Deck 24: Lipid Metabolism

Question 1

Which of the following is considered to be the so-called "good cholesterol"?

A)HDL
B)LDL
C)VLDL
D)Chylomicrons

Answer 1

HDL

Question 2

Chylomicrons are the least dense of all the lipoprotein/lipid combinations because

A)their lipoproteins nest together easily.
B)they have a high ratio of cholesterol to triacylglycerols.
C)they have the highest proportion of less dense lipid molecules.
D)there are many carbohydrate groups included in the external structure.
E)their amino acids are mostly hydrophobic.

Answer 2

they have the highest proportion of less dense lipid molecules.

Question 3

Glycerol produced as a byproduct of metabolism of lipids is converted to ________,which can be isomerized to a compound that can enter glycolysis or gluconeogenesis.

A)fatty acids
B)citrate
C)dihydroxyacetone phosphate
D)acetone
E)carbon dioxide

Answer 3

dihydroxyacetone phosphate

Question 4

All of the following are possible metabolic fates of the acetyl-SCoA intermediate except

A)synthesis of cholesterol.
B)the citric acid cycle and production of ATP.
C)gluconeogenesis.
D)lipogenesis.
E)ketogenesis.

Question 5

Which lipoprotein transports cholesterol to the liver to be recycled or excreted?

A)chylomicrons
B)ultra-high-density lipoproteins
C)high-density lipoproteins
D)low-density lipoproteins
E)very low-density lipoproteins

Question 6

Digestion of lipids begins in the ________,in a process catalyzed by ________.

A)mouth; salivary amylase
B)stomach; hydrochloric acid
C)small intestine; pancreatic lipases
D)large intestines; bile acids
E)adipocytes; triacylglycerol lipase

Question 7

In order for dietary lipids to be transported in an aqueous system,they are solubilized by

A)lipoproteins.
B)cholesterol.
C)lipases.
D)bile.
E)glycolipids.

Question 8

The first chemical step in the breakdown of triacylglycerols is

A)complete hydrolysis to fatty acids and glycerols.
B)partial hydrolysis to fatty acids,phosphates,and diacylglycerols.
C)oxidation of alcohol groups to carbonyls.
D)rearrangement to cholesterol derivatives.
E)none of the above

Question 9

The hormones ________ and ________ control the release of energy from stored triacylglycerol.

A)insulin; cortisone
B)adrenalin; glucagon
C)norepinephrine; cortisone
D)insulin; glucagon
E)adrenalin; norepinephrine

Question 10

What is the role of a chylomicron?

A)to transport triacylglycerols in the bloodstream
B)to synthesize cholesterol and other steroids
C)to move triacylglycerol across the cell membrane
D)to store excess triacylglycerols until they are needed
E)to transport acetyl-CoA from the cytosol to the mitochondria

Question 11

When fats are metabolized,the fatty acids enter the reactions of the

A)electron transport chain.
B)citric acid cycle.
C)glycolysis pathway.
D)β-oxidation process.
E)gluconeogensis.

Question 12

When energy from stored triacylglycerols is needed,they are ________,and then transported in the bloodstream via ________ as fatty acids.

A)hydrolyzed; high-density lipoproteins
B)hydrolyzed; albumins
C)oxidized; chylomicrons
D)oxidized; albumins
E)polymerized; high-density lipoproteins

Question 13

Where do the first chemical changes in the digestion of dietary fats take place?

A)mouth
B)stomach
C)small intestine
D)large intestine
E)liver

Question 14

Which is the correct term for the micelle-like structures which transport triglycerides in the bloodstream after digestion?

A)very low-density lipoproteins
B)low-density lipoproteins
C)high-density lipoproteins
D)liposomes
E)chylomicrons

Question 15

High density lipoproteins contain a greater amount of ________ than do low density lipoproteins.

A)protein
B)lipids
C)triglycerides
D)cholesterol
E)fatty acids

Question 16

Fatty acids from triacylglycerols can be ________ when energy is plentiful or ________ when energy is needed.

A)oxidized to produce acetyl-SCoA; stored as triacylglycerols in adipose tissue
B)stored as triacylglycerols in adipose tissue; oxidized to produce acetyl-SCoA
C)stored as cholesterol derivatives in adipose tissue; oxidized to produce glucose
D)reduced to hydrocarbons; isomerized to lower energy forms
E)diverted to gluconeogenesis; hydrolyzed to smaller molecules

Question 17

Which of the following lipoproteins is used solely for the transport of lipids in the blood?

A)chylomicrons
B)ultra-high-density lipoproteins
C)high-density lipoproteins
D)low-density lipoproteins
E)very low-density lipoproteins

Question 18

Which of the following substances are produced from hydrolysis of dietary fats in the small intestine?

