Fatty acids and Membrane phospholipids biosynthesis Flashcards
seeing as the carbons from an acetyl-coA are the ones used to elongate a fatty acid, what brings the acetyl into the cytosol?
the tricarboxylate transport system
the initiation of fatty acid synthesis takes place by?
the carboxylation of acetyl-coA to generate malonyl-coA
fatty acid synthesis carries out ? rxns at a time. It lengthens a fatty acid ? carbons at a time
7, 2
elongation and desaturation of Free fatty acids requires which enzymes?
elongases and desaturases
triacylglycerol are synthesized from ?
glycerol and fatty acids
fatty acid oxidation occurs where? Has which carrier group? Has what as an electron acceptor?
in the mitochondria. CoA as a carrier. FAD, NAD+ as acceptors.
what is the tricarboxylate transport system?
is it a citrate-malate-pyruvate shuttle. That provides cytosolic Acetyl -CoA and NADPH for fatty acid synthesis
what at the 3 sources of acetyl-coA
amino acid degradation (makes cytosolic). Fatty acid oxidation (makes mitochondrial). Glycolysis (cytosolic pyruvate) which is converted to acetyl-coA in mitochondria
how does the mitochondrial acetyl-coA enter the cytosol?
as citrate
How is citrate converted into pyruvate?
citrate + ATP citrate lyase = Oxaloacetate. +malate dehydrogenase = malate. + Malic enzyme = pyruvate
what is the Acetyl- carboxylase reaction?
It needs an ATP, a bicoarbonate ion, a Biotin enzyme
ATP is hydrolysed, the energy released form here is used to transfer the CO2 from bicarbonate to biotin.
This CO2 is then moved to acetyl-coA .
and this has formed malonyl-coA
acetyl-coA carboxylase, is inhibited by, and is activated by?
it is activated by citrate.
it is inhibited from long chain fatty acid
malonyl-coA inhibits
carnitine palmitoyl transferase I, which is a mitochondrial enzyme
explain the ACC hormones control. PKA
PKA senses CMP levels (controlled by glucagon levels). It can phosphorylate the carboxylase making it less sensitive to allosteric control
explain the ACC hormones control. AMP dependant kinase?
senses ATP/ADP levels in cells. Can phosphorylate carboxylate making it less sensitive