Q. 18.54 - An Introduction to General, Organic, and Biological Chemistry

Question

Why does ${\mathrm{FADH}}_2$ yield data-custom-editor="chemistry" $1.5 \mathrm{ATP}$, using the electron transport system, but data-custom-editor="chemistry" $\mathrm{NADH}$ yields data-custom-editor="chemistry" $2.5 \mathrm{ATP}$?

Step-by-Step Solution

Answer

The reason behind the different yield of ATP is the reaction of $\mathrm{NADH}, {\mathrm{FADH}}_2$ with different complexes.

Step 1: Given information

We need to find the reason for the different yields of ATP. 

Step 2: Explanation

We know that,

The energy released when $\mathrm{NADH}$ enters the electron transport complex I is used to make $3 \mathrm{ATP}$. When compared to complex I, electron transport in complex II has a lower energy level. As a result, only $2 \mathrm{ATP}$ is generated from the energy released after ${\mathrm{FADH}}_2$ oxidation when it enters electron transport at complex II.