Cholesterol Flashcards
(32 cards)
What is the rate limiting step in cholesterol synthesis?
HMG CoA to Mevalonic acid
What are the 8 remarkable steps in cholesterol synthesis?
Acetyl CoA to HMG CoA to Mevalonic acid to IPP to Farnesyl pyrophosphate to squalene to Lanosterol to Cholesterol
What enzyme catalyzes the rate limiting step of cholesterol synthesis?
HMG CoA reductase
Where is most of the cholesterol in the body found?
Brain (myelin sheaths)
Where is cholesterol found in the cell?
Outer leaflet of the cell membrane
What organ is responsible for most cholesterol biosynthesis?
Liver
What is the source of carbons in cholesterol?
Acetyl group of Acetyl CoA
What dietary element reduces cholesterol synthesis?
Fasting
What two hormones regulate cholesterol biosynthesis?
Glucagon inhibits; insulin promotes
In what other pathway does HMG-CoA appear?
Ketone body synthesis
Why don’t ketone body synthesis and cholesterol synthesis intersect?
Ketone in the matrix, cholesterol on the cytosol and sER
In what form is cholesterol stored?
Esterfied with long chain fatty acids
What 2 enzymes are involved in cholesterol storage?
ACAT LCAT
Where is ACAT?
Cytosol of the cell
Where is LCAT?
Lipoproteins
What is the primary FA for cholesterol storage?
Linoleic acid
How is cholesterol removed from the body?
Bile salts
What are the 2 primary bile salts?
Cholic acid and chenodeoxycholic acid
How are primary bile salts synthesized?
From cholesterol in the liver
What is the key regulatory enzyme for bile salt synthesis?
7a-hydroxylase
How are primary bile salts converted to secondary bile salts?
Intestinal bacteria
What secondary bile salt does cholic acid convert to?
Deoxycholic acid
What secondary bile salt does chenocholic acid convert to?
Lithocholic acid
What is special about lithocholic acid?
Only contains 1 hydroxyl group, not as effective
