Photosynthesis begins with light dependent reactions. It begins with the absorption of light. Chloroplasts in the plant absorb the light energy. After all the energy is absorbed, two molecules, ATP and NADPH are produced to be used in the Calvin Cycle. Chloroplasts are disc-like organelles that contain two main compartments essential for photosynthesis. The thylakoids and the stroma.
Electron Transport Light energy excites electrons in photosystem 2. The light energy also causes a water molecule to split, releasing an electron into the electron transport system. This breakdown of water is essential for photosynthesis to happen. The excited electrons move from photosystem 2 to a molecule in the thylakoid membrane. The molecule transfers the electrons to photosystem 1. When light appears photosystem 1 transfers the electrons to a protein called ferrodoxin. Ferrodoxin then transfers the electrons to the electron carrier NADP+, forming the molecule NADPH.
The next stage in photosynthesis is the Calvin Cycle. The Calvin Cycle has three steps. In step one the enzyme rubisco incorporates carbon dioxide into a molecule called 3-PGA. In step two the moleculeis reduced using electrons supplied from NAPDH. In step three RuBP, the molecule that starts the cycle, is regenerated so the cycle can continue.