L11 Biosynthesis of lipids Flashcards
Where does fatty acids synthesis and fatty acid oxidation takes place in plants?
fatty acids synthesis: Chloroplasts
fatty acid oxidation: Glyoxysomes
Where does fatty acids synthesis and fatty acid oxidation takes place in animals?
fatty acids synthesis: Cytosol
fatty acid oxidation: Mitochondris
Where does acety-CoA production take place in animal cells?
Mitochondrias
Where does ketone body synthesis take place in animal cells?
Mitochondrias
Where does fatty acid elongation take place in animal cells?
Mitochondrias
Where does NADPH production take place in animals and plants respectively?
animal: Cytosol
plant: Chloroplasts
Is the biosynthesis of fatty acid simply the reverse of fatty acid beta-oxidation？
No
What are the two enzymes involved in the biosynthesis of fatty acid?
(1) Acetyl-CoA Carboxylase
(2) Fatty Acid Synthase
What reaction does Acetyl-CoA Carboxylase catalyzes?
the carboxylation of acetyl-CoA to produce malonyl-CoA
What is the committed metabolite for fatty acid biosynthesis in animals?
malonyl-CoA
What is the prosthetic group in Acetyl-CoA Carboxylase?
Biotin
How many attachment points for acyl chains in the Fatty Acid Synthase complex?
3
What are the 4 steps of reactions happen on the site of Fatty Acid Synthase?
condensation, reduction, dehydration, reduction
At the end of each cycle of reaction happends on the site of Fatty Acid Synthase, how many carbons are added to the growing fatty acyl chain?
2
When the fatty acyl chain has reached how many carbons after how many cycles, it is cleaced from the Acyl Carrier Protein?
When it has reached 16 carbons after 7 cycles
What is the function of Acyl Carrier Protein?
It contains a phosphopantetheine group for attachment of an acyl chain
What is the reductant in the two steps of reduction happen on the site of Fatty Acid Synthase?
NADPH
Triclosan can inhibit fatty acid synthesis, what enzyme does it specifically inhibit in bacteria?
Enoyl-ACP reductase
Which two transporters is responsible for transporting acetyl-CoA from mitochondrion to cytosol for fatty acid synthesis?
Tricarboxylate transporter and tricarboxylate transporters
What is the sourse of acetyl-CoA in the mitochondrion?
(1) Pyruvate, which is derived from glucose by lycolysis incytosol
(2) Amino acid catabolism in matrix
Thus, carbohydrates and amino acids can be used to make fatty acids
Which metabolite does Tricarboxylate transporter transport?
Citrate
Animals do not have enzymes to introduce double bonds beyond which carbon?
C9
Thus, when you see fatty acids with derta number bigger thatn 9, they are essential fatty acids for us
Where does biosynthesis of triacylglycerols take place?
In cytosol
Which metabolite inhibits entry of fatty acyl-CoA into mitochondria?
Malonyl-CoA
Glucagon can regulate fatty acid metabolism, explain how.
(1) Activates lipase in adipocyte
(2) Increases cAMP level which causes acetyl-CoA carboxylase phosphorylation, thus inhibits it
Insulin can regulate fatty acid metabolism, explain how.
Decreases cAMP level which causes acetyl-CoA carboxylase phosphorylation, thus activates it
What are the two alternative biosynthesis pathways for glycerophopholipids?
(1) Acitvation of polar head group by CTP
(2) Activation of phosphatidate
What is the backbone of glycerophospholipids?
Glycerol backbone
What is the backbone of sphingolipids?
a C-18 amino alcohol backbone (Sphinganine)
Give me two examples of eicosanoids
Prostaglandin and thromboxanes; both are potent signalling molecules
What is prostaglandin used for?
(1) Trigger pain and inflammation
(2) Regulate the release of mucin for stomach protection
What is throboxanes used for?
Blood clotting
What is the first enzyme in eicosanoid biosynthesis?
Prostaglandin H2 synthase (COX)
Which enzyme is pain killers/ anti-inflammatory drugs targeting at?
Prostaglandin H2 synthase (COX)
What are the main steps of cholesterol biosynthesis?
(1) Formation of mevalonate
(2) Formation of isoprene units
(3) Formation of squalene
(4) Formation of cholesterol
Which enzyme is the cholesterol-lowering drugs targetting at?
HMG-CoA reductase;
cholesterol-lowering drugs are structural analogs of HMG-CoA, which act as competitive inhibitor of HMG-CoA
