The document defines and describes the Calvin cycle or C3 cycle, which is the set of chemical reactions that plants use to reduce carbon dioxide into glucose. It occurs in the chloroplasts of plant leaves. The three stages of the Calvin cycle are carbon fixation, reduction, and regeneration. Carbon fixation converts carbon dioxide into a 3-carbon compound. Reduction uses energy from ATP and NADPH to convert this into glyceraldehyde-3-phosphate. Regeneration regenerates RuBP from G3P and produces glucose. The overall process uses energy from light reactions to convert carbon dioxide into glucose as energy storage.

1. DARK REACTION
BY
BP221503
I- M.SCAPPLIEDMICROBIOLOGY
SACREDHEART COLLEGE (AUTONOMOUS)
TIRUPATTUR

2. DEFINITION
 “Calvin cycle or C3 Cycle is defined as a set of chemical reaction performed by the plants to reduce carbon
dioxide and other compounds into glucose.”
 Calvin cycle is also known as the C3 cycle or light-independent or dark reaction of photosynthesis
 This Calvin cycle takes place mainly in the leaf of a green plant more specifically in the stroma of the
chloroplast
 These plant that produce energy from Calvin cycle in the presence of light are known as photoautotrophs

3. STAGES OF DARK REACTION
The three stages of calvin cycle are
1.Carbon fixation
2.Reduction
3.Regeration

4. CARBON FIXATION
 It is a process wherein photosynthetic organisms turn inorganic carbon into
organic compound (carbohydrates)
 Carbon dioxide fixation is a type of carbon fixation where the carbon dioxide from the
atmosphere is converted into carbohydrate
 It is the first key step in this Calvin cycle
 This carbon fixation process occur during the light reaction phase of the Calvin cycle
because it require light to complete this segment of the cycle

5. REDUCTION
 The second stage of Calvin cycle is a Reduction stage. The 3-PGA molecules created
through carbon fixation are converted into molecules of simple sugar – glucose.
 This stage obtains energy from ATP and NADPH formed during the light-dependent
reactions of photosynthesis.
 Calvin cycle becomes a pathway in which plants convert sunlight energy into long-term
storage molecules, such as sugars. The energy from the ATP and NADPH is transferred to
the sugars.
 This step is known as reduction since electrons are transferred to 3-PGA molecules to
form glyceraldehyde-3 phosphate.

6. REGENERATION
 Regeneration is a third stage of the Calvin cycle and is a complex process that requires
ATP. In this stage G3P molecules are used to produce glucose,
 This third stage is known as regeneration because Ribulose Bis Phosphate that begins the
cycle is regenerated from glucose 3 phosphate

8. PRODUCTS OF CALVIN CYCLE
 one molecule of carbon is fixedat each turn of calvin cycle
 One molecule of glyceraldehyde three phosphate is created in three
turns of Calvin cycle
 Two molecule of glyceraldehyde three phosphate combine together to form one
glucose molecule
 3 ATP and 2NADPH molecule are used during the reduction of 3
phospho glyceric acid to glyceraldehyde 3 phosphate and in the
regeneration of RuBP.
 18 ATP and 12 NADPH are consumed in the production of 1
glucose molecule

9. References
1. https://byjus.com/biology/calvin-cycle
2. https://www.biologyonline.com/dictionary/carbon-fixation
3. https://unacademy.com/content/cbse-class-11/study-material/biology/calvin-
cycle/
4. https://www.turito.com/blog/biology/calvin-cycle