module 10- lipid synthesis Flashcards
what is a precursor of storage lipids & membrane lipids
phosphatidate
how many stages is cholesterol synthesized from acetyl CoA in?
4
T or F: cholesterol synthesis is tightly regulated at several levels
T
what is a precursor of steroid hormones?
cholesterol
triacylglycerol vs phospholipid structure
T- 3 FA linked to glycerol backbone
P- 2 FA & 1 phosphate group linked to glycerol backbone
what is a common precursor for lipids
glycerol 3-P
how can glycerol 3-P derived
adipose tissue or DHAP
where does TAG vs phospholipid synthesis occur
TAG- liver & adipose tissue
P- all cells bc they are major component of membranes
phosphatidate
TAG & phospholipid precursor
triacylglycerol synthetase complex
ER membrane, catalyzes triacylglycerol synthesis from phosphatidate
T or F: CoA derivative of FA serves as activated substrate
T
where does triacylglycerol synthesis get used?
muscle or adipose tissue
phospholipids are ( ) molecules
amphiphilic- have both polar & non-polar region
where does phospholipid synthesis occur
ER
what must be linked to the phosphatidate for phospholipid synthesis
alcohol
how is CDP activated in yeast/bacteria?
linking diaclyglycerol to a CDP molecule
how is CDP activated in mammals?
alcohol is activated by linking it to CDP
what is the most abundant phospholipid
phsophotidylcholine
SAM
methyl donor for phospotidylcholine synthesis if choline is low
why is cholesterol important? (2)
1) critical component of cell membranes that ensures it has proper fluidity
2) precursor for steroid hormones- estrogen, progesterone, testosterone, cortisol, bile salts, vitaminD
T or F: all 27 carbons in cholesterol are derived from acetyl CoA
T
where does cholesterol synthesis occur?
cytosol & ER
2 characteristics of cholesterol
non-polar & insoluble in water
what does the 1st stage of cholesterol synthesis produce
mevalonate from 3 acetyl CoA
HMG-CoA reductase
regulation enzyme in cholesterol synthesis
what is the primary factor which regulates cholesterol synthesis?
intracellular concentration of cholesterol- regulates transcription gene coding doe HMG-CoA reductase
what is HMG-CoA reductase inhibited by?
high cholesterol levels
high cholesterol concentrations ( ) degradation rate
speed up
cholesterol synthesis is ( ) when energy state of the cell is low
slowed
how does “statin” work
act as competitive inhibitors of HMG-CoA reductase
lovastatin has portion that resembles ( )
mevalonate
lipoproteins
carry non-polar lipids throughout the cell
where are chylomicrons formed
small intestine
where do chylomicrons carry lipids to
adipose tissue & liver
TAG & cholesterol is packed into what kind of lipoproteins? what occurs?
VLDLs, get hydrolyzed & releases free FA acids
what lipoprotein type is main transport vehicle for cholesterol
LDLs
T or F: there is very free cholesterol on LDLs
T
what type of cells do LDL deliver to?
peripheral cells
familial hypercholesterolemia
genetic, high LDL = heart disease risk
HDL role
picks up excess cholesterol & brings back to liver
mineralcorticoids
steroids that act on kidney to regulate blood pressure & salt balance
glucocorticoids
regulate metabolic pathways & inhibit inflammation
what does hydrolyzation & cleavage of steroid hormone side chains do?
increase hydrophilic nature = better transport in blood
anabolic hormones are all based on the structure of ( )
testosterone
2 different activities of testosterone
anabolic activity for lean muscle mass & androgenic activity for male development
steroid design
enhance anabolic activity & reduce androgenic activity