A)bile salts
B)triglycerides
C)fatty acids
D)amino acids
E)monosaccharides

Question 19

Which lipoprotein transports cholesterol from the liver to sites where it is used in cell membranes or in steroid synthesis?

A)chylomicrons
B)ultra-high-density lipoproteins
C)high-density lipoproteins
D)low-density lipoproteins
E)very low-density lipoproteins

Question 20

Enzymes that hydrolyze lipids are ________; substances that emulsify lipids are ________.

A)insulin derivatives; lecithins
B)pancreatic lipases; bile salts
C)lipoproteins; lipases
D)proteases; chylomicrons
E)none of the above

Question 21

The correct order for these three processes leading from a fatty acid molecule in a cell needing energy to high energy molecules capable of meeting the energy need is
I.activation by reaction with coenzyme A
II.oxidation to acetyl-SCoA and reduced coenzymes
III.transport from cytosol into mitochondrial matrix

A)I,II,III.
B)II,III,I.
C)III,I,II.
D)I,III,II.
E)III,II,I.

Question 22

How many molecules of NADH are produced by the oxidation of a 10-carbon fatty acid?

A)6
B)10
C)4
D)3
E)15

Question 23

Where in the cell does beta-oxidation of fatty acids occur?

A)cell wall
B)cytosol
C)nucleus
D)mitochondria
E)liposome

Question 24

The activation of a fatty acid prior to entering into the beta-oxidation cycle requires the presence of what coenzyme?

A)malonyl CoA
B)FAD
C)ATP
D)cyclic AMP

Question 25

Which molecule is associated with transport of fatty acids into the mitochondrial matrix?

A)glycerol 3-phosphate
B)NADH
C)coenzyme A
D)carnitine
E)fatty acids

Question 26

Fatty acids are activated for breakdown by conversion to ________.

A)fatty acid SCoA's
B)triacylglycerides
C)fatty acid glycerol phosphates
D)fatty acid alkyl esters
E)none of the above

Question 27

The first step of the beta-oxidation cycle which is a dehydrogenation requires what coenzyme?

A)ATP
B)FAD
C)NAD⁺
D)NADP⁺

Question 28

The complete metabolism of one molecule of stearic acid,a fatty acid with 18 atoms of carbon,would produce ________ molecules of acetyl-SCoA.

A)8
B)9
C)10
D)16
E)18

Question 29

The complete metabolism of one molecule of stearic acid,a fatty acid with 18 atoms of carbon,would require ________ turns of the beta-oxidation cycle.

A)8
B)9
C)10
D)16
E)18

Question 30

Which type of molecule is the major form for long term storage of chemical energy in the body?

A)carbohydrates
B)proteins
C)triglycerides
D)steroids
E)waxes

Question 31

The complete metabolism of one molecule of myristic acid,a fatty acid with 14 atoms of carbon,would produce ________ molecules of acetyl-SCoA.

A)6
B)7
C)8
D)12
E)14

Question 32

Which statements are true for the process of β-oxidation?
I.It occurs in the mitochondria.
II.Acyl carrier proteins are involved.
III.NADPH is the coenzyme.
IV.The molecule increases in length by two carbons.
V.Energy is released in the process.

A)I,III,V
B)II,IV
C)I,V
D)I,II,III,IV,V
E)II,III,IV

Question 33

In comparing the potential energy of lipids and carbohydrates on a weight basis,it is correct to say that lipids provide

A)considerably less energy than carbohydrates.
B)slightly less energy than carbohydrates.
C)almost the same amount of energy as carbohydrates.
D)slightly more energy than carbohydrates.
E)considerably more energy than carbohydrates.

Question 34

Each oxidation during fatty acid catabolism directly produces one molecule of ________ and a fatty acid molecule that has been shortened by ________ carbon atom(s).

A)ATP; two
B)acetyl-SCoA; two
C)ATP; one
D)acetyl-SCoA; one
E)CO₂; three

Question 35

If lipid catabolism produces more acetyl-SCoA than the citric acid cycle can consume,but there is still a need for energy,the process of ________ takes over.

A)gluconeogenesis
B)ketogenesis
C)lipogenesis
D)steroid synthesis
E)transamination

Question 36

Which molecule is not associated with synthesis of triacylglycerides?

A)glycerol 3-phosphate
B)NADH
C)coenzyme A
D)carnitine
E)fatty acids

Question 37

Triacylglycerols are stored in

A)liposomes.
B)adipocytes.
C)high-density lipoproteins.
D)low-density lipoproteins.
E)membranes.

