Phases of Photosynthesis

Light reaction:

The  summary of the events of light reaction is as follows;

• When chlorophyll molecules absorb light, their energy level increases and their electrons are emitted.
• Electrons are passed to electron transport chain to produce ATP.
• Light also breaks water molecule (photolysis) and oxygen is released. The hydrogen atoms of water give electrons to chlorophyll and become ions.
• The electrons of chlorophyll, after the production of ATP, and the hydrogen ions of water are used for the reduction of NADP INTO NADPH.

Dark reaction (calvin cycle):

The details of dark reactions were discovered by Malvin Calvin and his colleagues at the university of California. The summary of the events of dark reaction, also known as Calvin cycle is as follows;

• Carbon dioxide molecules are combined with 5-carbon compounds to form temporary 6-carbon compounds, each of which splits into two 3-carbon compounds.

• The 3-carbon compounds are reduced to 3-carbon carbohydrates by using ATP and hydrogen from NADPH. The 3-carbon carbohydrates are used to manufacture glucose.

• The 3-carbon carbohydrates are also used to regenerate the original  5-carbon compounds. This steps also utilizes ATP.