Photosynthesis Essay, Research Paper

Photosynthesis occurs in 3 main stages: energy is captured from sunlight, then

it?s converted into chemical energy and stored in organic molecules.

Photosystems are light harvesting units of the thylakoid membrane. Each

photosystem has four hundred pigment molecules. A photon hits the pigment

molecules and travels through each molecule and then reaches the reaction center

as shown in figure 1-1. The thylakoid membrane has two photosystems, photosystem

1 & 2. The reaction center in photosystem 1 is called P700 because this

pigment is best at absorbing 700 mm light. Photosystem 2?s reaction center is

called P680 because it is best at absorbing 680 mm light. Calvin Cycle The

Calvin cycle begins by incorporating Co2 from the air into molecules in the

chloroplast. This action is called carbon fixation. The next thing it does is

add electrons to the fixed carbon to make it carbohydrate. The power of the

Calvin cycle comes from NADPH. The Calvin cycle also needs energy from ATP,

which is generated by light reactions. This is reaction is called ?dark

reactions? because it does not directly need light to work. So basically all

the Calvin cycle does is make sugar with out light but with help from ATP &

NADPH.