The electron transport chain is a way building energy for plants and producing energy for animals. It involves similar processes in both plant and animal cells, each using the other's waste products that are produced as a result of photosynthesis and cellular respiration.
In plants, the chloroplast is the site of energy production. Chloroplasts take carbon dioxid, water, and use light energy from the sun to produce glucose (simple sugar) and give off oxygen as a waste product. The reactions of the electron transport chain may be seen below:
CO2 + H2O + light ---> NADP+ ---> NADPH+ + (H+) + O-2 ---> C6H12O6 + O2
In the mitochondrion, the reverse process occurs for the animal cell. Mitochondrion take the glucose out of food, and breathe in oxygen from the air. The oxygen is converted over to water, the NADH+ is converted to NAD+, and succinate to fumarate, as shown below:
C6H12O6 + O2 ---> H+ + O2-2 + NADH+ ---> NAD+ + H2+2 + O2-2 ---> CO2 + H2O + energy (ATP)