Des describe two phases of photosynthesise.
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What are the phases of photosynthesis?
Originally Answered: What are the phases of photosynthesis?
The Two Parts of Photosynthesis
Light-dependent and light-independent reactions are two successive reactions that occur during photosynthesis.
Key Points
In light-dependent reactions, the energy from sunlight is absorbed by chlorophyll and converted into chemical energy in the form of electron carrier molecules like ATP and NADPH.
Light energy is harnessed in Photosystems I and II, both of which are present in the thylakoid membranes of chloroplasts.
In light-independent reactions (the Calvin cycle), carbohydrate molecules are assembled from carbon dioxide using the chemical energy harvested during the light-dependent reactions.
Key Terms
photosystem: Either of two biochemical systems active in chloroplasts that are part of photosynthesis.
Photosynthesis takes place in two sequential stages:
The light-dependent reactions;
The light-independent reactions, or Calvin Cycle.
Light-Dependent Reactions
Just as the name implies, light-dependent reactions require sunlight. In the light-dependent reactions, energy from sunlight is absorbed by chlorophyll and converted into stored chemical energy, in the form of the electron carrier molecule NADPH (nicotinamide adenine dinucleotide phosphate) and the energy currency molecule ATP (adenosine triphosphate). The light-dependent reactions take place in the thylakoid membranes in the granum (stack of thylakoids), within the chloroplast.
The two stages of photosynthesis: Photosynthesis takes place in two stages: light-dependent reactions and the Calvin cycle (light-independent reactions). Light-dependent reactions, which take place in the thylakoid membrane, use light energy to make ATP and NADPH. The Calvin cycle, which takes place in the stroma, uses energy derived from these compounds to make GA3P from CO2.