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Cellular Metabolism > Lipid digestion, absorption and transport > Flashcards

Lipid digestion, absorption and transport Flashcards

1
Q

What happens to Virgin Coconut Oil (medium chain fatty acid) during digestion?

A. it gets readily absorbed in the body
B. it is transported in the body by albumin
C. it is brought to the liver via the portal vein where it will be oxidized
D. All of the above

A

D

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2
Q

Which of the following lipoprotein particles contains the greatest amount of lipids as percentage of weight?

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

A

A

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3
Q

Which apoprotein is LDL’s marker?

A. A1
B. B48
C. B100
D. E

A

C

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4
Q

Reverse cholesterol transport is catalyzed by LCAT. What
apoprotein serves as cofactor for this enzyme?

A. Apo AI
B. Apo CII
C. Apo CIII
D. Apo E

A

A

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5
Q

Cells metabolize LDL via receptor mediated endocytosis. LDL receptors respond to specific apolipoproteins. The apoprotein with the highest affinity to LDL receptors is?

A. apoprotein B100
B. apoprotein CI
C. apoprotein CII
D. apoprotein E

A

A

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6
Q

What food should you eat if you want to decrease your cholesterol levels?

A. Cassava
B. Oat bran
C. White rice
D. Bread

A

B

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7
Q

Bab was curious to know what her cholesterol profile was after listening to the lecture on lipid digestion. She knows that hypercholesterolemia runs in her family. She had a fasting lipid profile done at PGH and the results were as follows:

Total cholesterol: 300 mg/dl
HDL: 65 mg/dl
Triglycerides: 175 mg/dl

However, there was no mention of the LDL level. Help Bab compute for her LDL value.

A. LDL = 190 mg/dl
B. LDL = 410 mg/dl
C. LDL = 112 mg/dl
D. LDL = 200 mg/dl

A

D

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8
Q

What is the only mechanism by which cholesterol is excreted in the human body?

A. Via the secretion of sweat
B. Via the synthesis of lipoproteins
C. Via the formation of bile salts
D. Via the secretion of lipases

A

C

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9
Q

Which of the following organs receives the LEAST amount of fatty acids from the hydrolysis of chylomicrons by lipoprotein lipase?

A. Heart
B. Adipose tissue
C. Skeletal muscles
D. Liver

A

D

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10
Q

Which of the following apoproteins is important in the degradation of LDL in the liver by serving as the recognition protein of the LDL receptor?

A. Apo B-48
B. Apo B-100
C. Apo C-I
D. Apo E

A

B

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11
Q

Which of the following lipoproteins is synthesized by both the liver and the intestines?

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

A

D

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12
Q

Which of the following statements regarding the digestion and absorption of cholesterol is FALSE?

A. Liver synthesis of cholesterol exceeds the amount of cholesterol obtained from the diet
B. Fifty percent of cholesterol that enters the ileum is absorbed in the body.
C. Dietary cholesterol is incorporated into micelles together with triglycerides.obtained from the diet.
D. Cholesterol in the enterocytes is excreted back in the intestinal lumen as cholesteryl esters.

A

D

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13
Q

Eating food rich in fats may have several effects in our body. Which of the following dietary fatty acids is known for its health benefits in lowering serum triglycerides?

A. Palmitic acid
B. Oleic acid
C. Linoleic acid
D. Eicosapentaoic acid

A

D

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14
Q

Cells metabolize LDL via receptor mediated endocytosis. LDL receptors respond to specific apolipoproteins. The apoprotein with the highest affinity to LDL receptors is?

A. apoprotein B100
B. apoprotein CI
C. apoprotein CII
D. apoprotein E

A

A

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15
Q

What enzyme is very important in the cholesterol transport and which serves to transfer cholesterol from HDL to VLDL and LDL, which can be returned to the liver for endocytosis?

A. Lecithin:cholesterol acyltransferase (LCAT)
B. Cholesteryl ester transfer protein (CETP)
C. Lipoprotein lipase (LPL)
D. Acyl-coenzyme A:cholesterol acyltransferase (ACAT)

A

B

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16
Q

Which of the following statements best describe hormone sensitive lipase?

