PGA as the firstCO2fixation product was discovered in photosynthesis o...
Photosynthesis and CO2 fixation
Photosynthesis is a process by which plants, algae, and some bacteria convert sunlight, carbon dioxide, and water into organic compounds and oxygen. This process is essential for life on earth as it produces the oxygen that we breathe and provides food for organisms that cannot produce their own.
CO2 fixation is the process by which carbon dioxide is transformed into an organic molecule that can be used by living organisms. This process is important because carbon dioxide is an essential component of the atmosphere, but it is not readily available to most organisms in its gaseous form.
PGA as the first CO2 fixation product
PGA (phosphoglyceric acid) is the first stable product of CO2 fixation in photosynthesis. It is formed when carbon dioxide combines with a five-carbon sugar called ribulose bisphosphate (RuBP) in a reaction catalyzed by the enzyme Rubisco (ribulose bisphosphate carboxylase/oxygenase).
Discovery of PGA
The discovery of PGA as the first CO2 fixation product was made by Melvin Calvin and his colleagues in the 1940s. They used radioactive carbon-14 to trace the movement of carbon through the photosynthetic process and discovered that PGA was the first stable product of CO2 fixation.
Source of PGA
PGA is produced in the stroma of the chloroplasts in plant cells. It is then used to make glucose and other organic compounds through a series of enzyme-catalyzed reactions known as the Calvin cycle.
Role of algae in PGA discovery
Algae played a crucial role in the discovery of PGA as the first CO2 fixation product. Algae are photosynthetic organisms that are capable of fixing carbon dioxide in a similar way to plants. They were used by Calvin and his colleagues as a model system to study photosynthesis and CO2 fixation.
Conclusion
In conclusion, PGA was discovered as the first CO2 fixation product in photosynthesis by Melvin Calvin and his colleagues in the 1940s. This discovery was made using algae as a model system and has since been confirmed in plants and other photosynthetic organisms.
PGA as the firstCO2fixation product was discovered in photosynthesis o...
Calvin, Benson and their colleagues in California, U.S.A. fed Chlorella and Scenedesmus with radioactive ,4C in carbon dioxide. Radioactive carbon, l4C has a half life of 5568 years. Therefore, the path of CO2 fixation can be easily traced with its help. Algal suspension illuminated and carrying out photo- synthesis with normal carbon dioxide was supplied l4CO2. The algae was killed at intervals in near boiling methanol. It immediately stopped photosynthesis activity due to denaturation of enzymes. Alcohol was evaporated and after crushing the alga, the product was made into paste. The paste was placed on paper chromatogram and the different compounds were separated by two dimensional chromatography. The radioactive compounds were identified by comparing their position on the chromatogram with standard chemicals. Calvin and co-workers found that after three seconds, radioactivity appeared in phosphoglyceric acid or PGA. Phosphoglyceric acid is, therefore, the first stable product of photosynthesis.