PHOTORESPIRATION
Introduction to Photorespiration Earlier it was supposed that the rate of respiration in light was almost equal to the respiration in darkness. Recently it has been observed that light affects respiration and the rate of respiration in light about 3 to 5 times more than the respiration in darkness. This led to the discovery of photorespiration. It is also known as C2 cycle. The existence of photorespiration was first demonstrated by Decker in the year 1955 and 1959. He and his associates were the first to use the term photorespiration. Photorespiration is a process which involves loss of fixed carbon as CO2 in plants in the presence of light. It is initiated in chloroplasts. This process does not produce ATP or NADPH and is a wasteful process. Photorespiration occurs usually when there is the high concentration of oxygen. Under such circumstances, RuBisCO, the enzyme that catalyses the carboxylation of RuBP during the first step of Calvin cycle, functions as an oxygenase. Some O2 does ...