What is the Difference Between Electron Transport Chain in Mitochondria and Chloroplasts?

The electron transport chain (ETC) is a series of protein complexes and molecules that facilitate the transfer of electrons and the synthesis of ATP in both mitochondria and chloroplasts. However, there are differences between the ETCs of mitochondria and chloroplasts:

1. Location: In chloroplasts, the ETC is embedded in the thylakoid membrane, while in mitochondria, the ETC is embedded in the inner mitochondrial membrane.
2. Process Name: The ETC in mitochondria is called 'oxidative phosphorylation,' as it utilizes chemical energy from NADH and FADH2. In contrast, the ETC in chloroplasts is called 'photo-phosphorylation,' as it uses light energy.
3. Ultimate Source of Energy: In mitochondria, the ultimate source of energy is glucose (or another food molecule), while in chloroplasts, it is sunlight.
4. Electron Donor and Acceptor: In mitochondria, the electron donor is NADH and FADH2, and the final electron acceptor is oxygen. In chloroplasts, water is the electron donor, and oxygen is also the final electron acceptor.
5. Region of High and Low H+: In mitochondria, the region of high [H+] is the intermembrane space, and the region of low [H+] is the matrix. In chloroplasts, the region of high [H+] is the thylakoid lumen, and the region of low [H+] is the stroma.

Despite these differences, both mitochondria and chloroplasts have the same function: to maintain a gradient of hydrogen ions that can be used to power chemiosmosis and produce ATP.

Comparative Table: Electron Transport Chain in Mitochondria vs Chloroplasts

Here is a table comparing the differences between the electron transport chain (ETC) in mitochondria and chloroplasts:

This table highlights the key differences and similarities between the electron transport chains in mitochondria and chloroplasts. Both processes utilize ATP synthase to synthesize ATP, but they occur in different organelles and use different sources of energy.