A. Hormone sensitive lipase breaks the C-H bonds found in fatty acids
B. Hormone sensitive lipase is located in the endothelial cells lining blood vessel walls
C. Hormone sensitive lipase is active in the phosphorylated form
D. Hormone sensitive lipase is activated by Insulin

A

C

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17
Q

Which of the following factors are associated with increased digestibility and absorption of dietary lipids?

a. High fat consumption
b. Older age of consumption
c. Longer fatty acid length
d. More saturated fat content

A

C

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18
Q

Which of the following is TRUE about essential fatty acids?

a. They can be synthesized by humans
b. They cannot be synthesized by plants
c. They do not maintain membranes
d. They have double bonds at delta12 and delta15

A

D

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19
Q

Which of the ff statements regarding Omega-3 is FALSE?

a. Synthesized in the human body
b. Linoleic acid can be synthesized de novo in the human body
d. Linoleic acid can be derived from the diet

A

b

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20
Q

Which of the following inhibits LPL?

a. A-II
b. C-I
c. C-II
d. C-III

A

D

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21
Q

Enzyme that digests lipids in the mouth

A

Lingual lipase

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22
Q

On which lipids does lingual lipase act on?

A

Short and medium chains

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23
Q

Enzyme that digests lipids in the stomach

A

Gastric lipase

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24
Q

On which lipids does gastric lipase act on?

A

Short and medium chains

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25
Q

Why are lingual lipases essential in neonates?

A

Lingual lipases are needed to digest the lipids found in milk, the only nutrition an infant can take in since birth to a few months

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26
Q

What is the importance of emulsification in the small intestines?

A

Emulsification increases the surface area of hydrophobic lipid droplets so that the digestive enzymes which work at the interface of the droplet and the surrounding aqueous solution can act effecticely

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27
Q

Which complementary mechanisms carry out emulsification?

A

Bile salts and peristalsys

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28
Q

Which organ secretes bile?

A

Liver

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29
Q

Bile salts are derived from which lipids?

A

Cholesterol

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30
Q

Which stimulates the gallbladder to contract in order to transfer bile salts into the small intestines?

A

CCK

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31
Q

What stimulates the secretion of CCK?

A

The entry of acidic gastric contents into the duodenum

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32
Q

The entry of acidic gastric contents into the duodenum stimulates the secretion of which substances?

A

CCK and bicarbonate

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33
Q

What is the function of bicarbonate?

A

Neutralizes the acid from the stomach and deactivates gastric lipase

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34
Q

Which stimulates the secretion of pancreatic lipase?

A

CCK

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35
Q

How many carbons do short and medium chains have?

A

12 and below

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36
Q

Bile salts convert dietary fats into lipid bilayers of bile salts and TAGs. T/F

A

F

It converts them into mixed micelles.

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37
Q

Pancreatic lipase converts TAGs to what substances?

A

2-Monoacylglycerides, free fa

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38
Q

Mixed micelles can diffuse into intestinal cells. T/F

A

T

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39
Q

Lipid-binding proteins in the blood, responsible for transport of TAGs, phospholipids, cholesterol, and cholesteryl esters between organs

A

Apolipoproteins

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40
Q

In lipoproteins, hydrophobic lipids are at the surface while hydrophilic protein side chains and lipid head groups are at the core. T/F

A

F

The hydrophobic lipids are at the core while the hydrophilic protein side chains and lipid head groups are at the surface

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41
Q

Arrange lipoproteins in ascending density

A

Chylomicrons, VLDL, IDL, LDL, HDL

42
Q

Arrange lipoproteins in ascending size

A

HDL, LDL, IDL, VLDL, chylomicrons

43
Q

Lipoprotein with most protein content

A

HDL

44
Q

Lipoprotein with highest lipid content

A

Chylomicrons

45
Q

Most of the lipid content of chylomicrons are what type?

