What is calvin cycle

Here they enter red corpuscles as young malarial parasites, and the majority pass through the asexual cycle just described.

Still hanging to Clip's canteen, he jerked the motor-cycle away from the bushes, got into the saddle, and started the pedals. Matt went down, with the motor-cycle on top of him, head and shoulders over the brink of the precipice.

Matt had come to a quick stop, disengaging his right foot from the toe-clip and bracing the motor-cycle upright. New Word List Word List. Save This Word! At this point, only one of the G3P molecules leaves the Calvin cycle and is sent to the cytoplasm to contribute to the formation of other compounds needed by the plant.

But each turn makes two G3Ps, thus three turns make six G3Ps. One is exported while the remaining five G3P molecules remain in the cycle and are used to regenerate RuBP, which enables the system to prepare for more CO 2 to be fixed.

Three more molecules of ATP are used in these regeneration reactions. Learning Objectives Describe the Calvin Cycle. Key Points The Calvin cycle refers to the light-independent reactions in photosynthesis that take place in three key steps.

Although the Calvin Cycle is not directly dependent on light, it is indirectly dependent on light since the necessary energy carriers ATP and NADPH are products of light-dependent reactions.

In fixation, the first stage of the Calvin cycle, light-independent reactions are initiated; CO 2 is fixed from an inorganic to an organic molecule. Key Terms light-independent reaction : chemical reactions during photosynthesis that convert carbon dioxide and other compounds into glucose, taking place in the stroma rubisco : ribulose bisphosphate carboxylase a plant enzyme which catalyzes the fixing of atmospheric carbon dioxide during photosynthesis by catalyzing the reaction between carbon dioxide and RuBP ribulose bisphosphate : an organic substance that is involved in photosynthesis, reacts with carbon dioxide to form 3-PGA.

These energy-carrying molecules travel into the stroma where the Calvin cycle reactions take place. In plants, carbon dioxide CO 2 enters the chloroplast through the stomata and diffuses into the stroma of the chloroplast—the site of the Calvin cycle reactions where sugar is synthesized. The reactions are named after the scientist who discovered them, and reference the fact that the reactions function as a cycle.

Others call it the Calvin-Benson cycle to include the name of another scientist involved in its discovery Figure 1. The Calvin cycle reactions Figure 2 can be organized into three basic stages: fixation, reduction, and regeneration. RuBP has five atoms of carbon and a phosphate group on each end. This type of reaction is called a reduction reaction, because it involves the gain of electrons. A reduction is the gain of an electron by an atom or molecule. One of the G3P molecules leaves the Calvin cycle to contribute to the formation of the carbohydrate molecule, which is commonly glucose C 6 H 12 O 6.

Because the carbohydrate molecule has six carbon atoms, it takes six turns of the Calvin cycle to make one carbohydrate molecule one for each carbon dioxide molecule fixed. The remaining G3P molecules regenerate RuBP, which enables the system to prepare for the carbon-fixation step. Figure 2. The Calvin cycle has three stages. In stage 1, the enzyme RuBisCO incorporates carbon dioxide into an organic molecule. In stage 2, the organic molecule is reduced. In stage 3, RuBP, the molecule that starts the cycle, is regenerated so that the cycle can continue.

In summary, it takes six turns of the Calvin cycle to fix six carbon atoms from CO 2. Check out this animation of the Calvin cycle. Figure 3. Living in the harsh conditions of the desert has led plants like this cactus to evolve variations in reactions outside the Calvin cycle. These variations increase efficiency and help conserve water and energy.

The shared evolutionary history of all photosynthetic organisms is conspicuous, as the basic process has changed little over eras of time. Even between the giant tropical leaves in the rainforest and tiny cyanobacteria, the process and components of photosynthesis that use water as an electron donor remain largely the same.

Photosystems function to absorb light and use electron transport chains to convert energy. The Calvin cycle reactions assemble carbohydrate molecules with this energy. However, as with all biochemical pathways, a variety of conditions leads to varied adaptations that affect the basic pattern.