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Questions and Answers
What is the primary function of apolipoproteins in lipoproteins?
What is the primary function of apolipoproteins in lipoproteins?
- They store triglycerides in the liver.
- They increase the density of lipoproteins.
- They act as cholesterol precursors.
- They regulate transport and metabolism of lipoproteins. (correct)
Which lipoprotein is primarily responsible for reverse cholesterol transport?
Which lipoprotein is primarily responsible for reverse cholesterol transport?
- HDL (correct)
- Chylomicrons
- VLDL
- LDL
How do VLDL and IDL differ in their composition?
How do VLDL and IDL differ in their composition?
- IDL is richer in free cholesterol than VLDL.
- VLDL is depleted of triglycerides, while IDL is not.
- IDL is produced exclusively in the intestine.
- VLDL contains more triglycerides than IDL does. (correct)
What is the primary structural difference between ApoB-100 and ApoB-48?
What is the primary structural difference between ApoB-100 and ApoB-48?
Which lipoprotein class primarily functions to transport dietary lipids from the intestine?
Which lipoprotein class primarily functions to transport dietary lipids from the intestine?
In what way do lipoproteins vary based on density?
In what way do lipoproteins vary based on density?
What role does lipoprotein lipase play in the body?
What role does lipoprotein lipase play in the body?
What is a key characteristic of the composition of lipoproteins?
What is a key characteristic of the composition of lipoproteins?
Flashcards
Cholesterol
Cholesterol
Essential component of cell membranes and a precursor to sterols and steroids.
Triglycerides
Triglycerides
The storage form of fuel for energy production. Also a component of structural lipids.
Lipoproteins
Lipoproteins
Macromolecular aggregates that transport cholesterol and triglycerides in the blood.
Lipoprotein structure
Lipoprotein structure
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Apoproteins
Apoproteins
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Chylomicrons
Chylomicrons
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VLDL (Very Low-Density Lipoprotein)
VLDL (Very Low-Density Lipoprotein)
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LDL (Low-Density Lipoprotein)
LDL (Low-Density Lipoprotein)
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HDL (High-Density Lipoprotein)
HDL (High-Density Lipoprotein)
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ApoA-1
ApoA-1
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ApoB-100
ApoB-100
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ApoB-48
ApoB-48
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ApoE
ApoE
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ApoCII
ApoCII
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Lipoprotein Lipase (LPL)
Lipoprotein Lipase (LPL)
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Hepatic Lipase
Hepatic Lipase
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Study Notes
Major Lipids
- Cholesterol: Essential for cell membranes, precursor to sterols and steroids.
- Triglyceride (triacylglycerol): Storage form of energy, component of structural lipids.
- Both are transported in blood as lipoproteins.
Lipoproteins
- Lipoproteins: Transport cholesterol and triglycerides in blood. Spherical particles with a phospholipid, free cholesterol, and protein surface; core of triglycerides and cholesterol ester. Apoproteins (on surface) regulate transport and metabolism. Lipoprotein lipase system releases fatty acids from lipoproteins.
- Classes based on density, composition, and electrophoretic mobility. Density inversely correlates with size.
Lipoprotein Classes
- Chylomicrons: Transport dietary lipids from gut to liver and adipose tissue (primarily triglycerides).
- VLDL (Very Low Density Lipoprotein): Secreted by the liver, source of triglycerides.
- IDL (Intermediate Density Lipoprotein): Triglyceride-depleted VLDLs.
- LDL (Low Density Lipoprotein): Main blood cholesterol transporter distributing cholesterol throughout the body.
- HDL (High Density Lipoprotein): Secreted by liver, acquires cholesterol from peripheral tissues and atheroma (reverse cholesterol transport) and brings it back to the liver.
Apolipoproteins
- Apoproteins are "zip codes" directing lipoproteins.
- ApoA-1: Structural in HDL, ligand for ABCA1 receptor. Mediates reverse cholesterol transport, produced in liver and intestine.
- ApoB-100: Larger structure found in VLDL, IDL, LDL, LDL receptor ligand, made in liver.
- ApoB-48: Structural in chylomicrons, made in intestine.
- ApoE: Ligand for LDL remnant receptor. Involved in reverse cholesterol transport with HDL, brings cholesterol into the liver.
- ApoCII: Found in chylomicrons and VLDL. Binds to lipoprotein lipase to enhance TG hydrolysis (in capillaries).
Enzymes
- LPL (Lipoprotein Lipase): In capillaries of fat, cardiac, and skeletal muscle.
- HL (Hepatic Lipase): Produced in the liver, converts IDL to LDL.
Cholesterol Synthesis
- De novo synthesis is a major source of cholesterol. Liver synthesis is critical to total body burden.
Lipoprotein Disorders
- Diagnosis involves measuring lipids in serum after a 10-hour fast.
- Key indicator is the ratio of total cholesterol to HDL-cholesterol.
- Ratio >4.5 is associated with increased CVD risk.
- Ratio ≤ 3.5 is desirable.
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