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Description
Flashcards by sophiakostich, updated more than 1 year ago
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Created by sophiakostich
almost 11 years ago
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| Question | Answer |
| 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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