Calvin cycle is discovered by Melvin Calvin

The Calvin cycle, also known as the Calvin-Benson cycle or the C3 cycle, is a series of biochemical reactions that take place in the stroma of chloroplasts during photosynthesis. It was discovered by Melvin Calvin, an American biochemist, in the 1950s.

Background Information
Prior to the discovery of the Calvin cycle, scientists knew that during photosynthesis, plants convert carbon dioxide and water into glucose and oxygen. However, the specific steps and enzymes involved in this process were not well understood.

Experimental Setup
Melvin Calvin and his colleagues conducted experiments using radioactive isotopes of carbon to trace the path of carbon atoms during photosynthesis. They used a type of algae, called Chlorella, which could be easily grown in the lab. The algae were exposed to carbon dioxide containing a radioactive isotope, carbon-14.

Discovery of the Calvin Cycle
Through their experiments, Calvin and his team were able to trace the movement of carbon atoms in the Chlorella cells. They discovered that carbon dioxide is first incorporated into a 3-carbon compound called phosphoglyceric acid (PGA) through a series of reactions. This process is known as carbon fixation.

The PGA is then converted into a 3-carbon sugar called glyceraldehyde-3-phosphate (G3P) through a series of reduction reactions. Some of the G3P molecules are used to regenerate the starting molecule of the cycle, while others are used to produce glucose and other organic compounds.

Calvin and his colleagues were able to identify the enzymes involved in each step of the Calvin cycle, including ribulose bisphosphate carboxylase (also known as Rubisco), which catalyzes the carbon fixation reaction.

Significance of the Discovery
The discovery of the Calvin cycle by Melvin Calvin and his team was a significant milestone in understanding the process of photosynthesis. It provided a detailed understanding of how plants convert carbon dioxide into glucose, which is essential for their growth and survival.

The knowledge gained from Calvin's research has had numerous applications in the fields of agriculture, biofuels, and climate change. It has allowed scientists to develop more efficient crop plants, improve photosynthetic efficiency, and better understand the global carbon cycle.

In recognition of his groundbreaking work, Melvin Calvin was awarded the Nobel Prize in Chemistry in 1961. His discovery of the Calvin cycle has had a lasting impact on our understanding of photosynthesis and its importance in the world around us.