BB451 exam 2 - Biosynthesis of Membrane Lipids

Question 1

to move lipids…

Answer 1

have to package them up to move in aqueous environment

Question 2

lipids packaged in ___ for movement

Answer 2

lipoprotein complexes (chylomicrons, VLDL, IDL, LDL, HDL)

Question 3

biggest lipoprotein with lowest density

Answer 3

chylomicron (bid and fluffy)

Question 4

cholesterol in body from…

Answer 4

synthesis, diet, storage/recycling

Question 5

lipid movement through intestines/digestive tract

Answer 5

bile acids and mechanical agitation of stomach

lipases

Question 6

bile acids

Answer 6

derived from cholesterol

act like detergent, solubilize fats in diet

Question 7

lipases

Answer 7

help emulsify fats for transport across intestinal wall

Question 8

after through intestinal wall…

Answer 8

(fats, fat soluble vitamins, and cholesterol) packaged into chylomicrons
-in lymph system

Question 9

chylomicrons move through lymph system to capillaries..

Answer 9

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

Question 10

in liver…

Answer 10

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)

Question 11

as VLDLs travel in blood…

Answer 11

get converted to IDL –> LDL

-chew away stuff but not cholesterol

Question 12

when break down VLDLs, release…

Answer 12

FFAs that glob together –> problems

Question 13

cholesterol into cells via

Answer 13

receptor mediated endocytosis of LDLs at target cell

Question 14

defects in liver LDL receptors …

Answer 14

leading cause of high blood cholesterol

ex: familial hypercholesterolemia (rare)

Question 15

causes of high cholesterol

Answer 15

dietary (first try for treatment), synthesis rate (statin inhibit HMG-CoA reductase), efficiency of recycling

Question 16

LDLs are ____ cholesterol

Answer 16

bad
associated with atherosclerotic plaque
-more prone to oxidation from free radicals –> immune system may attack oxidized LDLs –> form plaque (foam cells)

Question 17

HDLs are ___ cholesterol

Answer 17

good

• reducing levels of cholesterol
• reduced in smokers, increased in response to exercise

Question 18

bile salts/acids

Answer 18

made by introducing OH groups and oxidization to produce carboxyl groups
-effective detergent to solubilize lipids

Question 19

cholesterol and steroid hormones

Answer 19

precursor for pregnenolone –> steroid hormones

Question 20

estrogens

Answer 20

have benzene ring
made from androgens via aromatase
some tumors respond to estrogen… treat with aromatase inhibitor

Question 21

aromatase

Answer 21

make estrogens from androgens

Question 22

cholesterol –> vitamin D

Answer 22

one reaction requires UV light
7-dehydrocholesterol –> pre-vitamin D3 –> vitamin D3 –> calcitriol
most people deficient and don’t know it