Light Reactions

In light reactions, the goal is to transfer solar kinetic energy to chemical potential energy. This is first done by the absorption of a photon of light. Plant pigments are molecules that selectively absorb light energy at wavelengths. A pigment molecule absorbs a photon of light one of pigments electrons jumps to an energy level further than the nucleus. The electron has more potential energy here. The electron now has raised from the ground state to an excited state. Pigments of photosynthesis 1 & 2 have to catch them and use their energy. The sunlight becomes energy ADP becomes ATP, NADP+ becomes NADPH, and water becomes oxygen. The Calvin cycle constructs G3P a3 sugar carbon very rich in energy. It’s starting energy is regenerated. It starts with a 5-carbon molecule of RuBP then it adds one CO2 to make it into a 6-carbon molecule. This forms an unstable product so it breakes in half into two 3- carbon molecules. Now G3P is formed using energy from ATP and electrons from NADPH. Some G3P recycles so cycle continues 2 G3P can make Glucose. In the cycle ATP makes ADP NADPH makes NADP and CO2 makes G3P. The energy in photosyntsis is located as solar energy in the beginning and winds up kinetic at the end from going from sunlight to electron carriers. At the end of the Calvin cycle energy becomes G3P to power the plant. Sunlight is electromagnetic energy At the end of light reactions the energy is in form of glucose while in the calvin cycle into G3P another form of