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The Dark side of Photosynthesis - The Calvin Cycle

The Calvin Cycle or the light-independent (dark) reactions of photosythesis.

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Calvin Cycle | Definition of Calvin Cycle by Merriam …

NADPH2 and ATP stem, as we will see, fromthe light reactions of photosynthesis in which the light energyis converted into chemical energy.

The Calvin cycle, or the light-independent (dark) reactions of photosythesis.

Calvin Cycle: (Also referred as – Light–Independent Reactions of Photosynthesis, Carbon Fixation) The high–energy molecules ATP and NADPH, synthesized in the light–dependent reactions of photosynthesis, are used to synthesize carbohydrates from carbon dioxide – hence the term carbon fixation.

Dark Reaction carbon fixation Calvin cycle Regeneration …

The first stable product of the Calvin Cycle is phosphoglycerate (PGA), a 3-C chemical

The production of ribulose diphosphate is best described by acycle (the CALVIN cycle), while the assimilate production is alinear process. It is based on the fact that an intermediate ofthe CALVIN cycle is deducted from it.

Phase III Regeneration of the CO2 acceptor (RuBP) : In a complex series of reactions, the carbon skeletons of five molecules G3P are rearranged by the last steps of the Calvin cycle into three molecules of RuBP. To accomplish this, the cycle spends three more molecules of ATP. The RuBP is now prepared to receive CO2 again, and the cycle continues. For the net synthesis of one G3P molecule, the Calvin cycle consumes a total of nine molecules of ATP and six molecules of NADPH. The light reactions regenerate the ATP and NADPH. The G3P spun off from the Calvin cycle becomes the starting material for metabolic pathways that synthesize other organic compounds, including glucose and other carbohydrates. Neither the light reactions nor the Calvin cycle alone can make sugar from CO2 . Photosynthesis is an emergent property of the intact chloroplast, which integrates the two stages of photosynthesis.

independent reactions is also known as the Calvin Cycle or Calvin ..

The plant performs the reactions in the Calvin-Benson cycle to produce the sugar glucose.

Phase I: Carbon fixation. The Calvin cycle incorporates each CO2 molecule, one at a time, by attaching it to a five–carbon sugar named ribulose bisphosphate (RuBP). The enzyme that catalyzes this first step is RuBP carboxylase, or rubisco. (It is the most abundant protein in the chloroplast and probably the most abundant protein on Earth). The product of the reaction is a six–carbon intermediate, so unstable that it immediately splits in half, forming two molecules of 3–phospoglycerate ( for each CO2 ).

Carbon enters the Calvin cycle in the form of CO2 and leaves in the form of sugar. The cycle spends ATP as an energy source and consumes NADPH as reducing power for adding high–energy electrons to make the sugar. The carbohydrate produced directly from the Calvin cycle is actually not glucose, but a three–carbon sugar named glyceraldehyde–3–phosphate (G3P). For the net synthesis of one molecule of this sugar, the cycle must take place three times, fixing three molecules of CO2 . As we trace the steps of the cycle, keep in mind that we are following three molecules of CO2 through the reactions.

10/08/2007 · Canu explain dark reaction (Calvin cycle) in photosynthesis
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  • The Calvin Cycle or 'Dark' Reactions (Photosynthesis)

    The light-independent reactions, or dark reactions, of photosynthesis are chemical reactions that convert carbon ..

  • Second animation of the Calvin Cycle - Smith College

    BioCoach Activity Concept 8: Cooperation of the Light Reactions and the Calvin Cycle


    Which of the following reactions ensures that the Calvin cycle can make a ..

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Notes on the C4 Cycle of Dark Reaction of Photosynthesis

In the photosynthesis takes place in a chloroplast of a thin-walled mesophyll cell and a 4-carbon acid is handed off to a thick-walled bundle sheath cell where the Calvin cycle occurs in a chloroplast of that second cell. This protects the Calvin cycle from the effects of .

Light-independent reactions Calvin cycle

Dark reactions make use of these organic energy molecules (ATP and NADPH). This reaction cycle is also called Calvin Benison Cycle, and it occurs in the stroma. ATP provides the energy while NADPH provides the electrons required to fix the CO2 (carbon dioxide) into carbohydrates.

The reactions of the Calvin cycle use the energy stored in the ..

The Calvin cycle is a reductive process in the stroma of chloroplasts responsible for the synthesis of carbohydrates from carbon dioxide. The reactions are organized in a cyclic metabolic pathway that was named after its discoverer Melvin Calvin who received the Nobel Price for Chemistry in 1961. Reducing power in the form of NADPH (nicotinamide‐adenine dinucleotide phosphate reduced form) and energy as adenosine triphosphate (ATP) required for this process are generated in the light reactions located in the thylakoid membrane. Light activation of this process is achieved by covalent redox‐modification of some key enzymes that are inactive in the dark.


Carbon dioxide is captured in a cycle of reactions known as the Calvin cycle or the Calvin-Benson cycle after its discoverers. It is also known as just the C3 cycle. Those plants that utilize just the Calvin cycle for carbon fixation are known as . Carbon dioxide diffuses into the stroma of chloroplasts and combines with a five-carbon sugar, ribulose1,5-biphosphate (). The enzyme that catalyzes this reaction is referred to as , a large molecule that may be the most abundant organic molecule on the Earth. This catalyzed reaction produces a 6-carbon intermediate which decays almost immediately to form two molecules of the 3-carbon compound 3-phosphoglyceric acid (). The fact that this 3-carbon molecule is the first stable product of photosynthesis leads to the practice of calling this cycle the C3 cycle.

Light and dark reactions in photosynthesis - eschooltoday

The carbon fixation cycle, also called the Calvin cycle, is a 3–phase cycle that occurs in the stroma and that converts CO2 into carbohydrates using the energy of ATP and the oxidation of NADPH.

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