3-L-hydroxyacyl-CoA dehydrogenase converts 3-L-Hydroxyacyl-CoA to beta-Ketoacyl-CoA, forming the high energy redox cofactor  from . This reaction oxidizes the hydroxyl group on the beta carbon of 3-L-hydroxyacyl-CoA to a carbonyl group, and adds a hydrogen with 2 high energy electrons to .

Beta-Ketoacyl-CoA thiolase converts beta-Ketoacyl-CoA back to acetyl-CoA and a fatty acyl-CoA two carbons shorter than the original fatty acyl-CoA. The new cofactor of acyl-CoA bonds to the beta carbon of beta-Ketoacyl-CoA, and thus the beta carbon of beta-Ketoacyl-CoA becomes the new alpha carbon of the new fatty acyl-CoA. The new fatty acyl-CoA can then re-enter into beta oxidation pathway.

Of the above terms, lipase is the term specifically given to the class of enzymes that hydrolyzes fats. A ligase joins two molecules together, so it definitely could not be involved in the hydrolysis (breakdown) of fats. Proteases on the other hand are involved in protein breakdown. Kinases and phosphatases are both involved in removing and transferring phosphate groups.

Cis-enoyl-CoA isomerase has the important role of shifting a double bond in an unsaturated fatty acid to make the molecule degradable. Without this important enzyme, many unsaturated fatty acids would not be able to completely go through beta-oxidation.

Fatty acids are broken down in the mitochondria to produce acetyl-CoA. The process is called beta-oxidation. Acetyl-CoA is then used to produce energy via the citric acid cycle pathway. Fatty acids cannot cross the mitochondrial membrane directly without the use of the carnitine shuttle.The process described in the question represents the carnitine shuttle pathway, which allows activated fatty acids (fatty acids with CoA attached) to cross the mitochondrial membrane so they can be broken down by beta-oxidation. Fatty acid synthetase activates the fatty acid on the outer mitochondrial membrane by attaching a CoA group. Carnitine acyltransferase 1 exchanges the CoA with carnitine forming fatty acyl carnitine. Fatty acyl carnitine is shuttled across the membrane through the carnitine transporter. On the inner side of the membrane, carnitine acyltransferase 2 removes carnitine and forms fatty acid-CoA which can then be processed by beta-oxidation.

Thiolase is an enzyme that performs a reaction forming acetoacetyl-CoA from two molecules of acetyl-CoA. This reaction is the first step in the process of converting acetyl-CoA molecules to ketone bodies.

Acetyl-CoA carboxylase catalyzes the committed step in fatty acid degradation - the step that forms malonyl-CoA. And so, in order to regulate fatty acid metabolism this is the enzyme that is most often controlled. Phosphorylating acetyl-CoA carboxylase inactivates it when it no longer needs to be functioning.

Phosphatidate is an intermediate in the synthesis of triacylglycerols and glycerophospholipids. This is simply because phosphatidate is the primary intermediate in lipid metabolism (which occurs in the synthesis of triacylglycerols and glycerophospholipids). More specifically, this intermediate is acylated to triacylglycerol through a fatty acid chain, and results in a glycerophospholipid product.

The correct answer is "Acetyl-CoA." The oxidation of fatty acids is activated by attachment to Coenzyme A to form fatty acyl-CoA, and the oxidation results in a shorter fatty acyl-CoA and acetyl-CoA. The acyl-CoA is oxidized in the citric acid cycle, where it is an important intermediate. Succinyl-CoA is also an intermediate in the citric acid cycle but is not a direct product of fatty acid oxidation. The shorter fatty acyl-CoA is oxidized further into FADH₂, but not as part of the citric acid cycle.

To answer this question, we'll need to keep in mind some of the highlights of beta oxidation. When a fatty acid is broken down by this method, the hydrocarbon chain is broken down two carbons at a time through a series of repeating reactions. These two carbons come off in the form of acetyl-CoA, with an additional generation of one molecule each of NADH and . Since we know the original chain we're starting with contains twelve carbons, we know that there will be six molecules of acetyl-CoA produced. Furthermore, in order to generate these six molecules, beta-oxidation must proceed five times. Thus, we are going to have five molecules of NADH and five molecules of . The acetyl-CoA generated from beta oxidation is able to enter the citric acid cycle. For each molecule of acetyl-CoA that goes through the cycle, 1 molecule of ATP, 1 molecule of , and 3 molecules of NADH are generated. Therefore, since six molecules will be sent into the citric acid cycle, there will be a total generation of six molecules of ATP, six molecules of , and eighteen molecules of NADH. Now, we need to add everything up. So far, we have six molecules of ATP. We also have five molecules of NADH from beta-oxidation, and eighteen from the citric acid cycle, for a total of twenty-three. We've also obtained five molecules of  from beta-oxidation, and another six from the citric acid cycle for a total of eleven. All of the NADH and  that was generated from these reactions can donate their electrons into the electron transport chain to generate ATP. The rule of thumb is that for every NADH,  molecules of ATP are produced. And for every molecules of ,  molecules of ATP is made. So, we have:

And if we add to this the six ATP that was generated directly by substrate-level phosphorylation in the citric acid cycle, that gives us a total of: