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Where are the Atp and Nadph Used?

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The process by which plants convert carbon dioxide, water, and sunlight into oxygen and energy in the form of sugar is known as photosynthesis. Autotrophic plants produce their own food through a process called photosynthesis. Sunlight, chlorophyll, CO2, and water are four crucial components needed for this process. The two steps of photosynthesis are the Light Reaction and the Dark Reaction.

What is the ATP and NADPH? 

The products of the light reaction are ATP, NADPH, and O2. O2 diffuses from the chloroplast while ATP and NADPH power the reactions that create food, or more precisely, sugars. This is photosynthesis’s biosynthetic phase. In addition to CO2 and H2O, this process also depends on the products of the light reaction, ATP and NADPH, which are not directly dependent on the presence of light.

The biosynthetic step makes use of ATP and NADPH. As we previously observed, CO2 and H2O combine to form (CH2O)n, or sugars. The work of Melvin Calvin is outstanding. He discovered that the initial CO2 fixation product was a 3-carbon organic acid by using radioactive 14C in his research on algae photosynthesis. The entire metabolic route was developed and as a result, it was named the Calvin cycle in his honor. The initial item discovered was 3-phosphoglyceric acid or PGA.

The first stable byproduct of CO2 fixation was an organic acid once more, but this time it had four carbon atoms. Oxaloacetic acid, also known as OAA, was determined to be this acid. Since then, it has been believed that there are two primary types of plants that assimilate CO2 during photosynthesis: those in which a C3 acid (PGA), or the C3 pathway, is the first product of CO2 fixation, and those in which a C4 acid (OAA), or the C4 pathway, is the first product.

Primary acceptor of CO2

Ribulose 1,5 bisphosphate, also known as RUBP, is the main carbon dioxide acceptor in the dark process and is carboxylated by the enzyme ribulose 1,5 bisphosphate carboxylase oxygenase, also known as RuBisCo. As the first stable byproduct of the C3 cycle, this carboxylation results in the production of two molecules of the three-carbon chemical phosphoglyceric acid.

Calvin Cycle (C3 cycle) 

The Calvin cycle is also known as the C3 cycle, the nighttime reaction of photosynthesis, or the light-independent reaction. However, it is most active during the daytime when there is a surplus of ATP and NADPH. To build organic molecules, the plant cells use raw materials provided by light reactions.

Stages of Calvin Cycle

There are three stages of the Calvin cycle

Calvin Cycle


Carbon fixation: CO2 binds to RuBP to produce In the necessary procedure known as carbon fixation. Two to three carbon molecules of phosphoglycerate. Ribulose bisphosphate carboxylase/oxygenase, an enzyme with four subunits found in the stroma of chloroplasts, provides the catalyst for this reaction. By digesting roughly three molecules of RuBP per second, this enzyme functions exceedingly slowly. Over 50% of the protein in a normal leaf is RuBisCO. It is believed to be the protein that is most prevalent on earth.

Reduction: It’s Calvin’s cycle’s second phase. The 3-PGA molecules produced by carbon fixation are changed into glucose molecules, which are simple sugar molecules. ATP and NADPH produced during the photosynthesis’ light-dependent processes provide energy for this stage. Thus, the Calvin cycle becomes a process through which plants transform solar energy into molecules that can be stored for a long time, like sugars. The sugars receive the energy from the ATP and NADPH. Since electrons are transferred to 3-PGA molecules to create glyceraldehyde-3 phosphate, this process is known as reduction.

Regeneration: The Calvin cycle’s third stage is a difficult procedure that needs ATP. While others are recycled to regenerate the RuBP acceptor at this stage, some of the G3P molecules are utilized to create glucose.

Equation & Products of Calvin Cycle

6 NADPH + 9 ATP + 3CO2 + 5H2O —-> G3P + 2H+ + 6NADP+ + 9ADP + 8Pi

(G3P – Glyceraldehyde-3 phosphate ; Pi= Inorganic phosphate)

FAQs on the Uses of Atp and Nadph?

Question 1: What is Calvin Cycle? 


The C3 cycle is also called as Calvin cycle. The carbon from the carbon cycle gets fixed into sugars during a process of chemical reactions. It takes place in the plant cell’s chloroplast.

Question 2: What are the different phases of the Calvin cycle?


The different phases of the Calvin cycle are Reduction, regeneration, and carbon fixation. 

Question 3: What is the full form of NADPH? 


NADPH (nicotinamide adenine dinucleotide phosphate). 

Question 4: What are Light-independent reactions? 


This reaction occurs both in the presence and absence of sunlight.

Question 5: What is carbon fixation in the Calvin cycle?


RuBP reacts with CO2 to produce a six-carbon molecule, which is then split into two three-carbon compounds by the action of RuBisCO. Because CO2 is “fixed” from its inorganic state into organic molecules, this process is known as carbon fixation.

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Last Updated : 01 Dec, 2022
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