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Lecture 33

BIOL 4350 Lecture 33: Lecture 33

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BIOL 4350
Rebecca Dunn

APRIL 10 PPT22 (8-16) LECTURE 33 - Breakdown and Buildup pathway o Reciprocally regulated ▪ Same things that activated one pathway breakdown another ▪ Makes no sense to build fatty acids from acetyl CoA and burning acetyl CoA to get ATP out of it ▪ They are regulated oppositely ▪ Key ways they are regulated is by the location of where they are occurring o Breakdown (Fatty acid degraaadation) ▪ Only in mitochondria and peroxisomes ▪ Steps • Begin with activated acyl group o Attached to a former carboxyl group which is now bound to a s in a thioester bond • Oxidize that o Create a double C=C bond • Hydrate o Introduce oxygen to carbon • Oxidize o Hydroxylated carbon to a ketone • Cleave o Generate an Acetyl group that has been freed and remaining chain o Synthesis ▪ Only in cytosol ▪ Steps • Begin oppositely in a condensation reaction instead of a cleavage reaction o Different because in order to build, you have to first activate an acetyl group through carboxylation ▪ Going to be a 3 carbon CoA called malonyl-CoA ▪ Spend ATP to carboxylate something and then you can get free energy out by decarboxylating • Reduction o Go from a keto to an alcohol • Dehydrate o Get rid of oxygen and form double bond • Reduction o Reduce double bond to a fully saturated C-C to get a fatty acid o Enzyme regulation ▪ One of the ways is allosteric molecules • Enzymes that are regulated allosterically don’t follow Micaela-Menkin mechanics • Tend to have s shaped ▪ Post translational modification • Not a good question on Friday’s quiz ▪ Compartmentalization • Of enzymes/substrates/both • Put processes in different places - Before you can begin harvesting energy from breakdown from fatty acids o You have to first activate it by joining to CoA APRIL 10 PPT22 (8-16) LECTURE 33 ▪ ATP dependent reaction • Enzyme: CoA synthetase • don’t need to memorize intermediate (adenylate) • end up with Acyl CoA and AMP • happens in cytosol • Keqs about 1 *** o You can make the reaction irreversible by cleaving the pyrophosphate to 2 monophosphates (inorganic) PPi2Pi o Make reverse reaction impossible o Have to take 2 phosphates to get back to ATP ▪ 2 endergonic reactions o products would be Acyl CoA, AMP, and free phosphate • Analogy*** o Small phase o Once you do it once, you are good to go o For glycolysis, you spend multiple steps in the investment phase ▪ Breakdown in mitochondria • In order to get into mitochondria o Activated fatty acids have to be covalently attached to carnitine instead of CoA o Carnitine acyltransferase I ▪ In the membrane of the mitochondria ▪ Swaps out CoA for carnitine on the fatty acid ▪ Once it moves across the matrix it gets reconverted back to acyl CoA • Why wasn’t carnitine attached in the first place? o No idea ▪ Beta oxidation pathway 1. Oxidation—Acyl CoA Dehydrogenase a. Product is that double bonded carbon b. Process FAD is reduced to FADH 2 2. Hydration 3. Oxid
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