Photosynthesis

Photosynthesis is a process of producing glucose by plant using the energy from sunlight, carbon dioxide and water. Here, light energy is converted into chemical energy. During photosynthesis process oxygen is released which absolutely need to breathe and stay alive. Typically, using chlorophyll, photosynthesis process is happened in the chloroplasts. Chlorophyll is the green pigment of photosynthesis. In the early evolutionary history of life, first photosynthetic organisms were developed wherein hydrogen or hydrogen sulfide was the source of electrons instead of water. Globally, photosynthesis can capture huge amount of energy. It is approximately six times higher than our existing power consumption. Photosynthetic organisms can also convert huge amount of carbon into biomass per year. 

Basically, photosynthesis happens in plant leaves. The upper and lower epidermis, the mesophyll, the vascular bundles and the stomates are parts of a typical leaf. Epidermis are the outer layer of cells surrounding the body of an organism like a plant leaf or our skin. No chloroplasts exists in the upper and lower epidermal cells, thus no photosynthesis create there. Primarily, they provide protection for the rest of the leaf. In the lower epidermis, stomates holes are created in order to exchange air. Here, carbon dioxide enters and oxygen exits. Vascular bundles of leaf transport required water and nutrients around the plant. The mesophyll cells contain chloroplasts wherein photosynthesis creates.Chloroplasts are photosynthetic organelle in plant. 

Parts of a chloroplast includes outer and inner membranes, inter membrane space, stroma and thylakoids stacked in grain. Stroma is the the fluid within chloroplasts. Thylakoid is one of the sacs within a chloroplast. Membranes of the thylakoid contains chlorophyll. Absorbing red and blue light, it appears to us as green color. It makes red and blue colors visually unavailable to our eyes. Because, green light is not absorbed in chlorophyll. So, finally it appears as green color to our eyes. However, it is the energy from the absorbed red and blue light. It is used to do photosynthesis. As plants cannot absorb green light, it cannot be used to do photosynthesis. 

In the thylakoid membrane, light reaction occurs and converts light energy into chemical energy. In the light reaction, chlorophyll and few other pigments like beta-carotene are associated. Each of these distinguished color pigments can absorb quite distinguished color of light and transfers its energy into the central chlorophyll molecule in order to do photosynthesis. 

Energy collected through the light reaction is stored by forming a chemical called ATP (adenosine triphosphate). ATP is a compound wherein cells store energy. It contains nucleotide adenine bonded to ribosomes and three phosphate groups. Dark reaction happens in the stroma within the chloroplast and converts carbon dioxide into glucose.