Fatty Acid Synthesis

Frage	Antworten
What kind of reaction is the first reaction in fatty acid synthesis (after ACP has been added)? What is its purpose, what powers it and what size molecule is produced?	Condensation reaction and decarboxylation. It increases chain length to a 4C molecule. It is powered by decarboxylation of malonyl.
What electron carrier is used in the second reaction in fatty acid synthesis?	NADPH.
In what kind of pathways are NADPH and NADH primarly used?	NADPH - biosynthesis pathways NADH - energy yielding pathways
What kind of reaction is the third reaction in fatty acid synthesis? What is the purpose of it?	It is a dehydration reaction. It prepares the molecule for the next step.
What kind of reaction is the final reaction in fatty acid synthesis?	Reduction reaction (redox)
Why does the fatty acid synthesis pathway continue?	It continues to build up longer chain molecules.
What is the longest FA chain that can be produced from this pathway?	16 carbon chain
What are the four reactions in the fatty acid synthesis pathway?	Condensation -> reduction -> dehydration -> reducion *Opposite to B-oxidation
Which reaction is the commited, rate limiting step in fatty acid synthesis?	The first step - the reaction to convert Acetyl CoA to Malonyl CoA
What kind of reaction is the first reaction in fatty acid synthesis? Does it use ATP?	A carboxylation reaction? Yes.
What is the first regulatory point in fatty acid synthesis?	The first reaction - acetyl CoA carboxylase
How can fatty acids longer than 16C be made?	By further condensation reactions using enzymes on the SER in the cell and adding malonyl CoA to increase the chain by 2C each time.
What enzyme is used to make unsaturated fatty acids?	Desaturase enzyme
What is the maximum number of double bonds that can be produced in the body (in a fatty acid)?	9
How does the body get fatty acid chains with more than 9 double bonds? What are 2 examples?	By consuming them in our diet. Linolenic and linoleic acid.
What are eicosanoid hormones?	They are hormones derived from long chain FAs
What are the two ways in which acetyl CoA Carboxylase is regulated?	Allosteric mechanism and covalent modification via phosphorylation.
What is the result of phosphorylating the enzyme acetyl CoA Carboxylase? Does this reaction require ATP?	It causes the enzyme to switch off completely and prevents fatty acid synthesis. It does require ATP.
Give an example of an eicosanoid hormone and what is it derived from.	Arachidonic acid - derived from linolenic acid
How is acetyl CoA carboxylase regulated allosterically?	Allosteric regulation occurs when citrate binds to the phosphorylated form of the enzyme. It causes the enzyme to partially reactivate.
Why does allosteric binding of citrate cause partial reactivation of the enzyme acetyl CoA carboxylase?	Because lots of citrate indicates that the cell has lots of building blocks and precursors form the TCA. Therefore breakdown of fatty acids for energy is not required?
What is the purpose of arachidonic acid?	To provide building blocks for various other molecules such as prostglandins, thromboxanes.
Aspirin inhibits the production of various molecules from arachidonic acid. Which of the following does it NOT inhibit: prostaglandins, thromboxanes, prostacyclin, leukotines?	Leukotines
True or false: all substrates in fatty acid synthesis are bound to ACP?	True.
What does ACP stand for?	Acyl carrier protein. (similar to CoA and functions in the same way).
What is fatty acid synthase? Where in the cell can it be found?	Fatty acid synthase is one big molecule containing all the enzymes involved in fatty acid synthesis on one polypeptide chain. it is located in the cytoplasm.

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