Test 2: Lipid and FA Metabolism Flashcards
Where are most FA synthesized?
Liver
What are the fates of fats/lipids/FA’s
energy substrates
precursors
structural elements (membranes etc…)
signaling molecules (cholesterols, leukotrienes, prostaglandins)
Describe the process of absorbing/transporting dietary lipids
bile salts emulsify the fat in small intestine to form micelles
intestinal lipases degrade TG (triacylglycerol)
FAs and other products taken up by intestinal mucosa and converted into TG
TG packed with cholesterol and apolipoproteins into chylomicrons
chylomicrons move through lymphatic and bloodstream to tissues
Lipoprotein lipases (activated by apoC-II) converts TG to FA and glycerol)
FA enters cells
FAs are oxidized as fuel or reesterified for storage
How are FAs transported?
Free FAs: carried by serum albumin
Lipoproteins: carry TG and cholesterol
What is a lipoprotein composed of?
phospholipid, cholesterol, and protein membrane-bound vesicles containing TGs
What are the four classes of lipoproteins
Chylomicrons
VLDL (very low density lipoprotein
LDL (low density lipoprotein)
HDL (high density lipoprotein)
What lipoprotein has the highest amount of protein?
HDL
What lipoprotein has the highest amount of phospholipid?
HDL
What lipoprotein has the highest amount of cholesterol?
LDL
What lipoprotein has the highest amount of cholesterol ester?
LDL
What lipoprotein has the highest amount of TG?
Chylomicron
What lipoprotein has the lowest amount of TG?
HDL
What forms when foam cells die?
They form atherosclerotic plaques
What lipoprotein do we want in high concentrations and why?
HDL’s
because they scavenge excess cholesterol and prevent foam cells from forming
Very generally, what are common functions of LDL and HDL?
transport cholesterol
Generally, what does VLDL transport and to where?
FAs to target tissues
What happens during starvation to glucagon levels and how does that affect FA
increase level of glucagon in bloodstream
mobilize FAs
describe the glucagon receptor pathway when glucagon binds its receptor/ how FAs are released into the bloodstream
Glucagon binds its receptor –> activates Adenylyl cyclase –> cyclic AMP –> activates Protein Kinase A (PKA) –> activates Hormone Sensitive Lipase (HSL) –> eventually releases FAs from the lipid droplet into the bloodstream
What are the components of TG?
3 FAs and 1 glycerol
What are the fates of the components of TG in lipid catabolism?
lipase breaks TG into glycerol and 3 FAs
glycerol is shuttled to glycolysis and generates ~5% of energy from lipid catabolism
3 FAs form acyl-CoA which is transported into M.T. (mitochondria) for oxidation via acyl-carnitine transporter (~95% of energy produced from lipid cat..)