of the 3 possible catabolic fates of Pyruvate that is formed in Glycolysis, as directly described in our text and others.

Fermentation to lactate

Complete oxidation to carbon dioxide and water through the Kreb’s Cycle

Oxidation to ribose 5-phosphate in the Pentose Phosphate Pathway

Fermentation to ethanol

A

Oxidation to ribose 5-phosphate in the Pentose Phosphate Pathway

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52
Q

Which of the following is not one of the three important groups that are donated by (transferred from) ATP under nucleophilic attack in metabolic reactions?

Cyclic monophosphoryl

Adenylyl

Phosphoryl

Pyrophosphoryl

A

Cyclic monophosphoryl

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53
Q

Select the TRUE statement

In a redox reaction, there is a transfer of electrons from one molecule/ion to another.

Reduction of a compound involves removal of electrons from it.

Dehydrogenase enzymes remove both two e- and two hydride ions from the same molecule.

In fermentation, pyruvate is oxidized to lactate.

Oxidation of a compound involves addition of electrons to it.

A

In a redox reaction, there is a transfer of electrons from one molecule/ion to another.

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54
Q

Phosphofructokinase is tightly regulated in glycolysis by allosteric modulators. Which of the following is NOT an allosteric modulator of PFK-1?

AMP

Fructose 2,6-bisphosphate

ATP

Glucose

ADP

A

Glucose

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55
Q

Which of the following is NOT one of the important metabolic “Fates” of pyruvate that is formed by glycolysis?

CO2

Lactate

Ethanol

NADH

Dihydroxyacetaone phosphate

A

Dihydroxyacetaone phosphate

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56
Q

Which statement is FALSE regarding the reciprocal regulation of glycolysis and gluconeogenesis?

The enzyme responsible for synthesizing a regulator of reciprocal regulation contains not only the activity to make the regulator but also the activity to consume/degrade the regulator

The regulation of the committed step of glycolysis is a major part of reciprocal regulation

The cell doesn’t want to simultaneously activate both glycolysis and gluconeogenesis

Fructose 2,6 bisP is remarkable as it not only stimulates PFK-1 but it simultaneously stimulates FBPase-1

AMP can regulate both glycolysis and gluconeogenesis

A

Fructose 2,6 bisP is remarkable as it not only stimulates PFK-1 but it simultaneously stimulates FBPase-1

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57
Q

It is uncommon for one molecule to act as both an activator and inhibitor in metabolism. Which of the following molecules both activates glycolysis and inhibits gluconeogenesis?

Glucose 6-phosphate

Pyruvate

Fructose 2,6-bisphosphate

NAD+

ADP

A

Fructose 2,6-bisphosphate

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58
Q

Which of the following is a feedback inhibitor of phosphofructokinase-1?

ATP

Glyceraldehyde-3-phosphate

Pyruvate

NADH

3-phosphoglycerat

A

ATP

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59
Q

Under which scenario will the rate of gluconeogenesis in the liver be much GREATER than that of glycolysis?

Low pyruvate concentration in muscle cells

increased blood sugar

Low ATP/AMP ratio in the muscle cells

High level of AMP in muscle cells

Starvation

A

Starvation

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60
Q

Which statement about free glucose storage is FALSE?

If all glucose were available as free glucose (not glycogen) the concentration gradient of intra- and extracellular glucose would be prohibitively large.

The free energy difference between intra- and extracellular free glucose would be difficult to overcome for glucose uptake by the cell.

Glucose is insoluble and cannot contribute to the osmotic balance of the cell.

All statements are true

A

Glucose is insoluble and cannot contribute to the osmotic balance of the cell.

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61
Q

When K’eq is ________ delta G’o is _______.

Greater than 1, negative

Less than 1, negative

0, Positive

0, negative

Greater than 1, positive

A

Greater than 1, negative

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62
Q

Sucrose and mannose both can enter Glycolysis through Feeder Pathways at what intermediate?

Glucose 6-phosphate

3-phosphoglycerate

Fructose 1,6-bisphosphate

Glucose 1-phosphate

Fructose 6-phosphate

A

Fructose 6-phosphate

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63
Q

Under low levels of glucose in the blood, the liver decreases its glycolytic rate and instead elevates the rate of

aerobic respiration

gluconeogenesis

glycogen synthesis

inhibition of glycogen phosphorylase

anaerobic respiration

A

gluconeogenesis

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64
Q

Which one would be an example of a highly spontaneous reaction?

