How many molecules of acetyl-CoA condense to produce isopentenyl diphosphate, the precursor for the formation of terpenoids by the mevalonate pathway?

Correct option is B

In the mevalonate pathway, three molecules of acetyl-CoA are condensed to form isopentenyl diphosphate (IPP), a precursor for the biosynthesis of terpenoids. The process involves several steps, including the condensation of two acetyl-CoA molecules to form acetoacetyl-CoA, which then condenses with a third acetyl-CoA molecule to form mevalonate. Mevalonate is then converted into IPP, which serves as the building block for the synthesis of various terpenoids.

Steps of the Mevalonate Pathway:

1. Two molecules of acetyl-CoA condense to form acetoacetyl-CoA.
2. Acetoacetyl-CoA condenses with another acetyl-CoA molecule to form HMG-CoA (3-hydroxy-3-methylglutaryl-CoA).
3. HMG-CoA is then reduced to mevalonate.
4. Mevalonate is subsequently converted to isopentenyl diphosphate (IPP), the key precursor for terpenoid synthesis.

Information Booster:

1. Acetyl-CoA is derived from carbohydrates, fatty acids, and proteins and is the starting material for many biosynthetic pathways.
2. Isopentenyl diphosphate (IPP) is the basic building block for the biosynthesis of terpenoids, which are involved in various plant processes, including growth, defense, and reproduction.
3. The mevalonate pathway is one of the main terpenoid biosynthesis pathways in eukaryotes, especially in plants, fungi, and animals.
4. The formation of terpenoids involves head-to-tail polymerization of IPP molecules, eventually forming larger units such as geranyl pyrophosphate (GPP), farnesyl pyrophosphate (FPP), and geranylgeranyl pyrophosphate (GGPP).