Cholesterol Synthesis Flashcards
What is cholesterol located between
Membrane fatty acid chains
What does cholesterol form
Loose cross links and reduce fluidity
By forming loose cross links and reducing fluidity what is increased
Increases rigidity if cholesterol is next to a saturated LCFA
Where is cholesterol the highest in
Plasma membranes and is virtually absent from inner mitochondrial membranes
What is cholesterol a precursor to
Bile salts
Steroid hormones
esterfied LCFA attached to hydroxyl group and only 30% occurs in the free form
Esterfied cholesterol
Esterfied cholesterol form
Hydrophobic
Where is esterfied cholesterol not located
Membranes
What’s esterfied cholesterol transported by
Lipoproteins
What is solubilized in bile
Esterfied cholesterol
By bile salts and phospholipids
Any common organic molecule produced by combing an acid with an alcohol
Ester
Cholesterol primary site
Liver
Extrahepatic tissues:
Intestine adrenal cortex reproductive tissues
Cholesterol location
Cytosol
Some enzymes are bound to the ER
What are the raw materials
Carbon atoms: Acetyl CoA
Reducing power: NADPH
Energy: ATP Thioester cleavage
Carbs proteins and fat to Acetyl CoA to?
Cholesterol
Synthesis of Mevalonic Acid: 3 hydroxy 3 methyglutsryl CoA
HMG CoA NEEDS NADPH AND ATP
What is the rate limiting enzyme
HMG CoA reductase
HMG CoA reductase reactions occurs in the
Cytosol
What is cholesterol a essential component of
Cell membranes
what enzyme creates mevalonate
HMG CoA Reductase
what is the first unique compound in cholesterol?
mevalonate
what is irresversible
HMG CoA Reductase
Regulation is active when
non phosphorylates
regulation is inactive when
phosphorylated
squalene is originally in what type of shape
in a straight line and needs to get to a ring structure
where are the primary bile acids made
in the liver and secreted into the duodenum
where are the secondary bile acids made
in the intestine and bacterial enzymes act on the primary bile salts
bile salts/acids are secreted as
cholesterol
bile acids/salts are both
polar and nonpolar and emulsified in the intestine
bile acids/ salts are what kind of steroid nucleus
saturated steroid nucleus
what is the difference?
the number and position of the hydroxyl groups
all hydroxyl groups have an alpha configuration
what happens at the physiological ph
they ionize and occur as sodium and potassium salts
name the primary bile salts
glycocholic
taurocholic
glycochenodeoxycholic
taurochenodeoxycholic
name the secondary bile salts
deoxycholic
lithocholic
what is the precursor for all steroid hormones
pregnenolone
eat carbs muscle and liver are full of energy and glycogen glucokinase pushes glycolysis forward to liver prep step runs starts the krebs citrate is kicked out citrate lyase gives back the acetyl CoA makes fat and cholesterol
cholesterol story
sterol dependent
low sterol levels stimulate HMG COA reductase increased synthesis
sterol dependent
high sterol levels in the cell down regulates cholesterol synthesis
sterol accelerated
degradation of HMG COA reductase
sterol independent
AMP activated protein kinase (activated by CAMP)
reductase phosphorylated- inhibited
hormonal regulation stimulation
thyroxine and insulin
hormonal regulation and down regulation
glucagon and glucocorticoids
statins are …to HMG COA reductase
competitive inhibitors
is there degradation of cholesterol
no
cholesterol synthesis is stimulated by
ATP
NADPH
insulin
fructose
cholesterol synthesis is inhibited by
ADP
AMP
NADP
glucagon
