BCCB2000 Lecture 21 Questions

Question 1

Ketone bodies can not be catabolised in the following tissues: A. muscle B. liver C. brain D. heart E. all of the above

Answer 1

B. liver

Question 2

True or False? During starvation ketone bodies can take the place of glucose as a fuel for brain cells.

Answer 2

True

Question 3

In one pass of the β-oxidation of fatty acids the following occurs: A. two pairs of electrons are removed B. four H+ ions are removed C. two carbon atoms are removed D. one molecule of acetyl CoA is formed E. A and B only F. A and C only G. A and D only H. B and D only I. C and D only J. A, B, and D K. A, B, C, and D

Answer 3

K. A, B, C, and D

Question 4

A ketone functional group, and no other functional group, is found in which of the following ketone bodies: A. acetoacetate B. acetone C. β-hydroxybutyrate D. both A and B E. both B and C F. All A, B, and C

Answer 4

B. acetone

Question 5

Free fatty acids in the bloodstream are: A. bound to hemoglobin. B. present at levels that are independent of epinephrine. C. carried by the protein serum albumin. D. freely soluble in the aqueous phase of the blood. E. nonexistent; the blood does not contain free fatty acids.

Answer 5

C. carried by the protein serum albumin.

Question 6

The normal physiological range of ketone bodies in the blood is about 0.5 to 3 mg/dL (0.05 to 0.3mM). If the ketone bodies are so important as a source of fuel why are the levels are so low in the normal state? A. In the normal state production of ketone bodies would be lower than a stressed state such as diabetes or starvation. B. Ketone bodies are produced at a much slower rate than glucose. Hence, their concentration would be lower. C. Only the muscle can produce significant quantities of ketone bodies and this tissue is under the influence of the hormones insulin and glucagon. A lower level of ketone bodies means that insulin is not having an effect on the muscle tissue. D. Ketone bodies are an important source of energy even in normal state. The levels are low because the body is probably using the ketone bodies as quickly as they are produced. E. Ketone bodies are not an important source of energy in the normal state and so their blood levels are low

Answer 6

D. Ketone bodies are an important source of energy even in normal state. The levels are low because the body is probably using the ketone bodies as quickly as they are produced.

Question 7

Which lipid form is transported across the inner mitochondrial membrane before β-oxidation? A. acylcarnitine B. fatty acyl CoA C. acetoacetyl CoA D. lysophospholipid CoA

Answer 7

A. acylcarnitine

Question 8

Why is it undesirable to have high concentrations of free fatty acids in cells? A. They are unstable, free radicals that can react to form toxic substances. B. They polymerize easily and can cause the cytosol to become too gel-like. C. They are amphipathic and act as detergents that can degrade membranes. D. They inhibit the uptake of pyruvate by mitochondria.

Answer 8

C. They are amphipathic and act as detergents that can degrade membranes.

Question 9

The three stages of generating energy from fatty acids include: A. Stage 1: degradation of lipid by hormone sensitive lipase Stage 2: oxidation of glycerol Stage 3: respiratory chain B. Stage 1: alpha oxidation of fatty acids Stage 2: oxidation of glycerol Stage 3: Krebs Cycle oxidation C. Stage 1: beta oxidation of fatty acids Stage 2: glycolysis Stage 3: respiratory chain D. Stage 1: beta oxidation of fatty acids Stage 2: Krebs Cycle Stage 3: respiratory chain & oxidative phosphorylation E. Stage 1: beta oxidation of fatty acids Stage 2: glycolysis Stage 3: Krebs cycle

Answer 9

D. Stage 1: beta oxidation of fatty acids Stage 2: Krebs Cycle Stage 3: respiratory chain & oxidative phosphorylation

Question 10

Ketogenesis allows which of the following to occur: A. allows some of the oxaloacetate to be shunted away from the TCA cycle B. allows β-oxidation to continue by recycling CoA C. allows the TCA cycle to slow down D. A and B E. A, B, and C

Answer 10

B. allows β-oxidation to continue by recycling CoA

Question 11

True or False? Ketone bodies are normally broken down in the liver in preparation for excretion.

Answer 11

False

Question 12

How many cycles of β-oxidation are required to completely process a saturated C18 fatty acid? A. 6 B. 8 C. 9 D. 18

Answer 12

B. 8

Question 13

What main physiological conditions would stimulate production of ketone bodies and what key metabolite would initiate this production? A. Conditions of starvation, low carbohydrate diet, and diabetes would stimulate ketone body production. The key metabolite is acetyl CoA B. Conditions of starvation, high carbohydrate diet, and diabetes would stimulate ketone body production. The key metabolite is acetyl CoA C. Conditions of starvation, low carbohydrate diet, and ketosis would stimulate ketone body production. The key metabolite is acyl CoA D. Conditions of starvation, low carbohydrate diet, and diabetes would stimulate ketone body production. The key metabolite is acyl CoA E. Conditions of fasting, high carbohydrate diet, and obesity would stimulate ketone body production. The key metabolite is acetyl CoA

Answer 13

A. Conditions of starvation, low carbohydrate diet, and diabetes would stimulate ketone body production. The key metabolite is acetyl CoA

Question 14

Which of the following sequence of reactions (where the reactions proceed from left to right in sequence) are responsible for the beta oxidation of fatty acids? A. reduction, condensation, reduction, thiolysis B. oxidation, hydration, oxidation, thiolysis C. oxidation, reduction of NADPH, hydration, reduction of NADPH, thiolysis D. oxidation, condensation, oxidation, reduction E. consolidation, reduction, oxidation, addition of thiol group