A

TAG

46
Q

Lipoprotein which contains most cholesterol

A

LDL

47
Q

Lipoprotein containing most TAG

A

Chylomicrons

48
Q

Unique apolipoprotein of chylomicrons

A

Apo B-48

49
Q

Unique apolipoprotein of VLDL, LDL, IDL

A

Apo B-100

50
Q

Which lipoprotein has no Apo B?

A

HDL

51
Q

Which lipoprotein has Apo B-100?

A

VLDL, IDL, LDL

52
Q

Which lipoprotein has Apo B-48?

A

Chylomicrons

53
Q

The specific function of a lipoprotein is determined by which three factors?

A

Point of synthesis, lipid composition, apolipoprotein content

54
Q

Where are chylomicrons synthesized?

A

In ER of epithelial enterocytes

55
Q

Chylomicrons from the intestinal cells enter the blood stream through which vessel?

A

Left subclavian

56
Q

Lipoprotein with lowest protein content

A

Chylomicrons

57
Q

Lipoprotein with lowest TAG content

A

HDL

58
Q

Lipoprotein with lowest cholesterol content

A

Chylomicrons

59
Q

Major apoprotein of HDL

A

Apo A-I

60
Q

Which apolipoprotein activates lipoprotein lipase?

A

Apo C-II

61
Q

Which lipoproteins have Apo C-II?

A

Chylomicrons, VLDVL, HDL

62
Q

Contents of chylomicron remnants

A

Cholesterol, Apo B-48, Apo E

63
Q

Where is the chylomicron remnant absorbed?

A

Liver

64
Q

Uptake of chylomicron remnants in the liver is through which cell mechanism?

A

Endocytosis

65
Q

Where are VLDLs synthesized?

A

Hepatic cells

66
Q

Which organ removes VLDV remnants in circulation?

A

Liver

67
Q

IDL are VLDL remnants. T/F

A

T

68
Q

When VLDL loses TAGs, to which is it converted?

A

IDL

69
Q

When IDL from VLDL loses more TAGs, to which is it converted?

A

LDL

70
Q

Where does HDL originate?

A

Hepatocytes and enterocytes

71
Q

Which lipoprotein has no cholesteryl esters?

A

HDL

72
Q

Which lipoprotein contais LCAT?

A

HDL

73
Q

Function of LCAT

A

Catalyzes formulation of cholesteryl esters from lecithin (phosphatidylcholine) and cholesterol

74
Q

Which lipoprotein transforms cholesterol and lecithin of VLDL and chylomicrons to cholesteryl esters and brings them to the liver?

A

HDL

75
Q

A mature HDL is taken up by the liver by which mechanism?

A

Endocytosis

76
Q

The most abundant component of chylomicrons is which of the following?

(A) ApoB-48
(B) Triglyceride
(C) Phospholipid
(D) Cholesterol
(E) Cholesterol ester
A

B

77
Q

The conversion of nascent chylomicrons to mature chylomicrons requires which of the following?

(A) Bile salts
(B) 2-Monoacylglycerol
(C) Lipoprotein lipase
(D) High-density lipoprotein
(E) Lymphatic system
A

D

78
Q

The apoproteins B-48 and B-100 are similar with respect to which of the following?

(A) They are synthesized from the same gene.
(B) They are derived by alternative spicing of the same hnRNA.
(C) ApoB-48 is a proteolytic product of apoB-100.
(D) Both are found in mature chylomicrons.
(E) Both are found in very-low-density lipoproteins.

A

A

79
Q

Bile salts must reach a particular concentration within the intestinal lumen before they are effective agents for lipid digestion. This is because of which of the following?

(A) The bile salt concentration must be equal to the triglyceride concentration.
(B) The bile salt solubility in the lumen is a critical factor.
(C) The ability of bile salts to bind lipase is concentration dependant.
(D) The bile salts cannot be reabsorbed in the ileum until they reach a certain concentration.
(E) The bile salts do not activate lipase until they reach a particular concentration.

A

D

80
Q

Type III hyperlipidemia is caused by a deficiency of apoprotein E. Analysis of the serum of patients with this disorder would exhibit which of the following?

