List and explain expensively the two process involved in photosynthetic reaction

Answer 1

The two processes involved in photosynthetic reaction are the light-dependent reactions and the light-independent reactions (also known as the Calvin cycle or the dark reactions).

1. Light-dependent reactions:
This process occurs in the thylakoid membranes of the chloroplasts. It involves the conversion of light energy into chemical energy in the form of ATP and NADPH. The main steps in the light-dependent reactions are:
- Light absorption: Chlorophyll and other pigments in the thylakoid membranes absorb light energy.
- Electron transport chain: Excited electrons from the chlorophyll molecules are passed along a series of protein complexes, releasing energy that is used to pump protons (H+) across the membrane into the thylakoid space.
- ATP synthesis: The buildup of protons in the thylakoid space leads to a concentration gradient, and the protons flow back through ATP synthase, a protein complex, which generates ATP from ADP and inorganic phosphate.
- NADPH synthesis: As the electrons pass through the electron transport chain, they are transferred to NADP+, converting it into NADPH, which carries high-energy electrons.

2. Light-independent reactions (Calvin cycle):
The light-independent reactions occur in the stroma of the chloroplasts, and they involve the conversion of carbon dioxide into glucose using the energy stored in ATP and NADPH produced during the light-dependent reactions. The main steps in the Calvin cycle are as follows:
- Carbon fixation: Carbon dioxide molecules are converted into a 3-carbon compound called 3-phosphoglycerate (PGA) using an enzyme called Rubisco.
- Reduction: ATP and NADPH from the light-dependent reactions are used to convert PGA into another 3-carbon compound called glyceraldehyde-3-phosphate (G3P).
- Regeneration: Some G3P molecules are used to regenerate the original compound that binds with carbon dioxide (RuBP), while others are used to produce glucose and other organic molecules.
- Recycling: ATP is required to regenerate RuBP so that the cycle can continue.

Overall, photosynthesis is a complex process that involves capturing and converting light energy into chemical energy, utilizing ATP and NADPH from the light-dependent reactions to convert carbon dioxide into glucose during the light-independent reactions (Calvin cycle).