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The Calvin cycle, also known as the light-independent reactions, is a key part of photosynthesis. In this cycle, plants convert carbon dioxide and other compounds into glucose.
Calvin cycle depends on the energy provided by ATP and NADPH, which are generated during the light-dependent reactions of photosynthesis. There are three main phases in the Calvin cycle: carbon fixation, reduction phase, and regeneration of RuBP (ribulose bisphosphate).
During carbon fixation, CO2 is attached to a five-carbon sugar, RuBP, resulting in a six-carbon compound that immediately splits into two molecules of 3-phosphoglycerate. In the reduction phase, ATP and NADPH are used to convert 3-phosphoglycerate into G3P (glyceraldehyde-3-phosphate), a three-carbon sugar. Some G3P molecules exit the cycle to form glucose, while others are used to regenerate RuBP. Overall, the Calvin cycle must turn six times to produce one molecule of glucose, consuming 18 ATP and 12 NADPH in the process.

ATP (adenosine triphosphate) is often referred to as the 'energy currency' of the cell because it stores and transports chemical energy within cells. It consists of adenosine (adenine + ribose) and three phosphate groups.
When a cell needs energy, it breaks the bond between the second and third phosphate groups in ATP, releasing energy and forming ADP (adenosine diphosphate).
In the Calvin cycle, ATP provides the necessary energy to convert 3-phosphoglycerate into G3P. It also supplies energy for other cellular processes, making it essential for the synthesis of glucose. Without sufficient ATP, the Calvin cycle cannot proceed efficiently, and glucose production would be halted.

NADPH (nicotinamide adenine dinucleotide phosphate) acts as 'reducing power' in photosynthesis and other biosynthetic pathways. It carries electrons and energy required to drive various reduction reactions.
In the light-dependent reactions of photosynthesis, sunlight energy is used to generate NADPH from NADP+ and H+.
Within the Calvin cycle, NADPH provides the hydrogen and electrons needed to reduce 3-phosphoglycerate to G3P. This reduction step is crucial for converting inorganic carbon into organic molecules that can be used to form glucose. Overall, 12 NADPH molecules are consumed in the Calvin cycle to produce one glucose molecule.

Glucose synthesis is the ultimate goal of photosynthesis and occurs after several complex biochemical steps. Glucose (C6H12O6) is a six-carbon sugar that serves as an essential energy source and metabolic intermediate for plants and other organisms.
During photosynthesis, light energy is converted into chemical energy through processes occurring in chloroplasts. The Calvin cycle produces G3P, which can then be used to form glucose.
As the Calvin cycle runs six times, it eventually constructs one glucose molecule from two three-carbon G3P molecules. This requires specific energy input, namely 18 molecules of ATP and 12 molecules of NADPH. Glucose not only provides energy for plants but also serves as a building block for cellulose, which is the main component of cell walls, and starch, used for energy storage. Thus, glucose synthesis is vital for plant growth, reproduction, and survival.