Change in free energy is 0 kJ/mol

Change in free energy is -2 kJ/mol

Change in free energy is +20 kJ/mol

Change in free energy is -20 kJ/mol

Change in free energy is +2 kJ/mol

A

Change in free energy is -20 kJ/mol

65
Q

What is a chemical rationale for the release of a CO2 molecule during the oxidative phase of the Pentose Phosphate Pathway?

Reduction of pyruvate to ethanol results in release of CO2

Reduction of pyruvate to acetaldehyde results in release of CO2

Oxidation of CO by atmospheric oxygen produces CO2

Lipids and ribose 5-phosphates are reduced so that glucose can be oxidized to CO2

Beta keto acids formed upon oxidation decarboxylate spontaneously

A

Beta keto acids formed upon oxidation decarboxylate spontaneously

66
Q

What part of UTP is transferred to glucose 1P to form glucose-UDP for glycogen synthesis?

Phosphoryl group

UTP

Uracil

Uridylyl (UMP) group

UDP

A

Uridylyl (UMP) group

67
Q

The enzyme that catalyzes the branching of glycogen polymers catalyzes

Breakage of (α1 → 6) bonds

Synthesis of (α1 → 6) bonds

Synthesis of (α1 → 4) bonds

Synthesis of (beta1 → 4) bonds

Breakage of (beta1 → 4) bonds

A

Synthesis of (α1 → 6) bonds

68
Q

Which cofactor, or more properly prosthetic group, can perform as a one-electron or a two-electron carrier?

NADPH

Coenzyme A

Magnesium

FAD

NADH

A

FAD

69
Q

Which one is not a defining feature of a committed step of a pathway?

It is the only irreversible reaction in the pathway

The reaction has a free energy change in the cell that is negative

It is a highly regulated step in the pathway

It must be a spontaneous reaction under the conditions of the cell

Most feed-in metabolites enter the pathway before this step

A

It is the only irreversible reaction in the pathway

70
Q

The change in free energy (ΔG’o) for the above reaction is -16.7 kJ/mol. The reaction that comes next in glycolysis has a free energy change of 1.7 kJ/mol. The pH of these reactions is optimal near 7.4. What is the overall free energy change for these reactions?

-15 kJ/mol.

-18.4 kJ/mol

15 kJ/mol

-28.4 kJ/mol

18.4 kJ/mol

A

-15 kJ/mol.

71
Q

Glucose residues are removed from glycogen until a branch in the polysaccharide is reached. What specifically happens at the branch to permit more catabolism?

More glucose residues are removed at branches by the same glycosidases that remove non-branched glucose since the enzyme is multifunctional

Nothing happens since we cannot break any branches

“Debranching Enzyme” breaks the branches

The alpha-1,6-glycosidic linkage is converted to a beta-1,6-glycosidic linkage, and then a glycosidase cleaves it

A

“Debranching Enzyme” breaks the branches

72
Q

Glycolysis produces important products for other cells than the ones making it. What is the net production of ATP and NADH from one Glucose molecule?

1, 1

1, 2

4, 2

2, 4

2,2

A

2,2

73
Q

For the reaction A to B, DeltaG’° = –60 kJ/mol. The reaction is started with 10 mmol of A; no B is initially present. After 24 hours, analysis reveals the presence of 2 mmol of B, 8 mmol of A. Which is the most likely explanation?

A and B have reached equilibrium concentrations.

An enzyme has shifted the equilibrium toward A.

Formation of B is thermodynamically unfavorable.

B formation is kinetically slow; equilibrium has not been reached by 24 hours.

The result described is impossible, given the fact that DeltaG’° is –60 kJ/mol.

A

B formation is kinetically slow; equilibrium has not been reached by 24 hours.

74
Q

Glycogen synthase CANNOT

Add glucose to the reducing end of a glycogen polymer

form (alpha 1->4) linkages in a growing glycogen polymer

Get phosphorylated in the cell, ever.

