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How did Calvin discover the Calvin cycle?


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Answered 2008-01-05 19:37:06

The problem Calvin was investigating was how did the carbon in carbon dioxide get converted into the carbon in carbohydrates during phototsynthesis. This meant he had to find a way of tracing the path of the carbon as it was built up into carbohydrate: CO2 ---> substance A ---> substance B ---> etc ---> CH2O (carbohydrate) Calvin discovered the 'Calvin cycle' by choosing a suitable organism to work with, devising a clever piece of apparatus and applying two carefully-chosen techniques. The organism was a single-celled alga called Chlorella. Each cell contains a single, large chloroplast. Because it is single-celled, it can absorb carbon dioxide rapidly and can be killed rapidly, making handling easier than it would be if a larger plant had been used. The apparatus was a flat glass flask called the 'lollipop' apparatus after its shape. The flat shape meant that all of the Chlorella cells inside could receive the maximum amount of light, and so carry out the maximum amount of photosynthesis. With a spherical flask, cells in the middle would receive less light than cells at the outside, and so would photosynthesise less. The first technique he used was to track the path of carbon during photosynthesis by using a radioactive isotope, 14C. This had only recently become available in the 1940's. The advantage of using a radioactive isotope is that it was possible to detect the presence of small amounts of labelled carbon. Calvin added radioactive carbon dioxide to the culture solution containing the Chlorella cells and, after a short time, emptied the cells into a container of alcohol. The alcohol rapidly killed the cells, stopped any further reactions and started to extract the chemicals from them. By varying the time for which the cells were exposed to the radioactive carbon, CAlvin could work out the sequence of chemical reactions through which the carbon was passing. The second technique was two-dimensional paper chromatography. Chromatography is a method for separating mixtures of compounds. A mixture is added as a small spot near the base of a strip of paper. If the paper is dipped in a solvent, it will travel up the paper carrying the mixture with it. However, different substances will be carried different distances, and so the mixture will be separated. After carrying out one separation, Calvin turned the paper through 90o and carried out a second separation using a different solvent (hence the name two-dimensional). This gave a better separation of similar compounds. Having separated the substances which he had extracted from the cells, Calvin then had to find where they were on the chromatography paper! He could not see them because they were colourless. To locate the substances containing the radioactive carbon, he placed a piece of photographic film on top of the paper. The radiation given off by the 14C made the film go dark, so he could then locate where they were on the paper. This technique is called autoradiography. The final step was to identify the compounds containing the 14C. This took about 10 years! At the end, he was able to describe the sequence of compounds through which the carbon passed as it was converted from carbon dioxide to carbohydrate. He discovered that it was in fact a cycle of reactions, hence the name 'Calvin cycle'. He was awarded the 1961 Nobel Prize in Chemistry for this work. For further information see: http://en.wikipedia.org/wiki/Calvin_cycle http://en.wikipedia.org/wiki/Melvin_Calvin http://nobelprize.org/nobel_prizes/chemistry/laureates/1961/calvin-lecture.html

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Related Questions

How did melvin Calvin discover the Calvin cycle?

The Calvin cycle is the reaction that happens in plants during photosynthesis and carbon filtration without light. Melvin Calvin and two associates used the radio-active carbon 14 to trace the pattern of the carbon atoms during filtration.


Does Calvin cycle require oxygen?

No, the Calvin cycle does not require oxygen.Calvin cycle need carbon dioxide.CO2 is reduced to glucose in calvin cycle


Is the dark reaction the Calvin cycle or the citric cycle?

It is the Calvin Cycle.


Purpose of Calvin Cycle?

what is the purpose of the calvin cycle


Who worked with Calvin to discover the Calvin cycle?

The discovery of the Calvin cycle is credited to Melvin Calvin, James Bassham, and Andrew Benson. But really, they probably led a team of researchers at the University of Berkley, California. They probably also used information from other scientists experiments and findings. If you're looking for one specific person, it's probably Benson, who is known to have contributed heavily to the work leading to the discovery. Sometimes the Calvin Cycle is also known as the Calvin-Benson Cycle.


What are other names for the Calvin cycle?

The Calvin Cycle is also known as the Calvin-Benson Cycle, light-independent reaction, or the C3 Cycle.


The Calvin cycle is called a cycle because of what?

The Calvin cycle is a cycle because in the course of the cycle its starting material is regenerated.


Site for the Calvin cycle?

The Calvin cycle occurs in the stroma of chloroplasts.


Where is Calvin cycle occurring?

The Calvin cycle occurs in the stroma of chloroplasts.


Which organelle participates in the Calvin cycle?

Chloroplast contains the Calvin Cycle.


What molecule is regenerated in the Calvin cycle?

RuBP is regenerated in the Calvin Cycle.


Is glucose required for the Calvin cycle?

No. Calvin cycle is the cycle in plants that makes glucose, not requires them.


What does the word cycle tell about chemical reactions of the Calvin cycle?

the calvin cycle is very importnant


During what cycle are sugars produced in the chloroplast?

During The Calvin Cycle cycle, sugars are produced in the chloroplast.


Why is the Calvin cycle called a cycle?

The Calvin Cycle is called a cycle because it is a series of steps that repeat themselves continuously.


The Calvin cycle takes place in the?

The Calvin cycle takes place in the stroma.


What gas is used in the Calvin cycle?

carbon dioxide is used in the Calvin cycle.


Where does the Calvin cycle happen?

The Calvin cycle takes place in the stroma of chloroplasts.


Where does the Calvin cycle reaction occur?

The Calvin cycle occurs in the stroma of the chloroplast.


What occurs during Calvin cycle?

Photosynthesis occurs during the calvin cycle.


Where does the Calvin cycle occur in the chloroplast?

Calvin cycle occurs in the stroma of the chloroplast


Are nadph and ATP produced by the Calvin cycle?

No, NADPH and ATP are not produced by the Calvin Cycle. They are produced by the Light Reactions, and used during the Calvin Cycle.


What is the Calvin Cycle and who discovered it?

The Calvin Cycle is the cycle plants use to synthesize glucose from Carbon Dioxide. It was discovered by Melvin Calvin, who named it after himself.


What is melvin calvin famous for?

The Calvin Cycle


When does the Calvin cycle occur in most plants?

The Calvin Cycle is one of the light dependent reactions in plants. The Calvin Cycle occurs during the photosynthesis process.