Final answer:
Lauric acid production requires five cycles of the fatty acid synthesis pathway, beginning with an acetyl-CoA and adding two carbons each cycle via malonyl-CoA utilizing NADPH
Step-by-step explanation:
The production of lauric acid, which is a fatty acid with a 12-carbon chain, requires a series of enzymatic cycles to attach carbon atoms two at a time to a growing acyl chain connected to the acyl carrier protein (ACP). Since the synthesis pathway starts with a 2-carbon molecule (acetyl-CoA) and each cycle adds 2 carbons, 5 total cycles are needed to produce a 12-carbon fatty acid like lauric acid. The initial acetyl-CoA contributes 2 carbons, and each subsequent cycle contributes an additional 2 carbons through the use of malonyl-CoA. Thus, with 1 initial cycle and 4 additional cycles (2 + (2 x 4)), we reach the 12 carbons necessary for lauric acid.
The cycle of fatty acid synthesis consists of four key reactions, each catalyzed by a specific enzyme, utilizing NADPH as a reducing agent. The reactions include the reduction of acetoaceyl-S-ACP, dehydration to trans-A2-enoyl-S-ACP, and further conversion to saturated acyl-S-ACP. After reaching palmitoyl-ACP, synthesis ceases and further modifications occur outside of the FAS complex. Throughout these reactions, ACP serves as a carrier, while coenzyme-A forms an acyl-CoA in the cell. The pathway is repeated until the desired chain length is reached, showing a similarity to the beta oxidation process but with main reactions occurring in reverse.