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Wednesday, January 09, 2008

highest percentage of triacylglycerol by weight is Chylomicrons

041. The human plasma lipoprotein containing the highest percentage of triacylglycerol by weight is:

1. VLDL

2. Chylomicrons

3. HDL

4. LDL

Answer

2. Chylomicrons

Reference:

Harper 26th Edition Page 206 Table 25.1

Lippincott 3rd Edition Page 227

Chaterjee 6th Edition Page 338 Table 21.2

Quality

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Status
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Discussion

Chylomicrons are large lipoprotein particles (having a diameter of 75 to 1,200nm) that are created by the absorptive cells of the small intestine. Chylomicrons transport lipids to adipose tissue where they are broken down by lipoprotein lipase.

Explanation

1. VLDL has 90 to 93 percent of lipids, mostly Triacyl Glycerol

2. Chylomicrons have 98 to 99 percent of lipids, mostly Triacyl Glycerol

3. HDL1 has just 68 % of lipids

4. LDL has 79 percent of lipids, mostly cholesterol

Comments

The chylomicrons are released by exocytosis from enterocytes into lacteals, lymphatic vessels originating in the villi of the small intestine, and are then secreted into the bloodstream, at the place where the lymphatic system falls into the blood stream, at the thoracic duct's connection with the left subclavian vein.

Tips

The following table has been adapted from Harper

Lipoprotein

Source

Diameter (nm)

Density (g/ml)

Composition

Main Lipid Components

Apolipoproteins

Protein (%)

Lipids(%)

Chylomicrons

Intestine

90-1000

<0.95

1-2

98-99

Tricacylglycerol

A-I, A-II, A-IV, B-48, C-I, C-II, C-III, E

Chylomicron remnant

Chylomicrons

45-150

<1.006

6-8

92-94

Tricacylglycerol, Phospholipids, Cholesterol

B-48, E

VLDL

Liver (intestine)

30-90

0.95 – 1.006

7-10

90-93

Tricacylglycerol

B-100, C-I, C-II, C-III

IDL

VLDL

25-35

1.006 – 1.019

11

89

Tricacylglycerol, Cholesterol

B-100, E

LDL

VLDL

20-25

1.019 – 1.063

21

79

Cholesterol

B-100

HDL

HDL1

Liver, Intestine, VLDL, Chylomicrons

20-25

1.019 – 1.063

32

68

Phospholipids, Cholesterol

A-I, A-II, A-IV, C-I, C-II, C-III, D, E

HDL2

10-20

1.063-1.125

33

67

HDL3

5-10

1.125-1.210

57

43

Preb HDL

<5

>1.210

A-I

Albumin/free faty acids

>1.281

99

1

Free fatty acids

HDL : High Density lipoproteins

IDL : Intermediate Density lipoproteins

LDL : Low Density lipoproteins

VLDL : Very Low Density lipoproteins

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