By : Risini Udawatte, Muhyi Khan, Jaclyn Guest

•Refuted Ingenhousz's hypothesis

-Carbon dioxide was split into carbon and oxygen

-Carbon was used for the plants growth

-Oxygen was expelled as waste

Study purple and green sulfur bacteria Used Close containers Purple bacteria grew proportional to

the sulfide 2 H2A + CO2 → 2A + CH2O + H2O

• Carbon was not split to produce oxygen

• Oxygen is derived from the water in green plants

All photosynthesis require the same photochemical mechanism

He used ‘heavy water’,H2O18, to yield 18O2 gas in his experiment.

• His experiment showed that oxygen gas produced in photosynthesis comes from water

Kamen discovered all of the oxygen released in photosynthesis comes from water, not CO2.

He produced a radioactive isotope of carbon that could be used as a tracer in investigating chemical reactions in photosynthesis.

1939–1941: Ruben, Kamen and the discovery of carbon-14

• experiments on tracing the path of carbon in algae by using radioactive 11CO2 (half life, 20 min), but the results were not conclusive

• set out to discover the path of carbon in photosynthesis by incorporating the short-lived radioactive isotope Carbon – 11

• CO2 can occur in the dark and may involve processes similar to bacterial systems

• http://www.life.illinois.edu/govindjee/Part3/9_Gest_On_Ruben.pd

• Ruben, S.; Kamen, M. D. (1941), "Long-Lived Radioactive Carbon: C14", Physical Review 59 (4): 349–354Photosynthesis and phosphorylation. J. Am. Chem. Soc

.65: 279-282. 1943.

Govindjee. Bioenergetics of Photosynthesis. New York: Academic Press, 1975.

Gregory, R.P.F. Biochemistry of Photosynthesis. Belfast: Universities Press, 1971.

Rabinowitch, Eugene and Govindjee. Photosynthesis. New York: John Wiley & Sons, Inc., 1969.