BB451 exam 2 - Biosynthesis of Membrane Lipids Flashcards
to move lipids…
have to package them up to move in aqueous environment
lipids packaged in ___ for movement
lipoprotein complexes (chylomicrons, VLDL, IDL, LDL, HDL)
biggest lipoprotein with lowest density
chylomicron (bid and fluffy)
cholesterol in body from…
synthesis, diet, storage/recycling
lipid movement through intestines/digestive tract
bile acids and mechanical agitation of stomach
lipases
bile acids
derived from cholesterol
act like detergent, solubilize fats in diet
lipases
help emulsify fats for transport across intestinal wall
after through intestinal wall…
(fats, fat soluble vitamins, and cholesterol) packaged into chylomicrons
-in lymph system
chylomicrons move through lymph system to capillaries..
get stuck in capillaries
lipoprotein lipases: remove some fat (eat away center), don’t touch cholesterol
chylomicrons shrink –> chylomicron remnants
exit capillaries and move to liver
in liver…
chylomicron remnants taken up by liver and released as VLDLs when needed
- liver has a capacity
- liver senses body’s need for lipids via LDL receptors (if cant detect, –> release)
as VLDLs travel in blood…
get converted to IDL –> LDL
-chew away stuff but not cholesterol
when break down VLDLs, release…
FFAs that glob together –> problems
cholesterol into cells via
receptor mediated endocytosis of LDLs at target cell
defects in liver LDL receptors …
leading cause of high blood cholesterol
ex: familial hypercholesterolemia (rare)
causes of high cholesterol
dietary (first try for treatment), synthesis rate (statin inhibit HMG-CoA reductase), efficiency of recycling
LDLs are ____ cholesterol
bad
associated with atherosclerotic plaque
-more prone to oxidation from free radicals –> immune system may attack oxidized LDLs –> form plaque (foam cells)
HDLs are ___ cholesterol
good
- reducing levels of cholesterol
- reduced in smokers, increased in response to exercise
bile salts/acids
made by introducing OH groups and oxidization to produce carboxyl groups
-effective detergent to solubilize lipids
cholesterol and steroid hormones
precursor for pregnenolone –> steroid hormones
estrogens
have benzene ring
made from androgens via aromatase
some tumors respond to estrogen… treat with aromatase inhibitor
aromatase
make estrogens from androgens
cholesterol –> vitamin D
one reaction requires UV light
7-dehydrocholesterol –> pre-vitamin D3 –> vitamin D3 –> calcitriol
most people deficient and don’t know it
