Question

To make a C20:0 fatty acid how many:

Acetyl CoA molecules are needed?

10

9

7

8

How may Acetyl CoA molecules are converted to malonyl CoA

10

9

7

8

How much NADPH is needed?

16

14

18

20

How much ATP is needed?

7

10

8

9

Answer 1

Answer-

According to the given question-

biosynthesis of fatty acid and their breakdown happened in different pathway with the help of different enzymes. three-carbon intermediate compound such as   Malonyl-CoA Is Formed by the Acetyl-CoA and Bicarbonate in an
Synthesis of long carbon chains of fatty acids are occur in 4 repeating step and in each step fatty acyl chain is added by two carbons. biosynthesis of fatty acids require acetyl-CoA , ATP which is work as group transfer, NADPH as reducing power

overall reaction can be written as for 20 carbon long fatty acid chain is-

This whole reaction is divided into two part

in First part - ,
formation of nine malonyl-CoA molecules such as -
9 Acetyl-CoA + 9 CO2 +9 ATP---------> 9 malonyl-CoA + 9ADP + 9Pi
After that nine cycles of condensation and reduction occur such as -:
Acetyl-CoA + 9 malonyl-CoA + 18 NADPH + 18 18H+ -----> C20 + 9CO2 + 10 CoA + 18 NADP + 8 H2O

Overall reaction is -

10 Acetyl-CoA + 9 ATP + 18 NADPH + 18H+ -----------> C20 + 10 CoA + 9 ADP + 9 Pi + 18 NADP + 8H2O

So

Acetyl CoA molecules are needed = 10

Acetyl CoA molecules are converted to malonyl CoA= 9

NADPH is needed = 18

ATP is needed= 9