Question

Question: Describe the types of reactions required to produce a molecule of cholesterol.

Short answer

The types of reactions involved in the production of cholesterol are decrboxylation, condensation, reduction, oxidation, isomerization, and cyclization.

Step-by-step solution

Biosynthesis of cholesterol

The biosynthesis of cholesterol occurs from Acetyl-CoA. The acetyl-CoA converts toHMG-CoA (hydroxymethylglutaryl-CoA), a cholesterol precursor by the help of thiolase and HMG-CoA synthase. The HMG-CoA is converted to isopentenyl pyrophosphate through four reactions which are:

$$\begin{gathered} HMG-CoA+2NADPH\underset{HMG-CoAreductase}{\to }Mevalonate+2NAD{P}^{+}+CoA \\ Mevalonate+ATP\underset{}{\to }Phosphomevalonate+ADP \\ Phosphomevalonate+ATP\underset{}{\to }5-Pyrophosphomevalonate+ADP \\ 5-Pyrophosphomevalonate\underset{}{\to }isopentylpyrophosphate+P_i+ADP+C{O}_2 \end{gathered}$$

Ispentenyl pyrophosphate isomerase converts isopentenyl pyrophosphate to dimethylallyl pyrophosphate. These molecules condense to formsqualene in three reactions:

$$\begin{gathered} Dimethylallylpyrophosphate+Isopentylpyrophosphate\underset{pentyltransferase}{\to }Gernaylpyrophosphate+P_i \\ Geranylpyrophosphate+Isopentylpyrophosphate\underset{pentyltransferase}{\to }Farnylpyrophosphate+P{P}_i \\ Farnylpyrophosphate+Famylpyrophosphate+NADPH\underset{Squalenesynthetase}{\to }Farnylpyrophosphate+P{P}_i \end{gathered}$$

The cyclization of squalene results in the formation of cholesterol.

Types of reaction in cholesterol biosynthesis

Cholesterol biosynthesis involves several types of reactions, including:

• Reduction
• Phosphorylation
• Decarboxylation
• Isomerization
• Condensation
• Cyclization
• Oxidation