Intro to Fatty Acid Oxidation: Study with Video Lessons, Practice Problems & Examples

Fatty acid oxidation is a crucial process in food catabolism, occurring in three phases: activation, transport, and oxidation. Initially, fatty acids are activated to fatty acyl CoA using ATP. They then move to the mitochondrial matrix via the carnitine shuttle. In the final phase, beta oxidation breaks down fatty acyl CoA into multiple Acetyl CoA molecules, generating high-energy molecules NADH and FADH₂. This process is essential for ATP production and can also lead to ketone body formation, highlighting its significance in energy metabolism.

Intro to Fatty Acid Oxidation Concept 1

In this video, we're going to take a look at an introduction to fatty acid oxidation. Now, here we're going to say that fatty acid oxidation is part of stage 2 of food catabolism. We're going to say here, it oxidizes fatty acids to yield Acetyl CoA and our high-energy molecules in the form of NADH and FADH₂. If we take a look here at the overview, we have our stage 1, we're focusing on the digestion of our lipids and we're paying attention to the creation of our fatty acids. We're not paying attention to glycerol. With our fatty acids, we have fatty acid activation which utilizes ATP to do this. So we're activating our fatty acid, and this is happening within the cytosol under anaerobic respiration. From here, we would then head into stage 2, where we're dealing with the mitochondrial matrix. Here, beta oxidation occurs where we have the formation of our Acetyl CoA. Now, Acetyl CoA can have one of 2 possibilities where it can continue on to stages 34 to the eventual production of ATP or we can have the formation of what we call ketone bodies which we'll discuss later on. Now here, we're going to say fatty acids are prepared or activated for oxidation within the cytosol, as we can see in our overview. And oxidation takes place inside the mitochondrial matrix. So here we have our beta oxidation that occurs. So just remember when we talk about fatty acid oxidation, it's occurring in stage 2 of food catabolism.

Intro to Fatty Acid Oxidation Example 1

Which of the following statements is not true for fatty acid oxidation?

A, fatty acid oxidation is a catabolic process that degrades fatty acids to Acetyl CoA. This statement is true. We do have the breaking down of lipids to fatty acids, and that eventually gets broken down into Acetyl CoA. Fatty acids are activated in the cytosol, that is true, and oxidize inside the mitochondrial matrix, that is also true. Remember, we utilize ATP in order to activate our fatty acid within the cytosol and then, when we get to the mitochondrial matrix, we undergo what's called beta oxidation to form our Acetyl CoA.

High-energy molecules produced in fatty acid oxidation are FADH2 and NADH. That is true. Fatty acid oxidation directly produces many ADP molecules. So the keyword here is directly. No, it does not directly make many ATP molecules here. Right. So we never cited that as a feature when it comes to fatty acid oxidation. So this statement here would be incorrect. Later on, we'll see how exactly this works, but for now, we know that directly, it doesn't produce many ATP molecules.

Intro to Fatty Acid Oxidation Concept 2

Now in this video, we'll talk about the phases of fatty acid oxidation. Fatty acid oxidation takes place in three successive phases. In phase A, we have what's called activation. Here, it prepares the fatty acid for oxidation by converting it into a fatty acyl CoA. To do this, we have to consume ATP. In phase B, we have what's called transport. Here, the fatty acyl CoA moves from the cytosol to the mitochondrial matrix via the carnitine shuttle. And in phase C, we have oxidation. Here the beta oxidation pathway breaks the fatty acid chain into multiple Acetyl CoA. In addition to this, it's going to produce our high energy molecules in the form of FADH₂ as well as NADH.

If we take a look at this overview, we start out with our fatty acid. By consuming ATP, we're able to convert it into our fatty acyl CoA. It then goes into our transport phase where it's transformed into our fatty acyl carnitine, so CAR here. And then finally, we have oxidation, where it's going to be oxidized into multiple Acetyl CoA molecules and in addition, our high energy molecules of FADH₂ and NADH. So, this image gives us a good overview of what fatty acid oxidation entails.

Intro to Fatty Acid Oxidation Example 2

In this example, it asks which of the following is an incorrect description of a phase in fatty acid oxidation. Remember, there are three phases: A, B, and C. We have activation, transport, and oxidation.

A. In the cytosol, fatty acids are activated by conversion into fatty acyl CoA. Yes, this is true. It does so by consuming an ATP. Fatty acids activated by the Carnitine are transported into the mitochondrial matrix. Okay. By the malate-aspartate shuttle. No. It is done by the carnitine shuttle. This is false. And so far, this looks like our incorrect description.

B. Fatty acids undergo beta oxidation in the mitochondrial matrix to produce Acetyl CoA. They produce multiple Acetyl CoA molecules depending on the length of the fatty acid chain, FADH₂, and NADH. This is true.

