Deck 24: Carbohydrate, Lipid, and Protein Metabolism

Question 1

In the Cori cycle, compounds are cycled _____

A)from the muscles to the kidneys and back to the muscles.
B)from the muscles to the liver and back to the muscles.
C)from the kidneys to the liver and back to the kidneys.
D)from the liver to the brain and back to the liver.

Answer 1

B

Question 2

How much ATP results from the transformation of two (2)molecules of acetyl CoA to four (4)molecules of CO₂?

A)2 ATP molecules
B)5 ATP molecules
C)12 ATP molecules
D)20 ATP molecules
E)32 ATP molecules

Answer 2

D

Question 3

How many cycles of $\beta$ -oxidation are needed for complete catabolism of a saturated fatty acid with the chemical formula CH₃(CH₂)₁₈CO₂H?

A)1
B)9
C)10
D)18
E)20

Answer 3

9

Question 4

Which compound can rise to dangerously high levels in individuals with galactosemia?

A)galactase
B)glucose 1-phosphate
C)galactose
D)galactose 6-phosphate

Question 5

Which is not a step in the Cori cycle?

A)The catabolism of glucose in muscle forms pyruvate, which is reduced to lactate when the oxygen supply is limited.
B)Lactate is transported to the liver.
C)Oxidation of lactate forms pyruvate, which is then converted to glucose by the 10-step process of gluconeogenesis.
D)Pyruvate and NAD⁺ are transported to the muscle.

Question 6

Which food product does not rely on fermentation for its production?

A)cheese
B)beer
C)yogurt
D)yeast bread
E)All of the food products listed above rely on fermentation for their production.

Question 7

Which statement best describes the energy requirement for the conversion of a fatty acid to a thioester with coenzyme A in the $\beta$ -oxidation of a fatty acid?

A)This process requires energy.
B)This process is energy neutral - energy is neither required nor released.
C)This process releases energy.
D)Whether energy is required or released depends on the identity of the fatty acid being oxidized.

Question 8

$\beta$ -Oxidation of a fatty acid requires how many steps to cleave a two carbon acetyl CoA unit from the starting acyl CoA?

A)2
B)4
C)8
D)10
E)The number of steps required is dependent on the identity of the starting acyl CoA.

Question 9

How many molecules of ATP are formed during the complete catabolism of a saturated fatty acid with the chemical formula CH₃(CH₂)₂₀CO₂H?

A)32
B)98
C)140
D)148
E)150

Question 10

Which class(es)of compounds generates pyruvate as it is metabolized to acetyl CoA?

A)only fatty acids
B)only proteins
C)only carbohydrates
D)proteins and carbohydrates
E)fatty acids, proteins, and carbohydrates

Question 11

How much ATP results from the transformation of one glucose molecule to two (2)molecules of acetyl CoA?

A)2 ATP molecules
B)5 ATP molecules
C)12 ATP molecules
D)20 ATP molecules
E)32 ATP molecules

Question 12

How is pyruvate converted to acetyl CoA?

A)under aerobic conditions
B)under anaerobic conditions
C)during fermentation
D)This conversion is favorable under all of the conditions above.

Question 13

Which enzyme is capable of catalyzing the reaction shown?

A)propanol kinase
B)propanol isomerase
C)propanol dehydrogenase
D)propanol carboxylase

Question 14

How many molecules of coenzyme A are needed for complete catabolism of a saturated fatty acid with the chemical formula CH₃(CH₂)₁₈CO₂H?

A)1
B)9
C)10
D)18
E)20

Question 15

Glycolysis converts _____

A)polysaccharides to glucose.
B)glucose to pyruvate, which is then metabolized to acetyl CoA.
C)fatty acids to thioesters, which are then metabolized to acetyl CoA.
D)amino acids to urea.

Question 16

Which is not one of the three major products formed in glycolysis?

A)glucose
B)ATP
C)NADH
D)pyruvate

Question 17

The $\beta$ -oxidation of a fatty acid may be described as which type of metabolic pathway?

A)an anabolic pathway
B)a cyclic pathway
C)a spiral pathway
D)a linear pathway

Question 18

What is the starting material in step [1] in gluconeogenesis?

A)glucose
B)galactose
C)pyruvate
D)lactate
E)acetyl CoA

Question 19

How many molecules of NADH are formed during the complete catabolism of a saturated fatty acid with the chemical formula CH₃(CH₂)₂₀CO₂H?

A)1
B)10
C)11
D)20
E)22

Question 20

How many moles of ATP per gram of fatty acid are formed during the complete catabolism of a saturated fatty acid with the chemical formula CH₃(CH₂)₂₄CO₂H (molar mass 397 g/mol)?

A)0.0806 moles ATP / g fatty acid
B)0.297 moles ATP / g fatty acid
C)0.423 moles ATP / g fatty acid
D)0.443 moles ATP / g fatty acid
E)0.448 moles ATP / g fatty acid

Question 21

Glucogenic amino acids _____.

