Question

Compare and Contrast how electron transport is used to generate proton gradients in chloroplasts and mitochondria. Include more specific details for more points.

Answer 1

Electron transport chain (ETC) refers to a series of complexes involved in the transfer of electrons from electron donors to electron acceptors through the reduction and oxidation reactions.

The similarities between the ETC in mitochondria and chloroplasts are as follows-

1. Both involve the electron transport chains on their inner membranes.

2. The energy produced pumps the protons against their concentration gradient across a membrane.

3. ATP synthase is used.

4. Two protons provide energy for the production of three molecules of ATP.

The differences between the ETC in mitochondria and chloroplasts are as follows-

Mitochondria- It uses the process of oxidative phosphorylation and chemical energy from the reduction-oxidation reactions. The electron transport chain occurs in the cristae. The coenzymes involved include the NAD and FAD. ATP synthase is located in the cristae. The protons are pumped out of the matrix. The final electron acceptor is the oxygen.

Chloroplast- It uses the process of photophosphorylation and the light energy. The electron transport chain occurs in the thylakoid membrane. The coenzyme involved is the NADP. ATP synthase is located in the thylakoid membrane. The protons are pumped into the thylakoids. The final electron acceptor is the chlorophyll in cyclic photophosphorylation and NADPH+ in the non-cyclic photophosphorylation.