C. The carnitine shuttle transports activated fatty acids from the cytosol to the mitochondrial matrix. This is true.

So, out of all our statements, only option B is an incorrect one.

Red blood cells do not have mitochondria. Can red blood cells use fatty acid oxidation to produce energy?

• A. Yes
• B. No

For the biochemical pathways listed below, indicate which of the following energy carriers are produced in each: ATP (A), FADH₂ (F), NADH (N), or none (X).

a) Glycolysis (_______)

b) β-Oxidation (_______)

c) Kreb’s cycle (_______)

d) Fatty acid activation (_______)

In this practice question, it says, for the biochemical pathways listed below, indicate which of the following energy carriers are produced in each. So we have ATP which represents a, FADH2 which is f, NADH which is n, and then none which is x. Here we have glycolysis. So remember, glycolysis, the high energy molecule that we will produce would be NADH. So here we'd say n is involved. But besides n, what else could we make from glycolysis? We could also have the creation of ATP. So here we'd say both a and n. Next, we have beta oxidation which is the third phase when it comes to fatty acid oxidation. We're going to say here it's in this step that we make our high energy molecules of FADH2 and NADH. We'd also create some Acetyl CoA, but Acetyl CoA is not an option here. So this would just be f+n. Krebs cycle or the citric acid cycle, we know that that's leading us into stage 3 when it comes to food catabolism. We know that it makes different things. It definitely makes ATP. It makes FADH2, and it also makes NADH. Finally, we have fatty acid activation. In order to activate this, we're not producing ATP, we're consuming ATP, so ATP can't be an answer. We're not going to be creating high energy molecules in the form of FADH2 or NADH. So here, it would just be none. So x would be the letter that we place for the final option. Alright. So this is how we could talk about the high energy molecules produced in each of these processes or not produced when it comes to fatty acid oxidation or fatty acid activation.

Here’s what students ask on this topic:

What is fatty acid oxidation and why is it important?

Fatty acid oxidation is a metabolic process where fatty acids are broken down to produce energy. It occurs in three phases: activation, transport, and oxidation. Initially, fatty acids are converted to fatty acyl CoA using ATP. These molecules are then transported to the mitochondrial matrix via the carnitine shuttle. In the final phase, beta oxidation breaks down fatty acyl CoA into multiple Acetyl CoA molecules, generating high-energy molecules NADH and FADH₂. This process is crucial for ATP production, providing energy for various cellular functions, and can also lead to the formation of ketone bodies, which are important during periods of low carbohydrate intake.

What are the three phases of fatty acid oxidation?

The three phases of fatty acid oxidation are activation, transport, and oxidation. In the activation phase, fatty acids are converted into fatty acyl CoA using ATP. During the transport phase, fatty acyl CoA is moved from the cytosol to the mitochondrial matrix via the carnitine shuttle. In the oxidation phase, beta oxidation breaks down fatty acyl CoA into multiple Acetyl CoA molecules, producing high-energy molecules NADH and FADH₂. These phases ensure the efficient breakdown of fatty acids to generate energy.

How does the carnitine shuttle function in fatty acid oxidation?

The carnitine shuttle is essential for transporting fatty acyl CoA from the cytosol to the mitochondrial matrix, where beta oxidation occurs. Initially, fatty acyl CoA is converted to fatty acyl carnitine by the enzyme carnitine acyltransferase I. This fatty acyl carnitine is then transported across the mitochondrial membrane by a translocase enzyme. Once inside the mitochondrial matrix, carnitine acyltransferase II converts fatty acyl carnitine back to fatty acyl CoA, allowing it to undergo beta oxidation. This shuttle system is crucial for the proper localization and subsequent oxidation of fatty acids.

What are the end products of beta oxidation?

The end products of beta oxidation are Acetyl CoA, NADH, and FADH₂. During beta oxidation, fatty acyl CoA is broken down into multiple Acetyl CoA molecules. Each cycle of beta oxidation also produces one molecule of NADH and one molecule of FADH₂. These high-energy molecules are then used in the electron transport chain to generate ATP, providing energy for the cell. Additionally, Acetyl CoA can enter the citric acid cycle or be used for the synthesis of ketone bodies.

What role does ATP play in fatty acid oxidation?

ATP plays a crucial role in the activation phase of fatty acid oxidation. During this phase, ATP is used to convert fatty acids into fatty acyl CoA. This activation step is necessary for the fatty acids to be transported into the mitochondrial matrix and subsequently undergo beta oxidation. The energy from ATP is required to form the high-energy thioester bond in fatty acyl CoA, making it a key step in the overall process of fatty acid oxidation and energy production.