Question

Determine how many molecules of glucose is needed for 1 molecule of palmitate (C16). Assume that all NADPH consumed in this process is also produced from glucose using the pentose phosphate pathway in which all glucose 6-phosphate entering the PPP is converted to CO2, , H2O, and NADPH (no ribose 5-phosphate is formed). Required ATP should also be synthesized from glucose.

Answer 1

we know that palmitate is a 16 carbon fatty acid. and its biosynthesis requires Acetyl CoA. glucose gave 2 molecules of Acetyl CoA during glycolysis.

so we require 8 molecules of Acetyl CoA or 4 molecules of glucose.

the reaction is as follows-

First, the formation of seven malonyl-CoA molecules

7 Acetyl-CoA + 7CO₂ + 7ATP --------------> 7 malonyl-CoA + 7ADP + 7P_i

then seven reactions cycle of condensation and reduction

Acetyl-CoA + 7 malonyl-CoA + l4NADPH + 14H⁺ ---------------> Palmitate + 7C0₂ + 8CoA + l4NADP⁺ + 6H₂O

The overall reaction process is-

8 Acetyl-CoA + 7ATP + l4NADPH + 14H⁺ ----------------> Palmitate + 8CoA + 6H₂O + 7ADP + 7P_i + l4NADP⁺