Use a large growing glycogen polymer as a reactant

Use Glucose-UDP as a building block to grow a glycogen polymer

A

Add glucose to the reducing end of a glycogen polymer

75
Q

Pyruvate kinase transfers a phosphate group from phosphoenolpyruvate (PEP) to ADP, forming pyruvate and ATP. This reaction is essentially irreversible. Which of the following is the best explanation for the irreversible nature of this reaction?

The change in free energy for the overall reaction is large and negative

There is a different enzyme in the cell that synthesizes PEP

Binding of pyruvate to the active site is weak relative to binding of PEP

Reaction is coupled to pyruvate dehydrogenase reaction

Hydrolysis of ATP is highly favorable

A

The change in free energy for the overall reaction is large and negative

76
Q

If the standard change in free energy of the reaction is +73 kJoule/mole, what is true about this reaction at standard conditions?

will occur at a very fast pace.

will occur at a very slow pace.

will occur spontaneously.

will not occur spontaneously.

More information is needed to determine if the reaction will be spontaneous or not under these conditions.

A

will not occur spontaneously.

77
Q

Which statement is true about biochemical oxidation-reduction reactions?

Dehydrogenases typically remove two electrons and two hydrides.

Every oxidation must be accompanied by a reduction.

During oxidation a compound gains electrons.

They usually proceed through homolytic cleavage.

There are two commonly accessed oxidation states of carbon.

A

Every oxidation must be accompanied by a reduction.

78
Q

If the cell needs to replenish nucleoside triphosphates for suddenly increasing transcription, it will probably

increase only the steps that increase NADPH production to reduce ribose to deoxyribose

increase only the oxidative phase of the PPP

increase the flux through the complete PPP cyclic pathway

increase only the non-oxidative phase of the PPP

A

increase only the oxidative phase of the PPP

79
Q

When a mixture of glucose 6-phosphate and fructose 6-phosphate is incubated with the enzyme phosphohexose isomerase, the final mixture contains twice as much glucose 6-phosphate as fructose 6-phosphate. Which statement is MOST nearly correct, when applied to the reaction shown (R = 8.315 J/mol · K and T = 298 K)?

glucose 6-phosphate ⇋ fructose 6-phosphate

ΔG’°is incalculably large and positive.

ΔG’°is zero.

ΔG’° is –1.7 kJ/mol.

ΔG’° is +1.7 kJ/mol.

ΔG’°is incalculably large and negative.

A

ΔG’° is +1.7 kJ/mol.

80
Q

What enzyme will be activated by the AMP, which then activates other ATP-producing pathways?

Pyruvate kinase

Phosphofructokinase-1

Hexokinase IV

cAMP-dependent protein kinase

AMP-dependent protein kinase

A

AMP-dependent protein kinase

81
Q

Which of the following is also a high-energy bond that carries a lot of potential energy, making it relatively common in metabolism.

Biphosphate of NADH

Coenzyme A

Bisphosphates on phosphoinositides

Thioester

3’5’-phosphate linkage of cAMP

A

Thioester

82
Q

Which of the following is a metabolic response to high blood glucose levels?

Increased glycogen phosphorylase activity

Decreased glycolysis

Increased levels of insulin in blood

Decreased glycogen synthesis

Increased Glucagon levels

A

Increased levels of insulin in blood

83
Q

For the reaction, ΔG’° = +29.7 kJ/mol

L-malate + NAD+ → oxaloacetate + NADH + H+

The reaction as written:

may occur in cells at some concentrations of substrate and product.

can occur only in a cell in which NADH is converted to NAD+ by electron transport.

can never occur in a cell.

can occur in a cell only if it is directly coupled to another reaction for which ΔG’° is negative.

cannot occur because of its large activation energy.

A

may occur in cells at some concentrations of substrate and product.

84
Q

What term best characterizes the following: ADP + GTP → ATP + GDP

Phosphorylation

Adenylylation

Prenylation

Autophosphorylation

Transphosphorylation

A

Transphosphorylation

85
Q

What enzyme then removes glucose from glycogen in a phosphorolysis reaction?

Glycogen kinase

Inorganic pyrophosphatase

Glycogen phosphorylase

Glycogenin

Glycogen synthase

A

Glycogen phosphorylase

86
Q

What important reaction occurred to yield α-ketoglutarate from isocitrate

Substrate level phosphorylation and hydration

Decarboxylation and reduction of NAD+

Decarboxylation and hydration

Decarboxylation and oxidation of NADH

A

Decarboxylation and reduction of NAD+

87
Q

What Product of the Glyoxylate Cycle is a Reactant of the Citric Acid Cycle?

