I had science today, and I learned about photosynthesis!
Photosynthesis! Its how plants make energy!
COOL! How does it work?
There are four steps, Photosystem II, which happens first, its wierd, photosystem I, the electron transport chain, and the Calvin Cycle. In Photosystem II, Water is taken in, and separated into Oxygen, H+(protons) and electrons (e-). Photons from light are absorbed by the pigments in thylakoid in the chloroplasts in leaves. The photons excite the electrons, which have two fates: move to another atom w/ energy, or pass energy to another electron, which has the same choices. When the energy reaches Chlorophyll A, an e- goes into the electron transport chain with its energy.
What about the others?
The energy from the electrons powers the pumps that move protons from the stroma into the thylakoid via active transport (against the concentration gradient). ATP is created as H+ ions flow out of the thylakoid. It is like a spinning door and energy is harnessed to create the ATP (called ATP synthase). The remaining e- electrons are passed to photosystem I where the same light absorption steps take place as in Photosystem II. Water is not inputted here, but the energy transferal still takes place, which chlorophyll A passing an electron to another electron chain which adds the e- to NADPH to make a high energy electron carrier.
And what about the Calvin thing?
In the Calvin cycle, CO2 bonds with Rubisco to make an organic molecule. ATP and NADPH are used to make G3Ps from that molecule (small sugar). Some G3Ps are released, while others are recycled. To recycle the molecules, another ATP is used to regenerate the organic molecule.