A)are converted to acetyl CoA.
B)are converted to glucose.
C)are catabolized to pyruvate or an intermediate in the citric acid cycle.
D)can be converted to ketone bodies.

Question 22

The reduction of acetaldehyde, shown below, is the last step in the fermentation process. What is the product of the reduction of acetaldehyde?

A)
B)
C)
D)

Question 23

Which factors increase the rate of gluconeogenesis?

A)high glycogen reserves
B)low carbohydrate diet
C)high carbohydrate diet
D)low oxygen concentration

Question 24

The first step in gluconeogenesis is the oxidation of lactic acid. What product is formed when lactic acid is oxidized?

A)
B)
C)
D)

Question 25

What metabolic intermediate is formed from the carbon skeleton of the amino acid asparagine?

A) $\alpha$ -ketoglutarate
B)oxaloacetate
C)citrate
D)succinyl CoA
E)fumarate

Question 26

Where does gluconeogenesis take place?

A)in the brain
B)in the muscle tissue
C)in the liver
D)in the kidney
E)Gluconeogenesis takes place in all of the locations listed above.

Question 27

Which compound is necessary for the oxidative deamination of the glutamate formed by transamination?

A)acetyl CoA
B)ATP
C)NADH
D)NAD⁺
E)FADH₂

Question 28

Which quantities need to be considered in determining the ATP yield from the complete catabolism of a fatty acid?

A)the ATP used up in the synthesis of the acyl CoA
B)the ATP generated from coenzymes produced during $\beta$ -oxidation
C)the ATP that results from the catabolism of each acetyl CoA
D)All of the quantities above need to be considered.

Question 29

What are the products formed in the transamination reaction shown?

A)
B)
C)
D)

Question 30

What product(s)is formed in a transamination reaction?

A)an amino acid
B)urea
C)ammonia
D)an $\alpha$ -keto acid
E)an amino acid and an $\alpha$ -keto acid are both formed

Question 31

What is ketosis?

A)the accumulation of ketone bodies
B)the synthesis of ketones from acetyl CoA
C)the reduction of ketone bodies
D)a medical condition that results from the consumption of acetone and/or other toxic ketones

Question 32

Which condition does not lead to increased levels of ketone bodies?

A)uncontrolled diabetes
B)starvation
C)high carbohydrate diet
D)All of the conditions above result in increased levels of ketone bodies.

Question 33

Which compound is not a ketone body?

A)acetoacetate
B)acetone
C) $\beta$ -hydroxybutyrate
D)acetyl CoA

Question 34

The first step in gluconeogenesis is the oxidation of lactic acid. What product is formed when lactic acid is oxidized?

A)
B)
C)
D)

Question 35

Which amino acid is classified as glucogenic?

A)leucine
B)proline
C)lysine
D)None of the amino acids are classified as glucogenic.

Question 36

How is the amino group of an amino acid lost as a result of transamination and oxidative deamination?

A)NH₂^-
B)NH₃
C)NH₄⁺
D)CH₃NH₂

Question 37

What metabolic intermediate is formed from the carbon skeleton of the amino acid valine?

A) $\alpha$ -ketoglutarate
B)oxaloacetate
C)citrate
D)succinyl CoA
E)fumarate

Question 38

Which process requires the coenzyme NADH?

A)glucose $\rightarrow$ pyruvate
B)pyruvate $\rightarrow$ acetaldehyde
C)pyruvate $\rightarrow$ lactate
D)pyruvate $\rightarrow$ acetyl CoA
E)More than one of the processes above requires the coenzyme NADH.

Question 39

How many molecules of ATP are formed per carbon atom in the fatty acid during the complete catabolism of a saturated fatty acid with the chemical formula CH₃(CH₂)₂₄CO₂H?

A)1.23 molecules ATP / carbon atom in the fatty acid
B)4.54 molecules ATP / carbon atom in the fatty acid
C)6.46 molecules ATP / carbon atom in the fatty acid
D)6.77 molecules ATP / carbon atom in the fatty acid
E)6.85 molecules ATP / carbon atom in the fatty acid

Question 40

Which amino acid is classified as ketogenic?

A)histidine
B)valine
C)arginine
D)leucine

Question 41

Fermentation is the aerobic conversion of glucose to ethanol and CO₂.

Question 42

Ketogenesis is the synthesis of ketone bodies from acetyl CoA.

Question 43

Step [9] in glycolysis, shown below, involves the dehydration of 2-phosphoglycerate. What is the structure of the dehydration product?

A)
B)
C)
D)

Question 44

Glucosamine, shown below, is a competitive inhibitor of the enzyme hexokinase, which catalyzes the phosphorylation of glucose in the first step of glycolysis (Eqn. 1 below). Which statement best describes the inhibition by glucosamine?