Aspartate

Succinate

Alpha-ketoglutarate

Aconitate

Glyoxylate

A

Succinate

88
Q

The conversion of 1 mol of glucose to 6 mol of CO2 via glycolysis and the citric acid cycle also yields _____ mol of NADH, _____ mol of FADH2, and _____ mol of ATP/GTP (total).

5, 1, 2

3, 1, 1

0, 0, 32

4, 1, 1

10; 2; 4

A

10; 2; 4

89
Q

Which of the following molecules is NOT associated with Ketone Bodies?

Acetoacetate

Beta-hydroxybutyrate

Acetyl-CoA

Acetone

A

Acetyl-CoA

90
Q

Acyl-CoA dehydrogenase passes electrons to the Electron Transferring Flavoprotein (ETF). What molecule is the immediate source of these electrons? That is, what molecule in ETF and acts as the last electron donor before the electron transport chain?

NADH

Fatty acyl-CoA

Acetyl CoA

FAD

Malonyl-CoA

A

FAD

91
Q

What enzyme catalyzes an isomerization reaction in the Citric Acid Cycle?

triose phosphate isomerase

citrate synthase

phosphoglycerate mutase

Succinyl CoA synthetase

Aconitase

A

Aconitase

92
Q

Full oxidation of a polyunsaturated fatty acid (18:2) gives rise to a product NOT given out by full oxidation of a monounsaturated fatty acid (18:1). This product is most likely:

water

NADP+

NADH

Acetyl-CoA

FADH2

A

NADP+

93
Q

What reaction uses Pi as a substrate? Reaction catalyzed by:

Glucose 6P dehydrogenase

Citrate synthase

Phosphofructokinase-1

Glyceraldehyde 3-phosphate dehydrogenase

Pyruvate carboxylase

A

Glyceraldehyde 3-phosphate dehydrogenase

94
Q

What two chemical mechanisms change pyruvate to acetyl-CoA in the pyruvate dehydrogenase complex?

Condensation and oxidation

Dehydrogenation and decarboxylation

Dehydrogenation and oxidation

Decarboxylation and condensation

Condensation and dehydrogenation

A

Dehydrogenation and decarboxylation

95
Q

Triglycerides and lipoproteins associate into what structure which is a vascular carrier of these lipids?

Glyoxysomes

Mitochondria

Bile salts

Chylomicrons

Peroxisomes

A

Chylomicrons

96
Q

Of the reactions that produce alpha-ketoglutarate and succinyl-CoA, both use what reaction mechanism?

Phosphorylation

Oxidative decarboxylation

Hydration

Dehydration

Dehydrogenation

A

Oxidative decarboxylation

97
Q

Which of the following does not serve as a coenzymes or prosthetic group for the Pyruvate Dehydrogenase Complex?

Coenzyme A

Lipoate

Thiamine pyrophosphate

Flavin adenine nucleotide

Biotin

A

Biotin

98
Q

The conversion of 1 mol of pyruvate to 3 mol of CO2 via pyruvate dehydrogenase and the citric acid cycle also yields _____ mol of NADH, _____ mol of FADH2, and _____ mol of ATP/GTP (total).

4; 1; 1

2; 2; 2

3; 2; 0

4; 2; 1

3; 1; 1

A

4; 1; 1

99
Q

Acyl chains with odd numbers of carbons can undergo oxidation, yielding which of the following as a final product molecule?

β-hydroxybutyrate

Propionyl-CoA

Acetyl CoA

Palmitate

Acetone

A

Propionyl-CoA

100
Q

Which of the following is not a component of Chylomicrons?

Phospholipids

Apolipoproteins

Triacylglycerols

Cholesterol

Bile Salts

A

Bile Salts

101
Q

Which one is used to partly digest ingested fats in the adipose tissues in response to low blood sugar?

Intestinal lipase

Hormone sensitive lipase

Lipoprotein lipase

HGM-CoA lyase

All the answers can perform this function

A

Hormone-sensitive lipase

102
Q

What combination of step and enzyme accurately depict a reaction in fatty acyl-CoA beta oxidation that uses a prosthetic group for catalyzing a redox reaction?

