The Calvin Cycle: What Is It? What characteristics exist?

Calvin Cycle

Calvin Cycle Diagram Definition and Mechanism research tweet

Called the calvin cycle, this phase of photosynthesis takes place independently of light. The dark phase is also known by the names carbon dioxide reduction and carbon sequestration reactions. Organic food is created by processes that happen in the stroma of chloroplasts without the need for light. The calvin cycle is also known as the dark phase because direct light is not required. Temperature changes have a significant impact on the cycle because there are many enzymatic reactions going on at that time.
It would be appropriate to define the Calvin cycle as the process by which atmospheric carbon dioxide reacts with ATP and NADPH+H+ to produce simple sugars in order to provide a brief response to the question of what the Calvin cycle is.

What Causes the Calvin Cycle?

Despite having a straightforward structure, the Calvin cycle can be challenging to comprehend due to its complexity. In this cycle, atmospheric CO2 is used to first oxidize NADPH+H+. The 5-carbon RDP molecule is then added to by the rubisco enzyme using APT created in the light phase, and as a result of this addition, an unstable 6C intermediate compound is created. Following the formation of the PGA with 3C molecule from the intermediate compound, which is broken down by enzymes, NADPH and ATP continue to be consumed, and the PGAL molecule is formed.

While some of the PGAL molecules are converted into organic molecules like glucose, amino acids, and fatty acids, others are used to make RMP and RDP. The continuation of the cycle is made possible by these synthesized RMP and RDP molecules. Only 1 molecule of glucose can be produced during the Calvin cycle by consuming 18 ATP and 12 NADPH+H+.

What the Calvin Cycle has to offer

1. During the cycle, ETS, light, and chlorophyll do not function; instead, they occur in the stroma.
2. The Calvin cycle is used for the synthesis of organic molecules. During the dark phase of photosynthesis, bases and vitamins are also produced in addition to organic monomers.
3. Water does not undergo photolysis or photophosphorylation during the Calvin cycle; rather, dephosphorylation occurs.
4. In this phase, ATP and NADPH+H+ produced in the luminous phase are oxidized and perform crucial functions.
5. The ATP synthase enzyme is not active during the calvin cycle because ATP is oxidized. Temperature changes undoubtedly affect the cycle because of the high enzymatic activity.
6. CO2 taken from the air is used to make the carbon molecules of the compound with C that is created during the Calvin cycle.


It is not a requirement that all plants photosynthesize. For food, some plants live as parasites on other organisms. Plants with chloroplasts don’t always engage in photosynthesis. For photosynthesis to occur, chlorophyll is necessary. Chlorophyll indicates that photosynthesis is taking place in the plant. To balance the osmotic pressure and stop the plant from overswelling by absorbing water, the glucose created during photosynthesis is stored after being converted into starch.

Sweet Secret | National Geographic Society


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