A)Glucosamine reacts with glucose, preventing glucose from binding to the active site of hexokinase.
B)Glucosamine binds to the active site of hexokinase, preventing glucose from binding.
C)Glucosamine stabilizes the active site of hexokinase, preventing glucose 6-phosphate from being released.
D)Glucosamine binds to the surface of hexokinase, causing a change in shape of the enzyme and the active site, preventing glucose from binding.

Question 45

When acetyl CoA levels exceed the capacity of the citric acid cycle, acetyl CoA is converted to ketone bodies.

Question 46

Six of the steps of gluconeogenesis use the same enzymes as used in glycolysis.

Question 47

Many cancerous tumors depend largely on glycolysis to supply their energy needs.

Question 48

Ketone bodies are produced in the kidneys, and since they are small molecules that can hydrogen bond with water, they are readily soluble in blood and urine.

Question 49

Individuals with galactosemia lack one of the enzymes necessary for converting galactose to glucose 6-phosphate.

Question 50

An abnormally high concentration of ketone bodies can lead to ketoacidosis-that is, an increase in the blood pH caused by the increased level of $\beta$ -hydroxybutyrate and acetoacetate.

Question 51

The phosphorylation of mannose to form mannose 6-phosphate requires energy from ATP.

Question 52

The glycerol formed from triacylglycerol hydrolysis is converted in two steps to dihydroxyacetone phosphate.

Question 53

Oxygen is needed to oxidize NADH to NAD⁺.

Question 54

The breakdown of amino acids forms NH₄⁺, which enters the urea cycle to form urea, and a carbon skeleton that is metabolized to either pyruvate, acetyl CoA, or an intermediate in the citric acid cycle.

Question 55

In glycolysis, two three-carbon molecules of pyruvate (CH₃COCO₂^-)are formed from each glucose molecule.

Question 56

Step [7] of glycolysis is shown below. Which statement concerning this step is true?

A)The hydrolysis of ATP provides the necessary energy for the removal of a phosphate group from 1, 3-bisphosphoglycerate.
B)The formation of 3-phosphoglycerate provides the necessary energy for the phosphorylation of ADP.
C)The energy required in the hydrolysis of 1, 3-bisphosphoglycerate is stored in ADP.
D)The hydrolysis of 1, 3-bisphosphoglycerate is an unfavorable reaction.

Question 57

Conceptually, gluconeogenesis is the reverse of glycolysis; that is, two molecules of pyruvate are converted to glucose by a stepwise pathway that passes through all of the same intermediates encountered in glycolysis.

Question 58

Catabolism of a fatty acid produces more than twice the energy per gram as glucose (in terms of moles of ATP generated).

Question 59

Gluconeogenesis is an anabolic process that synthesizes glucose from pyruvate.

Question 60

Gluconeogenesis is not a commonly used metabolic pathway when carbohydrate intake is high.

Question 61

Step [1] of the $\beta$ -oxidation of a fatty acid is considered an oxidation reaction even though the product has no additional C-O bonds.

Question 62

The urea cycle is a multistep pathway that converts ammonium ions to urea, (NH₂)₂C=O, in the kidneys.

Question 63

A glucogenic amino acid may also be a ketogenic amino acid.

Question 64

A carboxylase enzyme catalyzes the removal of carbon dioxide from a substrate.

Question 65

Low carbohydrate diets such as the Atkins diet induce the catabolism of stored fat for energy production to assist in weight loss.

Question 66

Glycolysis is a cyclic, 10-step pathway.

Question 67

Glycolysis occurs when the body has depleted its supplies of glucose and stored glycogen, and occurs during sustained physical exercise and fasting.

Question 68

Cortisol is an anti-inflammatory agent that also regulates carbohydrate metabolism. Cortisol contains a primary alcohol, a secondary alcohol, and a quaternary alcohol.

Question 69

The products that result when alanine is subjected to transamination followed by oxidative deamination are properly indicated below.

Question 70

Gluconeogenesis is simply the reverse of glycolysis.

Question 71

The major products of glycolysis are glucose and ATP.

Question 72

Transamination removes the amino group from an amino acid, leaving a carbon skeleton that contains only carbon, hydrogen, and oxygen atoms.

Question 73

A kinase enzyme catalyzes the transfer of a phosphate group from one substrate to another.

Question 74

In oxidative deamination, glutamate is re-converted to $\alpha$ -ketoglutarate, which can undergo transamination with another molecule of an amino acid and the cycle repeats.

Question 75

Glycolysis is an anaerobic pathway.

Question 76

The rate of glycolysis decreases when the body's ATP concentration is high.

Question 77

Cortisol is an anti-inflammatory agent that also regulates carbohydrate metabolism. Cortisol contains a primary alcohol, a secondary alcohol, and a quaternary alcohol.

Question 78

In fermentation, the six carbon atoms of glucose are converted to three molecules of ethanol.

Question 79

The overall result of transamination and oxidative deamination is to remove an amino group from an amino acid and form an ammonium ion, NH₄⁺.

Question 80

When oxygen is plentiful, pyruvate is converted to acetyl CoA, which can enter the citric acid cycle.