Step 1 – beta-hydroxyacyl-CoA dehydrogenase

Step 3 – beta-hydroxyacyl-CoA dehydrogenase

Step 1 – acyl-CoA dehydrogenase

Step 3 - acyl-CoA dehydrogenase

None of the combinations are correct

A

Step 1 – acyl-CoA dehydrogenase

103
Q

What is the direct role of NAD+ in the pyruvate dehydrogenase complex reaction cascade?

It oxidizes FADH2

It reduces FADH2

It reduces lipoate

It reduces TPP

It oxidizes TPP

A

It oxidizes FADH2

104
Q

Pools of which of the following enzyme(s) are found in both the mitochondrial matrix and the cytosol:

Succinate dehydrogenase

All of these

None of these

Lactate dehydrogenase

Malate dehydrogenase

A

Malate dehydrogenase

105
Q

Aconitase has an unusual chemical feature associated with 3 Cys residues. What is that feature?

Binding site for a competitive inhibitor

Iron-sulfur center

Disulfide linkage

Heme group

Cytochrome

A

Iron-sulfur center

106
Q

What is the common feature of these three reactions: isocitrate dehydrogenase, pyruvate dehydrogenase complex, and alpha-ketoglutarate dehydrogenase complex?

All three are highly endergonic

All three require prosthetic groups

All three produce CoA-SH

All three require NADH

All three produce CO2

A

All three produce CO2

107
Q

Which of the following enzymes is not involved in a decarboxylation reaction?

All of the above are involved in decarboxylation reactions

Isocitrate dehydrogenase

Alpha-ketoglutarate dehydrogenase

Pyruvate dehydrogenase

Malate dehydrogenase

A

Malate dehydrogenase

108
Q

What class of lipids is the primary target of beta-oxidation?

Triglycerides

Phospholipids

Sphingolipids

Glycerols

Glycerophospholipids

A

Triglycerides

109
Q

Which one of these fatty acids when oxidized would give rise to propionyl-CoA as a product?

(18:3)

(16:2)

(20:1)

(22:0)

(17:0)

A

(17:0)

110
Q

High cellular concentrations of what molecule would INHIBIT the entry of pyruvate via acetyl CoA into the citric acid cycle?

NADH

AMP

Calcium (Ca2+)

Coenzyme A

oxaloacetate

A

NADH

111
Q

Which of the following pathways produces Succinyl-CoA for the Kreb’s Cycle?

Oxidation of polyunsaturated fatty acids

Beta-oxidation of fatty acids with even numbers of carbons

Oxidation of phospholipids

Beta-oxidation of fatty acids with odd numbers of carbons

Oxidation of monounsaturated fatty acids

A

Beta-oxidation of fatty acids with odd numbers of carbons

112
Q

When a fatty acid of chemical formula 22:1 Δ9 is oxidized using the beta-oxidation pathway, the number of FADH2 produced will be:

9

8

11

22

10

A

9

113
Q

How is a specific reaction in the Citric Acid Cycle that uses an achiral substrate able to form only one enantiomeric form of a chiral product?

The energy of ATP hydrolysis drives chiral center formation.

Only one enantiomer of the substrate can fit in the active site

All enzymes, their active sites, and their complexes with the transition state of a reaction are chiral.

Substrate-level phosphorylation.

Water can be chiral at 55.5 M concentration

A

All enzymes, their active sites, and their complexes with the transition state of a reaction are chiral.

114
Q

A coenzyme/cosubstrate required for formation of an acyl-CoA and an acetyl-CoA from beta-ketoacyl-CoA during beta oxidation

CoA-SH

NAD+

FAD

All other answers are correct.

H2O

A

CoA-SH

115
Q

What additional reactant is required for oxidation of polyunsaturated fatty acids compared with saturated fatty acids?

