Term
| how does glucagon, epinephrine or beta-corticotropin affect TGs? |
|
Definition
| any of these hormones will bind to a beta-adrenergic receptor, activate a G-protein, which will activate adenylate cyclase, which will activate a cAMP dependent PKA to phosphorylate hormone sensitive lipase. |
|
|
Term
| what happens when hormone sensitive lipase is phosphorylated? |
|
Definition
| when it is phorphorylated, it is activated. it will remove one fatty acid, (leaving DAG), then another, (leaving MAG). |
|
|
Term
| what happens to the MAG left by hormone sensitive lipase? |
|
Definition
| MAG lipase not hormone sensitive lipase has to remove the last fatty acid, leaving only glycerol |
|
|
Term
| what happens to the FAs released by actions of hormone sensitive lipase and MAG lipase? |
|
Definition
| they are released into the blood on albumin which can carry 6-8 FAs |
|
|
Term
| where are SCFA and MCFAs catabolized and/or activated? how many carbons does each have? what kind of transport do they use? |
|
Definition
| SCFAs are 2-4C molecules that diffuse through the inner and outer mitochondrial membranes to the matrix where activation and then beta oxidation occurs. MCFAs use the exact same process, but they have 4-12C. |
|
|
Term
| how many Cs are LCFA? where are they activated? where do they undergo beta oxidation? what kind of transport do they use? |
|
Definition
| LCFAs are 12-20Cs, they are activated in the cytosol, and then transported via the carnitine cycle into the matrix of the mitochondria where they undergo beta oxidation |
|
|
Term
| what is beta oxidation? what is given off in one step? |
|
Definition
| oxidation at the beta carbon of FAs, followed by cleavage of the alpha - beta bond, which gives acetyl CoA and a fatty acid CoA, (2C shorter than the original), 1 NADH and 1FADH2 |
|
|
Term
| how many Cs are VLCFAs? where are they catabolized? |
|
Definition
| >20C, they are catabolized to LCFAs in perioxisomes |
|
|
Term
| how are LCFAs activated in the cytosol? |
|
Definition
| LCFAs react with ATP to produce LCFA-AMP and PPi is given off in a rxn catalyzed by thiokinase. then LCFA CoA sythetase combines that with CoA and LCFA-CoA is produced along with AMP and 2Pi |
|
|
Term
| what happens to the activated LCFA-CoAs produced in the cytosol? |
|
Definition
| LCFA-CoA diffuses through the outer mitochondrial membrane and an integral protein called CPT-1 swaps the CoA for a carnitine |
|
|
Term
| what happens to the LCFA-carnitine after it has crossed the outer membrane? |
|
Definition
| LCFA-carnitine crosses the inner membrane, (via carnitine-acyl carnitidine translocase), and CPT-II swaps the carnitine for a CoA, and the LCFA-CoA is then ready for beta oxidation |
|
|
Term
| how is carnitine brought back across the inner membrane? |
|
Definition
| carnitine-acyl carnitidine translocase on the inner membrane brings it back, as it is an antiporter, (2 different molecules in different directions) |
|
|
Term
| what is one way that beta oxidation is regulated? |
|
Definition
| malonyl CoA, an intermediate of FA synthesis inhibits CPT-I, (carnitine palmitoyl transferase 1) |
|
|
Term
| what molecule gives more energy, glucose or palmitate? |
|
Definition
|
|
Term
| how many acetyl CoA are generated from one palmitate? what are they used for in muscle, liver? |
|
Definition
| 8, (16C/2C) in the muscle and liver they can go through the TCA cycle, in the liver they can also be made into ketone bodies. 7 CoA, NAD+, FAD+, H2O are used and 7 NADH and FADH2 are also produced |
|
|
Term
| where is the alpha carbon? |
|
Definition
| next one after the ketone next to the CoA |
|
|
Term
| where is the alpha carbon? |
|
Definition
| next one after the ketone next to the CoA |
|
|
Term
| what are the 4 main steps of beta oxidation? |
|
Definition
| dehydrogenation of the alpha and beta carbons, hydroxyl group added to the beta carbon, dehydration of said hydroxyl group, and breaking of the alpha-beta C-C bond where CoA is added beta C attached to the remaining fatty acid, and the alpha goes off with the released acetyl CoA |
