Fatty Acid Synthesis Flashcards
define lipid
anything insoluble in water
what is a fatty acid?
COO- attached to a carbohydrate chain. pka is about 4.5 so always ionized in the body
where does fatty acid synthesis primarily take place?
liver
what are the essential fatty acids and why are they important?
lineolate and linolenate- cannot by synthesized b/c humans cannot introduce double bonds beyond C9. therefore we need to eat these
difference between cis and trans fatty acids
trans are not naturally occuring and have the same thermal and biological properties as a saturated fatty acid
how is most fatty acid stored?
triglyceride- glycerol molecule with 3 ester connections to carbohydrates. this is stored primarily in adipose, with over 110,000 k cal generally available
where in the cell does fatty acid synthesis occur?
cytoplasm
when does fatty acid synthesis occur?
glucose surplus
where does fatty acid oxidation occur?
liver- energy for glucneogenesis
muscle- energy for contraction
called beta oxidation because oxidation occurs at the beta carbon
where does ketogenesis occur? what is it?
occurs only in the liver and is partial oxidation of fatty acids. these products can be used as fuel for the brain
ATP-citrate lyase
takes citrate, CoA, ATP, and H20, and converts it into acetyl-CoA and oxaloacetate.
occurs in the cytoplasm and requires ATP
Acetyl-CoA Carboxylase (ACC)
takes acetyl-CoA, ATP, and HCO3 and converts it into malonyl-CoA
requires ATP
rate limiting step
2 isozymes- alpha- liver, mammary glands
beta- muscle, liver
requires biotin (vitamin derived)
regulated by phosphorylation and via insulin/glucagon
Fatty Acid Synthase
condenses acetyl Coa and malonyl CoA thru 7 cycles of 2 carbon addition (the malonyl CoA is added to a growing chain)
forms double bonds that require NADPH for reduction
is only expressed in lipogenic tissues
requires pantothenic acid (vitamin derived)
Malic Enzyme
expressed only in lipogenic tissues, links fatty acid synthesis to NADPH synthesis
following construction of fatty acids, they are incorporated into more complex structures (eg triglycerides, phospholipids, etc.), which then get packaged into very low density lipoproteins VLDL for transport
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