NAD+

ATP

FAD

NAD(P)H

Acetyl-CoA

A

NAD(P)H

116
Q

Which one of the following enzymatic activities would be decreased by the decreased uptake of thiamine by chronic alcohol users?

alpha-Ketoglutarate dehydrogenase complex

Malate dehydrogenase

Isocitrate dehydrogenase

Succinate dehydrogenase

Fumarase

A

alpha-Ketoglutarate dehydrogenase complex

117
Q

If the FREE FATTY ACID (16:1) is catabolized completely, to carbon dioxide and water, the NET yield of ATP (i.e., ATP potential from NTP, NADH, and FADH2) per molecule of FREE FATTY ACID is _____ ATP.

108

106.5

106

104.5

112

A

104.5

118
Q

What the two additional reaction mechanisms are performed on the unsaturated fatty acid, Linoleic acid (18:3) in the correct order, to permit its entry into beta-oxidation?

Isomerization, Reduction

Oxidation, reduction

Reduction, Isomerization

Oxidation, hydration

Isomerization, Oxidation

A

Isomerization, Reduction

119
Q

What class of proteins is associated with chylomicrons and functions to target lipids for delivery to specific tissues?

Apolipoproteins

Carnitines

Perilipins

Serum albumin

Phospholipases

A

Apolipoproteins

120
Q

Which of the following important reactants is NOT produced by the first 5 steps of the Kreb’s Cycle?

Succinate

All of the above are produced by the first 5 steps

CO2

GTP

NADH

A

All of the above are produced by the first 5 steps

121
Q

Malonate is a competitive inhibitor of succinate dehydrogenase. If malonate is added to a mitochondrial preparation that is oxidizing pyruvate as a substrate, which of the following compounds would you expect to immediately decrease in concentration?

Isocitrate

Succinate

Pyruvate

Citrate

Fumarate

A

Fumarate

122
Q

How many acetyl-CoA molecules are obtained from linoleic acid [18:2 (Δ 9,12)] via beta-oxidation?

7

The number cannot be determined with the given information

18

9

16

A

9

123
Q

Where does ketogenesis occur in primates such as humans?

adipose tissue

skeletal muscle

the brain

the liver

both the liver and adipose tissue

A

the liver

124
Q

Which one of the following is not occurring in the Citric Acid Cycle?

Substrate-level phosphorylation

FADH2 formation

Oxidative decarboxylation

C-C bond formation reaction

Acetyl CoA formation

A

Acetyl CoA formation

125
Q

What valuable Citric Acid Cycle intermediate is made by PEP carboxykinase and by PEP carboxylase, a molecule that is usually in low concentration in cells?

Oxaloacetate

Fumarate

Pyruvate

Citrate

Malate

A

Oxaloacetate

126
Q

Which one of the following is not part of the Citric acid cycle?

Oxidation of pyruvate

Formation of a C-C bond

Synthesis of NTP

Use of FAD+ as a substrate

Simultaneous oxidation and loss of CO2

A

Oxidation of pyruvate

127
Q

What molecule serves as an example of how an intermediate on one energy-generating metabolic pathway can regulate the flux through ANOTHER energy-generating metabolic pathway?

Mg2+

Fructose 1,6 bisP

ATP

Citrate

O2

A

Citrate

128
Q

The reaction in the beta-oxidation of fatty acids that is most similar to the reaction catalyzed by fumarase in the citric acid cycle is catalyzed by:

acyl CoA dehydrogenase

enoyl CoA hydratase

thiolase

hormone-sensitive lipase (HSL)

beta-hydroxy acyl CoA dehydrogenase

A

enoyl CoA hydratase

129
Q

Which of the following intermediates can be used to produce Phosphoenolpyruvate that could be used in Gluconeogenesis?

Malate

Succinyl CoA

Pyruvate

Succinate

Oxaloacetate

A

Oxaloacetate

130
Q

-oxidation comprises a repeating set of 4 reactions that remove acetyl groups from acyl chains. Which reaction involves a thiolate in a cleavage reaction?

None of the steps involve a thiolate group

Step 1

Step 2

Step 3

Step 4

A

Step 4

131
Q

A coenzyme/cosubstrate required for formation of a beta-ketoacyl-CoA from a beta-hydroxyacyl-CoA is

FAD

NAD+

CoA-SH

All other answers are correct.

TPP

A

NAD+

132
Q

GTP is produced by the Kreb’s Cycle. What important enzyme can then produce ATP from the GTP if there is sufficient ADP present?

