10 Points on Photosynthesis

• Photosynthesis converts light energy (carried by photons) into ATP, which is a molecule which can store energy in a form that is usable by the plant.
• Chloroplasts are transparent organelles which contain grana, which are stacks of thylakoids which in turn contain a green pigment called chlorophyll. This is where photosynthesis takes place.
• Chlorophyll absorbs all wavelengths of light except for green (and yellow), which they reflect to our eyes.
• An electron transfer chain is used to synthesize ATP
• Oxidation occurs when electrons are lost. Reduction occurs when electrons are gained.
• PS2 (Photosystem 2) is simulated by light of wavelength 680 nm and takes two electrons from a water molecule, breaking the covalent bond which holds it together. Oxygen and H2 are separated.
• The electrons travel through the transport chain using oxidation and reduction reactions. It goes from PS2 to PQ to B6F. B6F pumps hydrogen ions into the chloroplast when it gets the electron, and then passes it on to PC.
• The next link in the chain is PS1 (Photosystem 1). It gets simulated by light of wavelength 700 nm and is then reduced. The electron then goes to Fd (ferrodoxin) and FNR.
• NADP is the end of the chain, and a positive hydrogen ion (proton) neutralizes it.
• ATP is formed by ATP synthase. It spins ADP around. (when this combines to one phosphate it becomes ATP). The hydrogen ions 'slow' the spinning down and the last phosphate attaches to the combination and becomes ATP.