Photosynthesis is a process utilized by plant organisms to produce carbohydrates, in the form of sugars and starches, by harnessing energy from the sun and combining this with CO2 molecules. Photosynthesis takes place in chloroplast organelles which are present in the mesophyll tissue of plant leaves. Furthermore, photosynthesis depends on the presence of chlorophyll, a green pigment, which is found in the thylakoid cells of the chloroplast.
Figure 1. This figure is a cross-section of a leaf and shows the main components of the leaf structure. The palisade layer is composed of palisade cells which are part of the mesophyll tissue found in leaves. The mesophyll of leaves is comprised of the palisade and spongy cell layers. This image has been taken from:http://en.wikipedia.org/wiki/File:Leaf_Tissue_Structure.svg.
The equation for photosynthesis is as follows:
6CO2 + 12H2O + light energy -----> C6H12O6 + 6O2
CO2 = carbon dioxide
H20 = water
C6H12O6 = glucose
O2 = oxygen
Photosynthesis requires a few major photosynthetic compounds in order to produce glucose. As already mentioned, chlorophyll, a green pigment, is required to absorb energy from the sun. Chlorophyll contains a porphyrin ring structure with a magnesium ion at its center. Furthermore, an enzyme called Rubisco is essential to this process. Rubisco is required for carbon fixation during the Calvin cycle, creating a 6-carbon compound which gets broken down into two smaller three carbon compounds.
Overall, photosynthesis involves two components: the light cycle and the dark cycle. CO2 is needed for the dark cycle and is acquired through a plant's stomata, which is a pore on the epidermis of leaves regulating gas exchange. However, the intake of CO2 through the stomata represents a trade-off with the loss of water.
The end objective of photosynthesis is to produce sugars for plants to use as a food source. Photosynthesis is a rather complex process and also varies between different types of plants, such as between C3, C4 and CAM plants.