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50 Cards in this Set
- Front
- Back
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Define a lipid |
multiple hydrocarbon groups and a few oxygen or polar groups. insoluble in water, soluble un nonpolar organic solvents |
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why are lipids important |
storage of energy membrane structure hormone and signalling compunds |
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most common type of lipid |
complex lipid |
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complex lipid |
two or more smaller compounds put together but the main component is the fatty acids |
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most common fatty acid |
C16 |
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phospholipids |
contains a phosphate group |
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fatty acid chain length |
significant effect on the extent of interchain interaction longer chains have more interaction |
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Ampithatic molecules |
molecules, which when added to water form a monolayer with hydrophobic hydrocarbon chains projecting from water. shaking produced micelles vigorous shaking of bilayers produces liposomes |
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where do fatty acids come from? |
30/40%-diet adipose (fat storage cells) de novo synthesis |
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liver |
produces bile which contains bile salts and acids act as detergents emulsifying the lipid and forming a small droplet of fat |
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pancreas |
produces digestive enzymes and H2Co3- |
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summary of series of events in fatty acid metabolism |
lipid micelles monoglyceride + fatty acid transport into ER formation of chylomicrons chylomicrons in lymphatic vessel |
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pancreatic lipases |
triacylglycerol lipase catalyses the hydrolysis of triacylglycerols at the 1 & 3 positions |
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triacylglycerol lipase |
works best in aqueous solution produced from excretion from the pancreas FA and 2 acylglyercol molecules able to diffuse through the epithelial wall of the intestine |
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Phosophotase A2 |
acts on phospholipids to aid digestion by removing the FA residue from position C2 to form lysophospholipid + FA |
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transport of lipids |
lipoprotein complexes are used complexes are classified by density |
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protein in capillary endothelium |
lipoprotein lipase interacts with lipoproteins and breakdowns triacylglycerol able to breakdown triacylglycerol products of this breakdown diffuse out of chylomicrons and into cells of the tissue |
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chylomicrons |
return in the blood to the liver to be processed to VLDL activate lipoprotein lipase and release fatty acids to tissues once inside tissues FAs metabolised to provide energy to the cells |
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odd/ even chain fatty acid products |
odd chain- ALWAYS benzoate even chain- ALWAYS phenyl acetate |
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3 stages of beta oxidation |
activation transport oxidation |
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stage 1 of beta oxidation: activation |
the addition of CoA to form acyl-CoA occurs on the outer surface of the mitochondria catalysed by Acyl-CoA synthase reactio driven to the right by removal of product pyrophosphotase |
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stage 2 of beta oxidation: transportation of products into the mitochondria |
specifically the matrix inner membrane is hard to diffuse through need an active transport system fatty acid component is removed and transferred to carnitine once inside the matrix, carnitine releases fatty acid molecule to an acyl group |
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carnitine transferase I |
selective for different types of fatty acid -length -saturation OH group on carnitine molecule is where the acyl group is attached and releases CoA |
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stage 3 of beta oxidation: oxidation |
occurs inside the matrix 2C unit is removed via a 4 step process process is repeated as long as FA is still 4 C long attacks the 3rd (beta) C |
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step 1 of oxidation |
oxidation of palmitoyl CoA acyl-CoA dehydrogenase removal of two H FAD accepts to form FADH2 final product is trans delta 2 enoyl CoA |
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step 2 of oxidation |
hydration of trans delta 2 enoyl CoA is hydrated by enoyl CoA hydralase forms 3 L beta hydroxylacyl CoA |
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step 3 of oxidation |
oxidation of L beta hydroxyacyl CoA NAD+ -> NADH beta ketoacyl CoA |
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step 4 of oxidation |
thiolytic cleavage of beta ketoacyl CoA acyl CoA acetyltransferase (thiolase) CoA-SH is added to the molecule produces acyl CoA and acetyl CoA |
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the overall reaction of beta oxidation of FAs |
Cn-Acyl-CoA + FAD + NAD+ + H2O + CoA -> Cn-2-Acyl-CoA + FADH2 + NADH + H |
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what happens to acetyl CoA when it is produced? |
most is sent to CAC some is made into ketone bodies |
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what are the main products of beta oxidation? |
FADH2 NADH H2 |
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conversion of products into ATP |
1 GTP = 1 ATP 1 NAD = theory 3, actual 2.5 1 FADH2 = theory 2, actual 1.5 |
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ATP production from palmitoyl CoA |
theory = 131 actual = 108 |
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yield per carbon oxidised to CO2 |
#ATP/#C |
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ketone bodies |
oxaloacetate is needed for entry of acetyl CoA into TCA cycle ketone bodies are not always present in high enough concentrations |
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how does the liver deal with excess Acetyl-CoA |
by making ketone bodies ketone bodies are -energy rich -water soluble |
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HMG- CoA lyase |
key liver enzyme removes an acetyl CoA to form acetoacetate |
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components of complex lipids |
triacylglcyerols principle components of cell membranes signalling molecule |
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naturally occuring amino acids |
are even chained most common is C 16:0 (palmitic acid) |
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where does synthesis of fatty acids occur? |
the cytosol |
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requirements of FA synthesis |
NADP+/NADPH CO2 in the form of HCO3- |
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two products of homogenesis of tissue |
pellet -nuclear material -mitochondrial fragments -all membranous debris soluble fraction -no membrane fractions -only soluble proteins |
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stage 1 of FA synthesis |
two step process where the intermediate is not released irreversible stage carboxylation of acetyl CoA to form malonyl CoA requires biotin and ATP two enzymes involved -biotin carboxylase -malonyl CoA |
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stage 2 of FA synthesis |
chain elongation successive C2 addtions by FA synthatase requires ATP |
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difference between a synthase and a synthetase |
synthetases must cleave (hydrolyze) an ATP molecule to function, synthases do not require energy input provided by ATP hydrolysis |
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fatty acid synthase |
catalyses 7 separate reactions 7 active sites found in cytosol requires malonyl-CoA and acetyl-CoA requires NADH |
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enzymatic steps of FA synthesis: 1 |
acetyl-CoA attached to protein ACP (acetyl carrier protein) -acetyl transacylase -acetyl transferred to beta ketoacyl synthase domain |
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enzymatic steps of FA synthesis: 2 |
malonyl group transferred to ACP catalsysed by malonyl transacylase |
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enzymatic steps of FA synthesis: 3 |
condensation reaction catalysed by beta ketoacyl-ACP synthase CO2 is released simulatenously |
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enzymatic steps of FA synthesis: 4 |
reduction catalysed by beta keto ACP reductase NADP+ is produced |
