Fatty Acid Synthesis Flashcards
Site of action of pancreatic lipase? Hormone sensitive? Lipoprotein lipase? Hepatic?
Lumen of digestive tract
Cytoplasm adiposite
Endothelial surface capillaries(by epinephrine)
Hepatocyte surface
Process of triglyceride transport and absorption?
Emulsified by bile, digested to fatty acids and 2-acyl glycerol. Reassembled into triglycerides in intestine, transported in lymph as chylomicron
How are triglycerides reassembled in the gut?
Convert FFA to CoA and attached to glycerol
How are short and medium chain fatty acids transported in blood and through portal?
Attached to serum albumin
Where does glycerol come from for triglyceride storage?
From glycerol 3p from DHAP in glycolysis
How does insulin affect fat storage?
Stimulates glycolysis and FFA synthesis (via Acetyl CoA Carboxylase). Inhibits fat mobilization (hormone sensitive lipase)
What is the rate limiting enzyme in fat synthesis and protein what does it do?
Acetyl CoA Carboxylase. Attaches CO2 to Acetyl CoA with biotin and ATP.
Is AMPK a starvation signal?
Yes. Promotes ATP production
How is Acetyl CoA Carboxylase regulated?
Inhibited by product palmitoyl CoA, stimulated by citrate. Inactivated by AMPK, stimulated by insulin
How does glucagon act on Acetyl CoA Carboxylase?
Uses AMPK to phosphorylate and inactivate it. Indicates fuel mobilization
How is initiation of fatty acid synthesis begun?
Acetyl CoA and malonyl CoA attach to fatty acid synthase. Pantothenic acid is cofactor.
What is the cofactor for reduction of 3 ketoacyl group on elongating chain?
NADPH
Elongation steps of fatty acid synthesis?
ACP binds malonyl CoA, and Acetyl CoA attaches to it. Reduced by NADPH, moved to KA site and repeat.
How long is fatty acid chain when thiolase terminates it?
16C
How is Acetyl CoA moves from mitochondria to cytoplasm?
Carried on citrate and converted to Acetyl CoA and oxaloacetate
How does OAA return to mitochondria?
Changed to malate and transported in. Malate dehydrogenase on both sides, uses NADH
What cofactor does malic enzyme use?
NAD+
Where does the carbon come from for fatty acids?
Glucose or fructose made into Acetyl CoA
What is the product of fatty acid synthase, and how long is it?
Palmitate. 16 c. Can be extended into stearate in ER.
How are unsaturated fatty acids made?
Desaturates add double bonds up to 9c limit. Any after is necessary in diet.
Desaturation of palmitate produces what? Stearate?
Palmitoleic acid. Oleic acid
What is precursor of arachidonate and what is arachidonate?
Linoleic acid. Inflammatory signal
How do long chain fatty acids get in blood?
Via the lymph. Travel in chylomicrons. Short and medium go through liver first
Where does pancreatic lipase work on triglycerides?
1 and three carbons. Leave one acyl behind to prevent glycerol from fleeing
