Fatty Acid Synthesis

where are fatty acids further elongated and desaturated?

ER->synthesis of polyunsaturates

fatty acid synthesis requires which cofactor? where does it come from?

-each citrate molecule generates 1 through the malice enzyme reaction and the rest come from TCA cycle and pentose phosphate shunt.

what are the benefits of converting dietary carbs into fat?

-greater energy density in triglycerides, oxidation yields higher amount of energy -lipids are also poorly soluble>packed tightly>cuts down huge amount of weight because don't need water!

glycemic index?

speed of conversion of carbohydrate to fat -high means breakdown into glucose fast low-slow

what are the two major initiators of fatty acid synthesis?

Citrate (carbon source) and NADH (remember this because cytosol is a reducing environment!)

fatty acid synthesis:explain: Condensation Reduction Repeat

Condensation: loss of CO2 when elongate chain (this was added onto acetyl coA forming malonylCoA) Reduction: by NADPH + H+ Repeat cycle until have enough Cs

glycerol kinase is located where? what does this enzyme do?

LIVER only glycerol to glycerol-3-Phosphate to enter pathway to become triacylglycerol - that gets packed into VLDL and released in blood

carbon source for fatty acids?

citrate

what does storage of glucagon require? why is this not ideal?

WATER..HEAVY

what common way do Liver and Adipose tissue form fat? what state?

Fed state glycolysis proceeds and get DHAP which can be reduced by NADH to get glycerol-3-phosphate and proceed to make tiacylglycerol (liver packs it as VLDL that is released into blood and adipose stores it as fat)

where does VLDL go once released into blood? what state does this happen?

Fed state, liver turns glucose into fat -some ends up in muscle where fatty acids diffuse -most ends up contributing to adipose tissue -goes to TG which has to be broke down by enzyme LPL (lipoprotein lipase) that allows entry of FA into adipose tissue and release of glycerol that goes to liver

malonyl CoA

It plays a key role in chain elongation in fatty acid biosynthesis

which enzyme is a key regulatory step in fatty acid synthesis? how is it regulated? (inactivated vs. activated) -what is its job? what does it use?

acetyl CoA carboxylase *Activated by insulin->phosphatase (dephosphorylation) and citrate *Inactivated by protein kinase (phosphorylation, cAMP), palmitoyl CoA,glucagon/fasted state, epinephrine converts Acetyl CoA into malonyl CoA (uses CO2, biotin, ATP)

synthesis of fat from carbohydrate requires? product? name of this process?

acetyl coA subunits + NADPH + H fat + (NADP+) + ADP + P + CoASH lipogenesis

which two enzyme are highly involved in fatty acid synthesis?

acetyl-CoA carboxylase fatty acid synthase

when you eat a high carb diet is fatty acid synthesis activated or inhibited?

activated

where do fatty acids get elongated and destaturated?

atty acid can be elongated or desaturated (adding double bonds) by enzymes in the ER

is acetyl CoA carboxylase regulated via modulation of enzyme activity, enzyme synthesis or both?

both

cytosolic malate dehydrogenase -what does it use?

converts OAA into malate (opposite of whats going on in TCA) uses NADH !!!

malic enzyme -what does it use

converts malate into pyruvate -uses NADP+

is fatty acid synthetase regulated via modulation of enzyme activity, enzyme synthesis or both?

enzyme synthesis

citrate lyase -what does it use?

enzyme that splits covalent bonds between C's, 6C breaks down into OAA and acetyl CoA at expense of ATP hydrolysis

fatty acid synthase

enzyme where chain synthesis occurs: malonyl CoA attaches P site and then chain that is attached to CYSTEINE residue of fatty acid synthase transfers over to new malonyl CoA

In fed state, what is the main destination of fatty acids?

fatty acids produce fat (triglycerides/triacylglycerols) in adipose tissue

what structural components for the cell membrane can fatty acids produce?

glycerolphospholipids and sphingolipids

Lipoprotein lipase (LPL) is located where? function?

in the capillaries of adipose tissue, muscle, and the lactating mammary gland, digest the triacylglycerol of VLDL, forming fatty acids and glycerol. fatty acids go into adipose tissue and glycerol goes to liver which can be cycled back through

when you eat a high fat low carb diet is fatty acid synthesis activated or inhibited?

inhibited

Where does fatty acid synthesis occur? what are they synthesized from?

mainly in the liver, primarily from glucose: allows dietary carbs to form fat

what is acetyl CoA converted into for fatty acid synthesis? -what is required for this reaction?

malonyl CoA CO2, biotin, acetyl CoA carboxylase, ATP

what happens after activation of palmitic acid?

palmitoyl-CoA=activated the fatty acid can be elongated or desaturated (adding double bonds) by enzymes in the ER

pyruvate carboxylase

pyruvate into OAA

pyruvate dehydrogenase

pyruvate into acetyl CoA