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 26^th Edition Page 206 Table 25.1

Lippincott 3^rd Edition Page 227

Chaterjee 6^th Edition Page 338 Table 21.2

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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