Lipid Metabolism (In Class)- Agbas Flashcards
what does citrate do in synthesis of acetyl CoA?
supplies carbons for FA synthesis
what is the primary source of fatty acid synthesis?
liver
what is the first phase of fatty acid synthesis?
cytosolic entry of acetyl CoA
what is the second phase of fatty acid synthesis?
conversion of acetyl CoA to Malonyl CoA
what are the 2 parts of the third phase of fatty acid synthesis?
elongation and desaturation
what is the rate limiting step in fatty acid synthesis?
acetyl CoA to malonyl CoA conversion
malonyl coA is important because?
it’s substrate for FA synthesis, regulates FA synthesis and is an immediate donor of the 2C units
how are fatty acid synthesized?
2Cs added at a time
what are the 3 goals achieved during phase 3?
condensation, reduction, and palmitate release
where is palmitate elongated?
in the smooth ER
what is required for desaturation?
NADPH and O2
where are double bonds put in during desaturation?
4, 5, 6, and 9
what cannot be generated endogenously for desaturation?
10 and beyond; must be taken in dietarily
what is the source of NADPH?
malic enzyme (1), pentose phosphate pathway (2-12 NADPH)
what are the ways in which FAS can be regulated?
allosteric effect (phosphorylated sugars) and induction and/or repression at genetic level
what does a high carb/low fat diet do to FAS?
increases
high fat diet and starvation does what to FAS?
lowers FAS
how are FAs stored in adipocytes?
triacylglycerol
what is the structure of triglycerols?
3 FAs attached to glycerol backbone
what are TGs synthesized?
liver, intestinal cells, and adipose tissue
where in the cell does TG synthesis occur?
cytosol
how are FAs transported in blood?
chylomicrons
what is the common aspect of TG synthesis in the 3 tissue?
Fatty acyl coA
what are the 3 main lipases in adipocytes?
hormone-sensitive lipase, lipoprotein lipase, and mono glycerol lipase
what is the most active enzyme in fasting state?
hormone-sensitive lipase
fatty acids are transported from adipocytes to liver in blood by?
albumin
where does Beta-ox of fatty acids occur?
mito matrix in liver cells
what are the 2 phases of beta oxidation?
1) transport of FFA into mito matrix and 2) beta-oxidation of FA
CPTI is negatively regulated by?
malonyl CoA
where does activation of LCFA occur?
cytosol
what does CPTI do?
transfer of activated FA into inter membrane space of mitochondria
what is the function of CACT?
antiporter; one fatty acyl carnitine into mito matrix (for one carnitine)
function of CPT II?
transfers fatty acyl residue from fatty acyl carnitine to coA
what the 4 steps in beta-oxidation?
first oxidation, hydration, second oxidation, and thiolysis
proprionyl is the only part of a FA to be what?
glucogenic
why is proprionyl the only part of FA to be glycogenic?
the route provides precursors of oxaloaceted which is converted to glucose
unsaturated FA ungergo B-oxidation until when?
disruptive alkene is reached
when does the brain prefer ketone bodies?
when starving
when do muscles utilize ketone bodies?
in fasting to preserve glucose to use by brain
why can’t liver cells use ketone bodies?
thiophorase
why can’t RBCs utilize ketone bodies?
no organelles, specially mitochondria
why are kids more prone to ketosis than adults?
glycogen deposits low; more musculature
which amino acids are purely ketogenic?
Lys and Leu
what are the 3 major ketone bodies?
acetoacetate, b-hydroxybutyrate, acetone
