ATP Synthase: A Molecular Motor

ATP synthase is a huge molecular complex (>500,000 daltons) embedded in the inner membrane of mitochondria. Its function is to convert the energy of protons (H+) moving down their concentration gradient into the synthesis of ATP. 3 to 4 protons moving through this machine is enough to convert a molecule of ADP and Pi (inorganic phosphate) into a molecule of ATP. One ATP synthase complex can generate >100 molecules of ATP each second.

ATP synthase can

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Photosynthesis: The Role of Light

The heart of photosynthesis as it occurs in most autotrophs consists of two key processes:

  • the removal of hydrogen (H) atoms from water molecules
  • the reduction of carbon dioxide (CO2) by these hydrogen atoms to form organic

Discovering the Secrets of Photosynthesis

van Helmont

Perhaps the first experiment designed to explore the nature of photosynthesis was that reported by the Dutch physician van Helmont in 1648. Some years earlier, van Helmont had placed in a large pot exactly 200 pounds (91 kg) of soil that had been thoroughly dried in an oven. Then he moistened the soil with rain water and planted a 5-pound (2.3 kg) willow shoot in it. He then placed the pot in the ground and covered its rim with a