(A) An absence of chylomicrons after eating
(B) Above-normal levels of VLDL after eating
(C) Normal triglyceride levels
(D) Elevated triglyceride levels
(E) Below-normal triglyceride levels

A

B

81
Q

Which one of the following statements about the
absorption of lipids from the intestine is correct?

A. Dietary triacylglycerol is partially hydrolyzed and absorbed as free fatty acids and monoacylglyc­erol.
B. Dietary triacylglycerol must be completely hydrolyzed to free fatty acids and glycerol before absorption.
C. Release of fatty acids from triacylglycerol in the intestine is inhibited by bile salts.
D. Fatty acids that contain ten carbons or less are absorbed and enter the circulation primarily via the lymphatic system.
E. Formation of chylomicrons does not require pro­tein synthesis in the intestinal mucosa.

A

A

82
Q

The form in which most dietary lipids are packaged and exported from the intestinal mucosal cells is as:

A. free fatty acids.
B. mixed micelles.
C. free triacylglycerol.
D. 2-monoacylglycerol
E. chylomicrons.
A

E

83
Q

Where are LPLs located?

A

Walls of blood capillaries

84
Q

LPL is anchored to the endothelium by which GAG?

A

Heparan sulfate

85
Q

Unesterified fatty acids are transported in circulation using which molecule?

A

Serum albumin

86
Q

A family of proteins that restrict access to lipid droplets stored in adipocytes to prevent untimely lipid mobilization

A

Perilipins

87
Q

Which hormones activate the hormone-sensitive lipase?

A

Epinephrine and glucagon

88
Q

Hormone-sensitive lipase is active when phosphorylated. T/F

A

T

89
Q

Which protein phosphorylates hormone-sensitive lipase?

A

Perilipin A, and PKA

90
Q

About 95% of the biologically available energy of TAG resides in their three long chin FA; only 5% is contributed by the glycerol moiety. T/F

A

T

91
Q

FAs of 12 or fewer carbons enter the mitochondria without the help of membrane transporters. T/F

A

T

92
Q

In the transport of FA into the mitochondria, what is the first reaction catalyzed?

A

Synthesis of fatty acid-CoA from FFA and CoA

93
Q

Which enzyme catalyzes the reaction producing fatty aciy-COA to transport FA into the mitochonria?

A

Acyl-CoA synthetase

94
Q

To what molecule must fatty acid be converted to in order to cross the mitochondrial membranes?

A

Fatty-acyl carnitine

95
Q

Which enzyme converts fatty acids to fatty acyl-carnitine?

A

Carnitine acyltransferase I

96
Q

Your mom read that PUFAs are good for your health.
You recommend the following, except

\A. corn
B. coconut
C. tuna
D. Salmon

A

B

97
Q

Orlistat is a weight-reducing drug that reduces amount of fat absorbed by 30%. Which of the following lipase is affected?

A. lipoprotein lipase
B. pancreatic Lipase
C. Gastric Lipase
D. Hepatic Lipase

A

B

98
Q

What is the role served by B-100 in relation to LDL and its receptor?

A. Part of the apolipoprotein structure
B. Cofactor for enzyme
C. Inhibitor of enzyme
D. Ligand for interaction

A

D

99
Q

Whcih apolipoprotein is also known as the cholesteryl ester transfer protein (CETP), the protein which facilitates the exchange of triglycerides for cholesterol from VLDL
particles to HDL particles

A. Apo A-1
B. Apo C-1
C. Apo D
D. Apo E

A

D

100
Q

Apolipoproteins are readily shuttled from triglyceride-
rich apolipoproteins to HDL and back again. Which of the
following apolipoproteins is not exchangeable?

A. Apo A-1
B. Apo C-1
C. Apo D
D. Apo E

A

C

101
Q

Which of the following digestive enzymes is responsible for hydrolyzing triacylglycerols to form free fatty acids and monoacylgycerols? It is also the enzyme inhibited by the anti-obesity drug Orlistat.

A. Lingual lipase
B. Gastric lipase
C. Pancreatic lipase
D. Lipoprotein lipase

A

D

Cellular Metabolism (8 decks)

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