Flashcards in Glycogen, Lysosomes, FA, Lipids Deck (67)
Describe the process of FA synthesis...location, shuttle, enzymes, cofactors
Citrate from Mt matrix leaves via the citrate shuttle to the cell cytoplasm to make Acetyl-CoA via ATP citrate lyase =>
Biotin & CO2 are added to make Malonyl-CoA =>
FA synthesis is now done w/ Palmitate (16C FA)
Describe the process of FA degradation...location, shuttle, enzymes, cofactors. What will block this pathway?
FA & CoA via FA-CoA synthetase makes Acyl-CoA =>
Acyl-CoA will go from cytoplasm through the carnitine shuttle unchanged into the Mt matrix =>
Acyl-CoA is then Beta-oxidized (broken down into acetyl-CoA groups) =>
Ketone bodies are formed & TCA can start
Malonyl-CoA can block Acyl-CoA from entering carnitine shuttle & trapping it in cytoplasm
Where are FA & AA metabolized and into what?
in liver, they are metabolized into acetoacetate & Beta-hydroxybutyrate (to be used in muscle & brain)
What can cause the production of ketone bodies? How?
prolonged starvation & DKA cause OAA to deplete for gluconeogenesis;
Alcoholism has excess NADH so OAA is shunted to malate;
Both cause buildup of Acetyl-CoA so glucose & FFA production is halted & ketone bodies are produced
How will a person undergoing ketone production present? What will not be present?
Breath smells fruity due to acetone
Urine test for ketones does NOT detect Beta-hydroxybutyrate
What are the metabolic processes after a meal (fed state)?
Glycolysis & aerobic respiration;
Insulin stimulates storage of lipids, proteins, glycogen
What are the metabolic processes between meals (fasting)?
hepatic glycogenolysis (major);
hepatic gluconeogenesis, adipose release of FFA (minor)
Glucagon, Epi stimulate use of fuel reserves
In the starvation state of 1-3 days, how is blood glucose maintained?
Adipose release of FFA;
muscle & liver which shift fuel use from glucose to FFA;
hepatic gluconeogenesis from peripheral tissue lactate & alanine & from adipose tissue glycerol & propionyl-CoA
What is the only triacylglycerol component that contributes to gluconeogenesis?
propionyl-CoA (from odd chain FFA)
During starvation, how long does it take glycogen reserves to be depleted?
Starvation after 3 days leads to what source of energy being used? What is key for this source?
Adipose stores are used & ketones are primary source for brain;
Once depleted, protein degradation accelerates leading to organ failure & death (amount of stores determine survival)
What is the rate limiting step in cholesterol synthesis? How does it work? what induced it?
HMG-CoA reductase (induced by insulin) converts HMG-CoA to mevalonate
A majority of plasma cholesterol is esterified by what?
Lecithin-cholesterol acyltransferase (LCAT)
What is the MOA of statins?
competitively & reversible inhibit HMG-CoA reductase
role of Pancreatic lipase
degradation of dietary triglycerides (TG) in small intestine.
role of lipoprotein lipase
degradation of TG circulating in chylomicrons and VLDLs. Found on vascular endothelial surface
role of Hepatic TG lipase (HL)
degradation of TG remaining in IDL.
role of hormone sensitive lipase
degradation of TG stored in adipocytes.
role of Cholesterol ester transfer protein (CETP)—
mediates transfer of cholesterol esters to other
lipoprotein particles (VLDL, IDL, LDL
What are the major apolipoproteins? function?
E => mediates remnant uptake
A-1 => activates LCAT
C-2=> lipoprotein lipase cofactor
B-48 => mediates chylomicron secretion
B-100=> binds LDL receptor
What apolipoproteins function with chylomicron?
What apolipoproteins function with chylomicron remnant?
What apolipoproteins function with VLDL?
What apolipoproteins function with IDL?
What apolipoproteins function with LDL?
What apolipoproteins function with HDL?
What are lipoproteins made of? What are the primary carriers of cholesterol?
cholesterol, TGs, phospholipids;
LDL transports cholesterol from liver to tissues;
HDL transports cholesterol from periphery to liver
What is the role of the chylomicron?
Delivers dietary TGs to peripheral tissue;
Delivers cholesterol to liver in the form of chylomicron remnants, which are mostly depleted of their triacylglycerols;
Secreted by intestinal epithelial cells.
What is the role of VLDL?
Delivers hepatic TGs to peripheral tissue.
Secreted by liver.