Fatty Acid Synthesis Flashcards
define lipid
anything insoluble in water
what is a fatty acid?
COO- attahched to a carbohydrate chain, pKa is 4.5 so it is always ionized in the body.
where does fatty acid synthesis take place primarily?
liver
what are the essential fatty acids and why are they important?
lineolate and linolenate (omega 3) cannot be synthesized because humans cannot introduce double bonds beyond C9 and therefore these come from our diet
what is the difference between cis- and trans- fatty acids?
Trans are not naturally occurring and have the same thermal and biological properties as saturated fatty acids
how is most fatty acid stored?
Triglyceride: glycerol molecules with 3 ester connections to carbohydrates, this is stored primarily in adipose with over 110,000 kCal of energy available
where in the cell does fatty acid synthesis occur?
cytoplasm
when does fatty acid synthesis occur?
in times of glucose surplus
where does fatty acid oxidation occur?
FA oxidation 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 (ACL)
takes citrate, CoA, ATP, and water and converts it into acetyl-CoA and oxaloacetate, this occurs in the cytoplasm and requires ATP
Acetyl-CoA Carboxylase (ACC)
takes acetyl-CoA, ATP, and HCO3, and converts it into malonyl-CoA requiring ATP and is a rate-limiting step
There are 2 isozymes: alpha is in the liver and mammary glands, beta is in muscle and livers mitochondria
Both require biotin regulated by phosphorylation and via insulin/glucagon
Fatty Acid Synthase
condenses acetyl CoA and malonyl CoA through 7 cycles of 2 carbon additions (the malonyl CoA is added to a growing chain) forms double bonds that require NADPH for reduction and is only expressed in lipgenic tissues and requires pantothenic acid
Malic enzyme
is expressed only in lipogenic tissues, links FA synthesis to NADPH synthesis
What happens to fatty acids afer they are made? What structures are made next?
They are incorporated into more complex structures (TGs, PLs, etc.) which then get packaged into VLDLfor transport.
how is VLDL used?
transported to adipose tissue as storage
