Photosystem II is the photosynthetic complex responsible for producing the oxygen we breathe. It does this by splitting two water molecules into four protons and one molecule of O2. Clicking on each of the thumbnail images will bring up a larger, labeled version of the described scene.

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	The splitting of water molecules occurs at the oxygen-evolving complex. Here we see the second of two water molecules being split.
	Once two molecules of water have been split, one molecule of molecular oxygen (O2) is produced. This final product of the Photosystem II reaction is the oxygen we breathe.