Nucleoside diphosphate kinase

Protein kinase A

F-type ATPase

Adenylate kinase

Adenylate cyclase

A

Nucleoside diphosphate kinase

133
Q

Triacyl glycerol stores energy not only in the form of fatty acids but also in the form of a product that can be metabolized to undergo

Entire PPP cycle

Oxidative phase of the PPP

The ATP-generating steps of glycolysis

Non-oxidative phase of the PPP

None of the answers is correct

A

The ATP-generating steps of glycolysis

134
Q

Plants can make glucose out of fatty acids because

They encode odd-numbered fatty acids that are not found in animals

They are able combine the glyoxylate cycle to the CAC in the mitochondria

The rate of fatty acid oxidation is greater in plants that in animals

The oxaloacetate concentrations are much higher in plants

None of the other answers is true.

A

They are able combine the glyoxylate cycle to the CAC in the mitochondria

135
Q

What is the location for ketone body biogenesis?

Hepatocytes

Glial cells

Adipocytes

Myocytes

Neurons

A

Hepatocytes

136
Q

How many ATP equivalents are required to produce an activated fatty acid in order for it to enter beta-oxidation?

1

None, because GTP is the source of energy

3

One for beta-oxidation and two for omega-oxidation

2

A

2

137
Q

The redox reaction catalyzed by which of these enzymes uses a cofactor/co-enzyme/prosthetic group that is different than that of all the other ones? (In other words, all the other enzymes use the same redox cofactor/co-enzyme/prosthetic group)

glucose 6-phosphate dehydrogenase

malate dehydrogenase

succinate dehydrogenase

isocitrate dehydrogenase

glyceraldehyde 3-phosphate dehydrogenase

A

succinate dehydrogenase

138
Q

Which of the following statements is TRUE regarding the thermodynamics of the Citric Acid Cycle?

The Cycle is an endergonic set of reactions

The free energy input is significantly positive, but the equilibrium indicates that the Cycle will continue uninterrupted

All the reactions contain free energy changes that are near 0, which is one reason why the cycle can continue uninterrupted

It is an exergonic set of reactions

Only the final 3 steps are significantly negative, but the sum of these three free energy changes drive the rest of the Cycle

A

It is an exergonic set of reactions

139
Q

Which of the following would contain Glyoxysomes?

Algae

Gram-negative bacteria

Vertebrates

Yeast

Leafy plants

A

Leafy plants

140
Q

Chylomicrons are associated with lipid metabolism. What is their function?

Oxidation of fatty acyl chains in plants and algae

Oxidation of fatty acyl-CoA that have odd numbers of carbons

Transport of triglycerides in the blood

Assembly of acyl chains and glycerol into triacylglycerols

Transport of fatty acyl chains from the gut lumen to the vascular space

A

Transport of triglycerides in the blood

141
Q

Malonate is a competitive inhibitor of succinate dehydrogenase. If malonate is added to a mitochondrial preparation that is oxidizing pyruvate as a substrate, which of the following compounds would you expect to immediately decrease in concentration?

Citrate

Pyruvate

Isocitrate

Succinate

Fumarate

A

Fumarate

142
Q

A substrate required for formation of a beta-hydroxyacyl-CoA from trans-Δ2-enoyl-CoA is

FAD

H2O

CoA-SH

All other answers are correct.

NAD+

A

H2O

143
Q

Which reaction of the Citric Acid Cycle combines a 4-carbon and a 2-carbon intermediate to form a 6-carbon intermediate?

2

3

5

1

4

A

1

144
Q

Citric Acid Cycle happens in the _____ and glycolysis happens in the _____.

Plasma membrane, Cytosol

Mitochondria, Cytosol

Cytosol, Cytosol

Cytosol, Mitochondria

Cytosol, Plasma membrane

A

Mitochondria, Cytosol

145
Q

Plants contain a lot of fatty acids with odd numbers of carbons. Oxidation of these lipids produces Propionyl-CoA.

Complete oxidation of this molecule requires extra reactions that produce what Krebs Cycle intermediate as the final product?

Malate

Citrate

Succinate

Succinyl-CoA

Alpha-ketoglutarate

A

Succinyl-CoA

146
Q

All redox reactions of the citric acid cycle are linked to the reduction of nicotinamide-containing molecule EXCEPT that catalyzed by:

succinate dehydrogenase.