|
|
Term
| what is the most error prone step of beta oxidation? |
|
Definition
| the first dehydration catalyzed by acyl-CoA dehydrogenase, (of which there are 3 types SCFA, MCFA, and LCFA). MCFA acyl-CoA dehydrogenase is the most commonly deficient |
|
|
Term
| what happens with an SCFA/MCFA/LCFA acyl-CoA dehydrogenase deficiency? |
|
Definition
| the pt cannot do beta oxidation, therefore they cannot make ketones, and thus in a starvation state, they cannot make glucose. hepatic damage also occurs due to increased ammonia. fats can also accumulate |
|
|
Term
| how can problems with SCFA/MCFA/LCFA acyl-CoA dehydrogenase deficiency be avoided? |
|
Definition
| in infants, frequent high carb feedings, avoiding fasting. carnitine tx can also help |
|
|
Term
| in biological systems, are FAs usually even or odd #ed? |
|
Definition
|
|
Term
| what happens if there is an odd #ed FA that goes through beta oxidation? |
|
Definition
| propoionyl CoA, (3C) is formed at the omega carbon. |
|
|
Term
| what is required for the conversion of propionyl CoA, (3C) to succinyl CoA, (4C)? |
|
Definition
|
|
Term
| what is zellweger syndrome? |
|
Definition
| reduction in the number of peroxisomes that can make VLCFAs to LCFAs |
|
|
Term
| what is the "back-up" plan for when beta-oxidation is not available for MCFAs? |
|
Definition
| omega-oxidation of fatty acids in the ER |
|
|
Term
| what is phytanic acid? what special process is needed for it to be oxidized? does this still happen in the mitochondria? |
|
Definition
| phytanic acid is a methylated, (branched chain), FA found in ruminants and dairy products. b/c of the methylation, the alpha C is removed as CO2, (alpha hydroxylase hydroxylates it)then alternating acetyl-CoAs and propionyl CoAs can be removed. this does still occur in the mitochondria, but only certain tissues |
|
|
Term
|
Definition
| alpha hydroxylase deficiency, phytanic acids cannot be broken down |
|
|
Term
| what happens if there is a CPTI/II deficiency? |
|
Definition
| reduced beta oxidation, reduced ketone bodies |
|
|
Term
| what happens if there is a deficiency in carnitine due to problems with synthesis, (genetic)? |
|
Definition
| systemic carnitine deficiency leads to cardiac, muscle weakness, hepatic damage |
|
|
Term
| what happens if there is a deficiency in carnitine due to problems with transport to muscle from the liver? |
|
Definition
| myopathic carnitine deficiency is a problem is at the muscular level, weakness, etc, (mild to fatal effects) |
|
|
Term
| what one cause for lipid malabsorbtion related to bile? |
|
Definition
| blockage in the bile duct, which delivers bile salts necessary for lipid digestion |
|
|
Term
| what one cause for lipid malabsorbtion related to the pancreatic duct? what is an example of this? |
|
Definition
| blockage of pancreatic duct could lead to necessary digestive enzymes/bicarbonate not making it to the small intestine. cystic fibrosis pts have this due to stick mucus which can block these ducts |
|
|
Term
| what is a sphingolipidosis? |
|
Definition
| synthesis/degradation of sphingolipids needs to be balanced, but occasionally a specific hydrolase for degration could be missing, causing them to accumulate in their site of degradation -> lysosomes. depending on the specific enzyme and sphingolipid involved different diseases can occur |
|
|
Term
|
Definition
| a sphingolipidosis caused by a deficiency in glucocerebrosidase, (autosomal recessive gene mutation). glucocerebroside is supposed to be broken down into glucose and ceramide, (a sphingolipid). GBA accumulates in macrophages, which when enlarged are called "gaucher cells" which are commonly seen in spleen, liver, and bone marrow. in the spleen gaucher cells lead to enlargement which activates RBC metabolism, causing faster breakdown of RBCs = anemia |
|
|
