Importance of Photosynthesis
Photosynthesis is a process during which energy from light is harvested and used to drive synthesis of organic carbohydrates from carbon dioxide and water, generating oxygen. Photosynthesis is the only way that radiant energy from the sun can be converted into organic molecules for plants and animals to consume.
Participants in Photosynthesis
Chloroplasts are organelles specialized for photosynthesis. Inside chloroplasts are chlorophyll, proteins which can absorb light. Photosystems are many proteins together which can gather and amplify light energy. NADPH is an energy carrier in plants and ATP synthase produces the ATP.
The Light Reaction
Pigments in photosystem II absorb light. The light excites electrons, energizing
them. The high-energy electrons move to photosystem I and get re-energized. The electrons’ energy is harvested to pump H+ ions from the stroma into the thylakoids. NADP+ picks up some of the H+ and electrons to become NADPH. The leftover H+ diffuse back out to the stroma, passing through ATP synthase. ATP synthase produces ATP.
The Dark reaction – Calvin Cycle
The dark reaction is also called the light-independent reaction or the Calvin Cycle. It occurs in the stroma of chloroplasts of plant cells. These processes do not use light (hence dark reaction). Carbon dioxide is combined with the energy produced in the light reaction t make sugars for plant growth and energy.