α-ketoglutarate dehydrogenase complex

malate dehydrogenase.

pyruvate dehydrogenase

isocitrate dehydrogenase.

A

succinate dehydrogenase.

147
Q

The three-carbon product from the hydrolysis of triacylglycerols is fed into glycolysis as:

dihydroxyacetone-1,3- bisphosphate.

Glyceraldehyde 3-phosphate

acetyl CoA.

glucose-6-phosphate.

glucose.

A

Glyceraldehyde 3-phosphate

148
Q

The isomerization of citrate to isocitrate:

protects cells from the toxic effects of arsenite ion.

is an oxidation reaction.

converts a tertiary alcohol, which cannot easily be oxidized, to a secondary alcohol that can be oxidized.

is a major regulatory step for the citric acid cycle.

is the only unnecessary step of the citric acid cycle.

A

converts a tertiary alcohol, which cannot easily be oxidized, to a secondary alcohol that can be oxidized.

149
Q

The fatty acid molecules obtained in a blood draw from a healthy individual will be found to be

Bound to a protein belonging to the albumin family.

Water-soluble as they are much smaller and more hydrophilic than triacylglycerol

Bound to bile salt micelles.

Bound to carnitine.

Bound to myoglobin.

A

Bound to a protein belonging to the albumin family.

149
Q

How many molecules of acetyl CoA are produced from a single molecule of glucose for participation in the Krebs cycle?

4

2

1

0

3

A

2

150
Q

A combination of a cyclic pathway in the glyoxysome/peroxisome and a cyclic pathway in the mitochondria is used

For the synthesis of fatty acids from acetyl-CoA in animals.

To perform oxidative phosphorylation

for gluconeogenesis in a hibernating bear

For gluconeogenesis starting with fatty acids

For the synthesis of fatty acids from TCA cycle intermediates.

A

For gluconeogenesis starting with fatty acids

151
Q

One reason that fatty acids make an excellent source of fuel is that they carry more energy per carbon atom than do carbohydrates. This is because:

The carbons in fatty acids are more hydrophobic than the carbons in carbohydrates.

The carbons in fatty acids are lighter than carbons in carbohydrates.

The carbons in fatty acids are more polar than the carbons in carbohydrates.

The carbons in fatty acids are more oxidized than the carbons in carbohydrates.

The carbons in fatty acids are more reduced than the carbons in carbohydrates.

A

The carbons in fatty acids are more reduced than the carbons in carbohydrates.

152
Q

Anaplerotic reactions

produce pyruvate and citrate to maintain constant levels of citric acid cycle intermediates

all of the other answers are correct

recycle pantothenate used to make CoA

Use citric acid cycle intermediates to make other useful precursors in the cell

produce citric acid cycle intermediates

A

produce citric acid cycle intermediates

153
Q

What is the primary function of the chylomicron in absorption of fats?

It helps solubilize fats so that they can be delivered from the intestinal cells to adipocytes via the blood

phosphoryl group transfer

It is a lipase, which is an enzyme that breaks down lipids into fatty acids

It is produced in the liver and is important for gluconeogenesis

it is a coenzyme required for the Citric Acid Cycle

A

It helps solubilize fats so that they can be delivered from the intestinal cells to adipocytes via the blood

154
Q

What is the primary function of bile?

It helps solubilize fats in the diet so that they can be broken down and absorbed into the body

it is a coenzyme required for the Citric Acid Cycle

It is produced in the liver and is important for gluconeogenesis

phosphoryl group transfer

It is a lipase, which is an enzyme that breaks down lipids into fatty acids

A

It helps solubilize fats in the diet so that they can be broken down and absorbed into the body

155
Q

The reaction of the citric acid cycle that involves substrate-level phosphorylation forms the following metabolite as a product:

fumarate.

alphaketoglutarate

succinyl CoA

succinate

isocitrate.

A

succinate

156
Q

Triglycerides are carried in the blood by ______ while free fatty acids in the blood bind to and are carried by _______.

Chylomicrons, Perilipins

Chylomicrons, Serum albumin

Perilipins, Serum albumin

Perilipins, Chylomicrons

Serum albumin, perilipins

A

Chylomicrons, Serum albumin

157
Q
A

MCDB 310 (3 decks)

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