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39 Cards in this Set
- Front
- Back
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Why are trans fatty acids bad?
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-Body can't get rid of them (enz. aren't specific for trans, only cis)
-Packs easier, has dif. properties (higher mp) |
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What is Linoleic Acid?
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-Essential FA
-Has 2 db that body can't add -C18:2 -Add 2 more C and 2 more db to et Arachidonic acid (C20:4) |
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What is ACC?
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-Acetyl-CoA Carboxylase
-Rate Limiting enz. for FA syn, -Converts Acetyl-CoA to Malonyl CoA |
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What are the activators of ACC?
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-Insulin
-Citrate |
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What are the inhibitors of ACC?
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-Glucagon
-AMP Kinase -Palmitoyl CoA |
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What is Palmitoyl CoA?
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-Product of the FA synthesis
-Temporarily inhibits ACC (till removed, so that path won't be broken down) |
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1)What acts on Palmitoyl CoA?
2)Why? 3)What does Palmitoyl CoA do? |
1) Acyl Transferase
2)To make triglycerides 3) Plays a role on integrating the regulation of B-oxid and FA synthesis (Don't want both happening at the same time) |
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How are FA stored?
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As triglycerides
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Where does FA synthesis take pace?
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Cytoplasm
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How would you control FA synthesis?
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Regulate the rate limiting enz ACC
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What is the ACP group?
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-Similar to CoA
-Acts as a temporary carrier to growing acyl chain -Attached to FAS, binds the growing acyl chain in the same way Acetyl CoA bind FA/Glycolytic paths |
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How does FA synthesis work?
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-Adds 2 C at a time
-FAS fcts as a dimer |
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What are the steps of FA synthesis?
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1) Loading of acetyl CoA and then loading of Malonyl CoA
2)Condensation 3)Reduction 4)Dehydration 5)Reduction 2 6)Elongation of Chain |
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What is step 1 of FA synthesis?
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-Charge an Acetyl-CoA onto KS (only the 1st addition is Acetyl CoA, all subsequent additions are Malonyl CoA)
-Add Malonyl CoA to ACP -MAT adds both Acetyl-CoA and Malonyl CoA -Get a 5C FA |
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What is step 2 of FA synthesis?
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-Condensation rxn
-CO2 leaves :.: of close interaction btw CoA's -Enz: KS -Get a 4C FA attached to ACP |
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What is step 3 of FA synthesis?
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-Reduction of keto gp to OH gp
-Reduce using NADPH -Involves enz KR |
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What is step 4 of FA synthesis?
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-Dehydration rxn
-Create db by removing H2O -Enz: DH |
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What is step 5 of FA synthesis?
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-Reduction #2
-reduce db using NADPH -Enz: ER |
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What is step 6 of FA synthesis?
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-Translocation of FA from ACP to KS
-This allows further addition -Enz: MT All malonyl CoAs are added on the inside, while the acetyl CoA is pushed to the hydrophobic end |
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Why does ACC add a C to Acetyl CoA to make Malonyl CoA and then right after lose the C in condensation rxn?
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1) Energetics
2)Makes rxn irreversible |
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How many cycles before you produce something? What do you make?
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After 7 cycles, you have made 16C Palmitate
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How is palmitate released? What happens next?
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-The Palmitate FA is released from ACP by TE
-Palmitate can then be elongated or desaturated |
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How is the Pentose Path involved in FA synthesis?
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Used to get the NADPH required for both reduction step of FA synthesis (Steps 3 & 5)
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Important points of FA synthesis.
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-Occurs in cytoplamsm
-ACP is main acyl-gp carrier -Use NADPH as e- donor --2C donor malonyl CoA (except for the 1st rxn) -Intermediate D-B-hydroxyacyl group |
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Stoichiometry of palmitate synthesis?
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Use total of 14NADPH and 7ATP
-will get back all the E we put in back later |
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Uses of Palmitate?
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-Desatirate to get a db
-Elongate to get other FA (add 2C and db, get Oleic Acid) |
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How do you add double bonds to FA?
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Desaturases
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Where does elongation/desaturation take place?
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Can happen in various locations, depending on the organelle
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What are the steps to mitochondrial elongation?
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1) Condensation: add 2 acetyl CoAs tog.
2) Reduction: use NADH 3) Dehydration: enz=hydratase(its reversible) 4) Reduction: NADPH |
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What are the dif btw mitochondrial elongation and FA synthesis?
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1) Mito. elongation has separate enzymes that are not all part of the same complex. FA synthesis uses FAS, which is one multifctnal enz
2) The 2 C molec come from acetyl CoA, not Malonyl CoA 3) 1st reduction in mito. uses NADH, not NADPH 4)Mito has an L-hydroxyl intermediate while FA syn. has a D-hydroxyl intermediate |
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What is the use of the citrate shuttle? (2)
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1) Transpors acetyl CoA from the mitochondria to the cytoplasm, where it can then be used for F synthesis
2)Generate NADPH, which will be used in FA synthesis |
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Why is linoleae (linoleic acid) essential?
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We need it to make arachidonic acid cuz we don't have the enz needed to desaturte (make db) in the right place to make arachidoinc acid
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Which position on FA canhumans desturate?
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delta: 9, 5 and 6
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Which positions n FA can humans not desaturate?
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delta: 12 and 15
.: can't make arachidonic acid |
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What are the different types of FA?
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-saturated short chain FA
-saturatd long chain FA -unsaturated long chain FA |
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1)What happens when you have more unsaturated FA?
2)When you have more saturated FA? |
1) more unsat: lower MP, more liquidy (i.e. olive oil=oleic acid=liquid)
2) more sat: higher mp, more solid (i.e butter, fat) |
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When Temp inc, mb fluidity inc. How do FA counteract this?
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-Inc amt of saturated long chain fats cuz they pack better and have a higher MP
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When Temp dec, mb fluidity dec. How do you counteract this?
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-Inc amt of unsat FA (or dec. amt of sat FA)
-Decrease the length of the FA |
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1)How do you increase MP?
2)How do you decrease MP? |
1) Inc length of chain, inc amt of sat'n (dec. unsat)
2)Shorter chains and inc unsat (Inc fluidity, counteract by having more saturated FA, that have longer chains and vice versa) |
