32 Questions
What happens to apo-Cs during lipoprotein metabolism?
They are transferred to HDLs
What is the primary function of LDLs in lipoprotein metabolism?
To transport dietary cholesterol from the liver to peripheral tissues
What is the exclusive apolipoprotein of LDLs?
Apo-B-100
What is the primary site of LDL uptake in the body?
Liver
What is the role of LDL receptors in lipoprotein metabolism?
To mediate the uptake of LDLs by cells
What happens to the cholesterol esters in lysosomes after LDL uptake?
They are hydrolyzed to yield free cholesterol
What is the function of ACAT in lipoprotein metabolism?
To re-esterify excess intracellular cholesterol
What happens to the LDL receptor-apo-B-100 complex after LDL uptake?
It is broken down in lysosomes
What is the sole apoprotein present in LDLs?
apo-B-100
Where are HDLs synthesized?
Liver and small intestine
What is the primary function of HDLs?
To act as circulating stores of apo-C-I, apo-C-II and apo-E
What is the enzyme associated with HDLs that esterifies free cholesterol?
LCAT
What is the result of the action of LCAT on free cholesterol?
Generation of cholesteryl ester and lysolecithin
What is the result of HDLs acquiring cholesterol from macrophages?
Increase in HDL uptake and catabolism by the liver
How do HDLs acquire cholesterol from cells?
By extracting it from cell surface membranes
What is the effect of HDL-mediated cholesterol removal from cell surface membranes?
Decrease in intracellular cholesterol levels
What is the primary function of lipoproteins in the body?
To transport lipids in the blood to reach different tissues
What is the main component of the core of lipoproteins?
Triacylglycerol and cholesterol
What is the classification of lipoproteins based on ultracentrifugation?
Density
What is the main difference between chylomicrons and other lipoproteins?
Origin of formation
What is the primary lipid component of chylomicrons?
Triacylglycerols
What is the function of apo-C-II in chylomicrons?
To activate LPL in the presence of phospholipid
Where do chylomicrons enter the circulation?
Left subclavian vein
What is the origin of chylomicrons?
Intestinal mucosa
Where are free fatty acids (FAs) released from chylomicrons absorbed?
Tissues such as adipose and muscle
What happens to the glycerol backbone of triacylglycerols (TGs) after cleavage by lipoprotein lipase (LPL)?
It's returned to the liver and kidneys for conversion
Which apoprotein is necessary for chylomicron remnants to be recognized by the hepatic remnant receptor?
apo-E
What is primarily transported by Very Low Density Lipoproteins (VLDLs)?
Endogenously derived triacylglycerols to extra-hepatic tissues
How are triacylglycerols delivered to tissues by VLDLs?
Through the action of lipoprotein lipase (LPL)
Which of the following statements is accurate regarding chylomicrons?
They deliver dietary TGs to adipose tissue and muscle
What characteristic changes occur in VLDLs after the action of LPL and loss of certain apoproteins?
They transform into IDLs (VLDL remnants)
What is the main role of nascent chylomicrons in the body?
Deliver dietary TGs and cholesterol to various tissues
Learn about the structure and function of lipoproteins in transporting lipids in the blood. Understand how lipids are transported in a macromolecular complex to reach different tissues.
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