The light independent reaction

The Calvin Cycle A bit of background information

Calvin Cycle - The Light Independent Reaction Calvin's photosynthesis work began in On the day the Japanese surrendered, Ernest Lawrence told Calvin that it was "time to do something useful" with carbon-14. Calvin set about organizing a team of researchers to solve the riddle of photosynthesis. Calvin in his laboratory

Developing the new tracer technology as they went, he and his team traced the paths that carbon-14 travels through a plant during photosynthesis, starting from its absorption as labelled atmospheric carbon dioxide to its conversion into carbohydrates and other organic compounds. The old Radiation Laboratory

In resolving the many intermediate steps in the process, the Calvin team showed that, rather than acting directly on carbon dioxide as had been believed previously, sunlight energy is first captured by the plant's chlorophyll, ultimately to fuel the synthesis of organic compounds.

The Light Independent Reaction – also called the Calvin Cycle) This uses the ATP and NADPH from the light dependent reaction. It occurs in the stroma. It requires carbon dioxide which diffuses into the stroma along a concentration gradient, and a molecule of Ribulose BisPhosphate (RuBP) NB your syllabus and exam will probably refer to this as ribulose biphosphate – it’s the same thing!

Ribulose BisPhosphate RuBP Glycerate-3-phosphate GP Triose phosphate (also known as GALP or Glyceraldehyde Phosphate) 5C Carbon dioxide 2 x 3C NADPH NADP 3C Some is used to produce 6-carbon sugars and other organic substances ATP ADP PiPi ATP ADP PiPi The rest is converted back into RuBP

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