This process begins when light energy from the sun excites electrons in what is called "photosystem II." A water molecule is also split, which causes an electron to release into the electron transport system and a hydrogen ion to release into the thylakoid space. This also creates oxygen as a waste product.
The electrons are then moved from photosystem II to the electron-acceptor molecule, which is located in the thylakoid membrane.
Two of the G3P molecules exit the cycle so they can be used to help produce glucose and other compounds.
In the final step, rubisco, an enzyme, converts the ten G3P that are left into RuBP (ribulose 1, 5-bisphosphates.) These are 5-carbon molecules. When these molecules combine with new carbon dioxide, the cycle continues.