The two carbons that remain after the addition of malonyl-CoA are added as an acetyl group with the carbonyl carbon on the interior of the chain, which is to say a ketone. Then, the carbonyl is reduced to form an alcohol. Next, the alcohol is dehydrated to form an alkene. Finally, the alkene is reduced to saturate the chain, forming an alkyl group.

Carnitine transports fatty acids from the cytosol to the mitochondria. Acetyl-CoA is converted to citrate as it exits the mitochondria and enters the cytosol.

In fatty acid synthesis, all of the enzymes listed are are regulated by insulin. Pyruvate dehydrogenase transforms pyruvate into acetyl-CoA. Glucokinase transforms glucose in glucose 6-phosphate. Acetyl-CoA carboxylase converts acetyl-CoA to malonyl-CoA. Fatty acid synthase converts malonyl-CoA to fatty acid palmitate. Insulin regulation is essential for proper utilization of dietary carbohydrates and lipids after meals. 

The citrate shuttle moves acetyl-coenzyme A (CoA) from the mitochondria to the cytosol to make it available for fatty acid synthesis. The process involves multiple reactions and enzymes such as citrate lyase. Citrate acts as as a carrier agent for acetyl-CoA molecules from the mitochondria to the cytoplasm and in reverse. Oxaloacetate, a product of citrate lysis in the cytoplasm is not moved directly back in the mitochondria, but rather is converted back to malate and pyruvate.

Acetyl-CoA carboxylase is essential for fatty acid synthesis, it provides malonyl-CoA, necessary for production of palmitate, a fatty acid. The enzyme is regulated via phosphorylation and dephosphorylation. Insulin activates the enzyme by dephosphorylation. Glucagon and epinephrine deactivate on the other hand the enzyme by phosphorylation (adding a phosphate group to the molecule). Citrate activates the enzyme while palmitoyl-CoA, the end product of fatty acid synthesis, inhibits it.

Glycogen synthase is turned on when unphosphorylated. The enzyme responsible for this is protein phosphatase I. Protein kinase A inactivates glycogen synthase. Low glucose concentration causes a release in glucagon, which activates glycogen phosphorylase and deactivates glycogen synthase. 

An oxidoreductase catalyzes the transfer of electrons from one molecule to the other, usually using ; i.e., it is an enzyme that catalyzes a redox reaction. Trypsin cleaves peptide bonds. Hexokinase phosphorylates hexose sugars. Glucose 6-phosphatase hydrolyzes glucose 6-phosphate into a phosphate group and glucose. Aspartate amino-transferase catalyzes the transfer of an amino group between aspartate and glutamate. Lactate dehydrogenase interconverts pyruvate to lactate, and at the same time  and .

The pyruvate dehydrogenase complex catalyzes the following reaction:

Since it is product inhibited, acetyl-CoA will inhibit the complex. 

There are 3 enzymes in glycolysis that carry out irreversible reactions: phosphofructokinase-1 (PFK-1), hexokinase and pyruvate kinase. While phosphatases are used to reverse the reactions for PFK-1 and hexokinase, they are not used in reversing the pyruvate kinase reaction. 2 enzymes are needed to convert pyruvate back into phosphoenolpyruvate (PEP). First, pyruvate carboxylase converts pyruvate into oxaloacetate, and then PEP carboxykinase converts this into PEP.

Fructokinase catalyzes the reaction of fructose converting into fructose-1-phosphate. Glycogenin acts as a primer for glycogen synthesis, by polymerizing the first few molecules of glucose. Glycogen synthase converts glucose to glycogen. Phospholipase hydrolyzes phospholipids.