Photosynthesis: Chemical energy from light
Life on earth is dependent on
photosynthesis, the process in which solar
light is converted into chemical energy and stored as
carbohydrates. The carbohydrates are, finally,
degraded to carbon dioxide and water in the cell
respiration in a reaction requiring molecular oxygen.
The liberated energy is utilized to power the life
processes. In photosynthesis, the carbon dioxide and
water are used to resynthesize carbohydrate, while
molecular oxygen is released into the atmosphere as a
waste product. Thus, not only is present life on
earth largely a result of photosynthesis but so is
the air we all breathe.
Our knowledge about photosynthesis, respiration and other membrane-associated processes is limited due to the lack of information about the molecular organization of the membrane proteins involved, a problem which derives from difficulties in crystallizing these proteins. The crystals are used for the determination of the 3-dimensional structure of the proteins by X-ray diffraction, a technique in which X-rays are analyzed after being scattered by the molecules in a crystal.