Oct 10, 2009


Photosynthesis takes place in the chloroplast. Photosynthesis occurs in 2 stages. The light reaction and the dark reaction. Light reaction occurs in the grana of the chloroplast. Light is absorbed by chlorophyll. Then it excites the electron in the chlorophyll. Electrons go through a transfer system and produce ATP. Light energy also split water molecules into hydrogen ions and hydroxyl ions (photolysis of water). Oxygen is released as by product.

Dark reaction occurs in the stroma of the chloroplast without the presence of sunlight. ATP and hydrogen (from photolysis of water) are used to reduce carbon dioxide into glucose. Glucose produced will be converted to starch and stored or transformed into sucrose and transported or used for synthesis of cellulose or converted to amino acids and fatty acids.