Answer 14

B. oxidation, hydration, oxidation, thiolysis

Question 15

When a lipid (triacylglycerol) is hydrolysed it is split into a glycerol component and three fatty acids. Glycerol can be used to generate energy because: A. glycerol can enter the glycolytic pathway at the level of dihydroxyacetone phosphate B. glycerol can enter the Krebs cycle at the level of fumarate C. glycerol is oxidised immediately and its electrons are collected by NAD+ D. glycerol is oxidised immediately and its electrons collected by NADH E. glycerol is catalzyed by hormone sensitive lipase and generates ATP

Answer 15

A. glycerol can enter the glycolytic pathway at the level of dihydroxyacetone phosphate

Question 16

Which of the following does not contain a ketone functional group: A. acetoacetate B. 3-hydroxybutyrate C. acetone D. fructose E. dihydroxyacetone phosphate

Answer 16

B. 3-hydroxybutyrate

Question 17

Ketone bodies: A. are formed from amino acids B. are a source of metabolic fuel C. are formed from fatty acids D. are a source of other metabolic intermediates E. all of the above

Answer 17

E. all of the above

Question 18

Why are triacylglycerols able to provide more energy than carbohydrates (gram for gram)? A. The triacylglycerols have an extremely high group transfer potential. B. The carbohydrates are already in a more oxidized state than the triacylglycerols. C. The carbohydrates contain fewer carbon-carbon bonds. D. The triacylglycerols are less soluble in water than the carbohydrates.

Answer 18

B. The carbohydrates are already in a more oxidized state than the triacylglycerols.

Question 19

Fatty acids are oxidized in the ________. A. mitochondrial matrix B. cytosol C. endoplasmic reticulum D. mitochondrial inner membrane space

Answer 19

A. mitochondrial matrix

Question 20

Which of the following is not a stage of fatty acid synthesis? A. condensation of precursors B. rearrangement C. reduction D. dehydration

Answer 20

B. rearrangement

Question 21

If the 16-carbon saturated fatty acid palmitate is oxidized completely to carbon dioxide and water (via the β-oxidation pathway and the citric acid cycle), and all of the energy-conserving products are used to drive ATP synthesis in the mitochondrion, the net yield of ATP per molecule of palmitate is: Some of the following information may be useful: ATP = -31kJ/mol; 2ADP are produced during the activation of a fatty acid; about 1 acetyl CoA can generate about 13.5 ATP A. 3. B. 108. C. 25. D. 106. E. 1,000.

Answer 21

D. 106.

Question 22

True or False? Triacylglycerols are more efficient to store than carbohydrates because their hydrophobicity allows them to be stored in adipose cells without large amounts of bound water molecules.

Answer 22

True

Question 23

Transport of fatty acids from the cytoplasm to the mitochondrial matrix requires: A. ATP, coenzyme A, and hexokinase. B. ATP, carnitine, and coenzyme A. C. carnitine, coenzyme A, and hexokinase. D. ATP, carnitine, and pyruvate dehydrogenase. E. ATP, coenzyme A, and pyruvate dehydrogenase.

Answer 23

B. ATP, carnitine, and coenzyme A.

Question 24

There are four steps in the β-oxidation pathway. The following options show the reaction steps (identified by a number) in order from left to right. Choose the option that has the reaction types in the correct order that they occur in the β-oxidation pathway (you can use a reaction type more than once). Some reaction types are listed below: 1 condensation 2 oxidation 3 reduction 4 thiolysis 5 hydration 6 phosphorylation 7 rearrangement A. 1,7,2,2 B. 6,3,4,2 C. 1,2,3,5 D. 2,5,2,4

Answer 24

D. 2,5,2,4

Question 25

Which is not a ketone body? A. dihydroxyacetone B. acetoacetate C. acetone D. β-hydroxybutyrate

Answer 25

## Footnote A. dihydroxyacetone

Question 26

A calorie restricted diet with low glucose seems to target brain cancer cells and reduce their growth. This may work because: A. cancerous brain cells have defective mitochondria B. reduces the cancerous cells use of glucose C. non-cancerous tissues use the ketone bodies D. A and B E. A, B, and C F. None of the above

Answer 26

## Footnote E. A, B, and C

Question 27

The conversion of the fatty acid palmitate (C16) to carbon dioxide via β-oxidation, the citric acid cycle and oxidative phosphorylation yields the following important metabolites: A. ATP B. CO2 C. H2O D. A and B E. A and C F. B and C G. A, B, and C

Answer 27

## Footnote G. A, B, and C

Question 28

The major site of formation of acetoacetate from fatty acids is the: A. intestinal mucosa. B. adipose tissue. C. liver. D. muscle. E. kidney.

Answer 28

## Footnote C. liver.

Question 29

Saturated fatty acids are degraded two carbons at a time, producing acetyl-CoA. Under aerobic conditions, how many ATP molecules would be produced in beta oxidation of fatty acids per acetyl-CoA formed? Some of the following information may be useful: 1 NADH can produce about 2.5ATP; 1FADH2 can produce about 1.5ATP, the TCA cycle produces 1 GTP(ATP equivalent), pyruvate dehydrogenase can produce 1 NADH. A. 2 B. 3 C. 4 D. 5 E. 6

Answer 29

## Footnote C. 4

Question 30

The main function of the bile salts is to ________. A. transport lipids to the intestinal wall B. act as counterions for the ionized forms of lipids C. cleave the ester bonds in triacylglycerols to release free fatty acids D. form the surface layer of chylomicrons

Answer 30

## Footnote A. transport lipids to the intestinal wal