Question 38

After digestion and absorption,the molecules from dietary fats and oils are transported in the bloodstream as

A)glycerol.
B)fatty acids.
C)cholesterol.
D)citric acid.
E)enzymes.

Question 39

In the synthesis of triacylglycerides,fatty acids must react with ________ before they can attach to the glycerol backbone.

A)ATP
B)cholesterol
C)carnitine
D)coenzyme A
E)glycerol 3-phosphate

Question 40

The complete metabolism of one molecule of myristic acid,a fatty acid with 14 atoms of carbon,would require ________ turns of the beta-oxidation cycle.

A)6
B)7
C)12
D)14
E)16

Question 41

The formation of malonyl CoA from acetyl CoA and CO₂ also requires the presence of

A)cyclic AMP.
B)ATP.
C)glucose.
D)FAD.

Question 42

Match the following.
ketoacidosis

A)results from increased concentrations of ketone bodies in the blood
B)the catabolic reaction in which fatty acids are broken down two carbons at a time
C)the anabolic process of synthesizing fatty acids
D)presence of ketone bodies in the urine

Question 43

The molecule that is a precursor to the other ketone bodies is

A)acetone.
B)acetoacetate.
C)3-hydroxybutyrate.
D)malonyl-ACP.
E)malonyl-SCoA.

Question 44

The synthesis of fatty acids

A)takes place by simply the reverse reactions of the fatty acid spiral.
B)takes place in the same location within a cell as the fatty acid spiral.
C)takes place by different reactions than the reverse of the fatty acid spiral and in a different cellular location.
D)More than one response is correct.
E)No response is correct.

Question 45

Which statements are true for the process of lipogenesis?
I.It occurs in the mitochondria.
II.Acyl carrier proteins are involved.
III.NADPH is the coenzyme.
IV.The molecule increases in length by two carbons.
V.Energy is released in the process.

A)I,III,V
B)II,IV
C)I,III
D)I,II,III,IV,V
E)II,III,IV

Question 46

Ketogenesis occurs from a(an)

A)underproduction of ketone bodies.
B)consumption of too much sugar.
C)overproduction of acetyl CoA.
D)underproduction of acetyl CoA.
E)overproduction of ketone bodies.

Question 47

Compare the processes of β-oxidation of fatty acids and lipogenesis of fatty acids.

Question 48

Fatty acid synthesis occurs in the ________.

A)cytosol
B)mitochondria
C)cell membrane
D)endoplasmic reticulum
E)cell nucleus

Question 49

The intermediate that carries two-carbon units to be added to a fatty acid chain is

A)malonyl-SCoA.
B)fatty acyl-SCoA.
C)carnitine.
D)ATP.
E)glycerol 3-phosphate

Question 50

Which factor is the same in both lipogenesis and β-oxidation of fatty acids?

A)They occur in the same location in the cell.
B)They use the same enzymes.
C)They both involve NADPH and FAD.
D)They both depend on coenzyme A
E)They both occur two carbon atoms at a time.

Question 51

Match the following.
ketonuria

A)results from increased concentrations of ketone bodies in the blood
B)the catabolic reaction in which fatty acids are broken down two carbons at a time
C)the anabolic process of synthesizing fatty acids
D)presence of ketone bodies in the urine

Question 52

Ketone bodies are primarily produced in ________ cells.

A)brain
B)heart
C)liver
D)kidney
E)red blood

Question 53

When fatty acid metabolism creates more acetyl-CoA than can be handled in the citric acid cycle,the excess acetyl-CoA is converted into ________.

A)ketone bodies
B)amino acids
C)cholesterol
D)fatty alcohols
E)glycerol

Question 54

Which molecule is not a ketone body?

A)acetoacetate
B)acetone
C)3-hydroxybutyrate
D)methyl ethyl ketone
E)They are all ketone bodies.

Question 55

Match the following.
beta oxidation

A)results from increased concentrations of ketone bodies in the blood
B)the catabolic reaction in which fatty acids are broken down two carbons at a time
C)the anabolic process of synthesizing fatty acids
D)presence of ketone bodies in the urine

Question 56

High concentrations of ketone bodies in the bloodstream may indicate

A)diabetes mellitus.
B)starvation.
C)a decrease in the pH of the blood.
D)All responses are correct.
E)No responses are correct.

Question 57

Which has greater "energy density," carbohydrates or fats.Explain your answer in terms of molecular structure and net energy production.

Question 58

Match the following.
lipogenesis

A)results from increased concentrations of ketone bodies in the blood
B)the catabolic reaction in which fatty acids are broken down two carbons at a time
C)the anabolic process of synthesizing fatty acids
D)presence of ketone bodies in the urine