Cholesterol Flashcards
Where is cholesterol found in the cell
Between membrane fatty acid chains
What does cholesterol do in the cell
Forms loose cross-links to increase rigidity/reduce fulidity
What is cholesterol a precursor to
Bile salts
Steroid hormones
What percentage of cholesterol is in the free form
30%
What transports esterified cholesterol
Lipoproteins
Is esterified cholesterol found in membranes
no
What is an organic molecule produced by combining an acid with an alcohol
Ester
What is the primary site of cholesterol synthesis
Liver
Where in the cell is cholesterol synthesized
Cytosol
What is the rate limiting enzyme of cholesterol synthesis
HMG CoA reductase
What is the product of HMG CoA reductase
mevalonate
How is HMG CoA reductase regulated
Active: non-phosphorylated
Inactive: Phosphorylated
What is HMG CoA converted into
Mevalonate
What is Mevalonate converted into
Squalene
What is Mevalonate converted into
Cholesterol
What gets turned into HMG-CoA
Acetoacetyl-CoA
Acetyl-CoA
Acetoacetate
Where are primary bile salts made
Liver
Where are secondary bile salts made
Intestine
What causes the creation of secondary bile salts
Bacterial enzymes that act on primary bile salts
What two amino acids are used as bases in primary bile salts
Glycerol
Taurine
What enzyme of FA synthesis makes acetyl CoA (can also be used to make cholesterol)
Citrate lyase
What stimulates HMG CoA
Concentration of Sterol
What happens to HMG CoA when there is a low concentration of sterols
Increased cholesterol synthesis
What happens to HMG CoA when there is a high concentration of Sterols
Down regulation of cholesterol synthesis
What effect does AMP-kinase have on HMG-CoA reductase
it inhibits it
What hormones upregulate HMG-CoA reductase
Insulin
Thyroxine
What homones down regulate HMG-CoA
Glucagon
Glucocorticoids
What are competitive inhibitors of HMG-CoA
Statins
What are the “ingredients” for cholesterol synthesis
Acetyl CoA
NADPH
ATP
What do bile salts end in (Naming convention)
Cholic Acid, Cholate
What stimulates cholesterol synthesis
ATP, NADPH, Insulin, Fructose
What inhibits Cholesterol synthesis
ADP, AMP, NADP, Glucagon
