How many molecules of acetyl CoA are produced by catabolism...

How many molecules of acetyl CoA are produced by catabolism of the following fatty acids, and how many passages of the $\beta$ -oxidation pathway are needed? (a) Palmitic acid, $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{14} \mathrm{CO}_{2} \mathrm{H}$ (b) Arachidic acid, $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{18} \mathrm{CO}_{2} \mathrm{H}$

How many molecules of acetyl CoA are produced by catabolism of the following fatty acids, and how many passages of the $\beta$ -oxidation pathway are needed?
(a) Palmitic acid, $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{14} \mathrm{CO}_{2} \mathrm{H}$
(b) Arachidic acid, $\mathrm{CH}_{3}\left(\mathrm{CH}_{2}\right)_{18} \mathrm{CO}_{2} \mathrm{H}$

Key Concepts

Fatty Acid Catabolism

This concept involves the breakdown of fatty acids through a series of biochemical reactions to ultimately produce energy. In eukaryotic cells, fatty acids are primarily catabolized in the mitochondria, where they are converted into smaller fragments that can feed into energy-producing pathways such as the citric acid cycle.

?-Oxidation Pathway

?-Oxidation is the metabolic process by which fatty acids are broken down in the mitochondria. This cyclic process involves four main steps: oxidation, hydration, a second oxidation, and thiolysis. With each cycle, two carbon units are cleaved from the fatty acid chain, forming acetyl CoA, and the shortened fatty acid undergoes another round of oxidation until it is completely broken down.

Acetyl CoA

Acetyl CoA is a central metabolic intermediate that plays a crucial role in energy production. Produced during the ?-oxidation of fatty acids, acetyl CoA enters the citric acid cycle, where it is oxidized to produce ATP, carbon dioxide, and high-energy electron carriers that feed into the electron transport chain.

Calculation of ?-Oxidation Cycles

In the catabolism of fatty acids, the number of ?-oxidation cycles and the number of acetyl CoA molecules produced can be determined by the chain length. For a fatty acid with an even number of carbons (n), the complete breakdown yields n/2 molecules of acetyl CoA. Since each cycle removes two carbon units until the final acetyl CoA is formed, the number of cycles required is (n/2 - 1).

Transcript

00:01 Just kind of remember that this beta oxidation process is occurring in the mitochondria, producing organelle, energy -producing organelle of the cell.

00:13 Before we do kind of these longer lipids, this takes something a little bit simpler, just to understand the beta -oxidation process.

00:22 So we'll take something much simpler.

00:24 This is called butyric acids.

00:25 Just got four carbons with a carbonyl at the end.

00:31 And just to remind myself, i'm going to put a methyl or ch3 group here at the end.

00:38 Now, the target for beta oxidation is this part, is this, it's going to be alpha, this is beta carbon.

00:49 That's why it's called the beta oxidation part.

00:51 This would be the alpha carb.

00:52 This is the carbonene.

00:54 This is the alpha carbon, and this is the beta carbon.

00:58 And the reason that's the target is because in the next step of the process, after it's been target identified, what's going to happen is it is going to put or insert a ketone, not keep a carbonyl right on it.

01:21 That's the alpha.

01:22 I'm sorry.

01:25 There we go.

01:28 Right here.

01:31 Let's fix that.

01:33 Again, this still being alpha, this still being beta.

01:38 Alright, then the next step is just going to cleave it or cut it.

01:46 And the result being we're going to have two different, let's see, little coa molecules.

01:53 And at that point, that's where the reaction stops.

01:56 As long as you get those two out of the way, then that's pretty much it.

02:04 So that's a simple way of looking at.

02:07 Let me finish this.