Paper number two is ATP Formation Caused by Acid-Base Transition
of Spinach Chloroplasts by Andre Jagendorf and Ernest Uribe, published in the Proceedings of the National
Academy of Sciences in 1966. This paper answers Peter Mitchell’s
second question: What do electron transport chains do? Jagendorf and Uribe
isolated chloroplasts from spinach. Then, they added acid to the chloroplasts. They kept them in the dark so that no photosynthesis could occur. Jagendorf and Uribe then rapidly raised the pH of their experimental system. They used different starting
and ending pH values. The details of their start and
endpoints are in the case study. Changing the pH created a proton gradient across the chloroplast membrane. Just by changing the pH the chloroplasts generated ATP.