Fatty Acid Biosynthesis Flashcards
Overview of steps
- Acetyl-Coa in the cytoplasm
- Generating NADPH in the cytoplasm
- Conversion of Acetyl-CoA to Malonyl-CoA in the cytoplasm
- Fatty acid synthase
Why is liposynthesis important?
For fat storage during excessive nutrients
What electron donor is used and why?
NADPH, it has two which can reduce C=O to HC-OH (when generating glycerol after glycolysis)
Where are electrons taken for the electron carrier?
The malic enzyme reaction (malate to pyruvate) and the pentose-phosphate pathway during glycolysis (G-6-P to F-6-P)
What is the role of acetyl-CoA carboxylase?
Carboxylates acetyl-CoA into Malonyl-CoA
How is acetyl-CoA carboxylase regulated? (four regulators in total)
Allosterically (binds to citrate via a hydroxyl group to activate it) and by phosphorylating (it is inactive when there is a phosphate group). Both are necessary to activate the enzyme. Also, negatively regulated by palmitoyl-CoA (product) and AMP (which activates a protein kinase, and the kinase uses up 1ATP per phosphate added to acetyl-CoA carboxylase.
What is the purpose of beta-oxidation?
Converting fat into acetyl-CoA
What is done during beta-oxidation?
The link between the beta carbon and the alpha carbon on a fatty acid chain is broken, yielding acetate, which can be turned into acetyl-CoA.
How many acetyl-CoA molecules are needed to generate a single molecule of palmitic acid?
8 molecules, to yield a 16-C chain (palmitic acid).
Amount of ATP used to power generation of palmitic acid
7
Amount of water lost after generating palmitic acid
6
Amount of NADPH used to generate a molecule of palmitic acid
14
What attaches to FA synthase and how?
Via two thioesters, an acetyl CoA group and a malonyl CoA group attach. The thioesters belong to a dimer of the same kind of subunit, a thioester on each.
Product after reacting FA synthase dimer with itself
Malonyl CoA group becomes an acetyl CoA group as CO2 is released. Ultimately forming palmitic acid.
