12: Cholesterol Phospholipid Synthesis

______ is a precursor of bile salts, steroid hormones, and vitamin D.

Cholesterol

The structural role of cholesterol is ______.

Rigidity

___% of lipids in a membrane are cholesterol.

50

The _____ synthesizes cholesterol from Acetyl CoA that is transported from the mitochondria to the cytoplasm via the citrate shuttle.

Liver

All of the Carbon atoms of cholesterol come from _________.

Acetyl CoA

__________ is the rate limiting enzyme of cholesterol biosynthesis.

HMG CoA reductase

Beta-hydroxy-beta-methylglutaryl-CoA (HMG-CoA) is catalyzed by HMG CoA reductase to be converted into ____________.

Mevalonate

_______ are part of the biosynthetic pathway of cholesterol. They are used to make a myriad of different things, such as vitamins, carotenoids, etc.

Activated isoprenes

Cholesterol and triacylglycerols (TG) are transported by ________ in the blood.

Lipoproteins

Specific lipoproteins that transport triacylglycerols?

Chylomicrons and Very Low Density Lipoprotein (VLDL)

Specific lipoproteins that transport cholesterol?

Low Density Lipoprotein (LDL) and High Density Lipoprotein (HDL)

What is the physiological role of the plasma lipoprotein chylomicron?

Dietary fat transport

What is the physiological role of the plasma lipoprotein very low density lipoprotein (VLDL)?

Endogenous fat transport

What is the physiological role of the plasma lipoprotein intermediate density lipoprotein (IDL)?

LDL precursor

What is the physiological role of the plasma lipoprotein low density lipoprotein (LDL)?

Cholesterol transport

What is the physiological role of the plasma lipoprotein high density lipoprotein (HDL)?

Reverse cholesterol transport

LDL transports cholesterol from the liver to _______.

Other tissues

HDL transports cholesterol from the liver for ______.

Disposal

Cholesterol synthesis is primarily regulated by controlling the activity of HMG CoA reductase, the rate-limiting enzyme, which converts HMG-CoA to ________.

Mevalonate

Cholesterol synthesis is regulated by ________ cholesterol levels.

Intracellular

______ is a disease where there are very high circulating cholesterol levels.

Familial hypercholesterolemia

A build up of cholesterol in the arteries is called ____________.

Severe atherosclerosis

Familial hypercholesterolemia is characterized by defective ____ receptors, with reduced or no functionality.

LDL

When LDL is not removed from blood _____ plaques form.

Atherosclerotic

Familial hypercholesterolemia increases risk for _____.

Heart attack or stroke

Partially functional LDL receptors in patients with familial hypercholesterolemia have reduced LDL clearance from circulation and _____ blood cholesterol.

Increased

Treatment for familial hypercholesterolemia are ________.

Statins (cholesterol lowering drugs)

Statins are competitive inhibitors of _____.

HMG CoA

Statins _______ HMG CoA reductase.

Inhibit

Statins _____ cholesterol synthesis.

Inhibit

Statins _____ LDL cholesterol levels.

Lower

Triacylglycerols and phospholipids are synthesized from a common pathway, the _________ pathway.

Kennedy

_________ is the starting substrate of triacylglycerol (TG) and phospholipid (PL) synthesis.

Glycerol-3-phosphate

__________ catalyze the sequential attachment of fatty acids to glycerol backbone (ester bond).

Acyltransferase

The only place within the body that you can synthesize phosphatidylcholine is in the ______.

Liver (methylation pathway)