Lecture Notes on Photosynthesis

Light Reaction

• Light Reaction: Occurs during the day, but it is also called 'Light Independent Reaction.'
• Byproducts: ATP, NADPH, Oxygen. These byproducts are used in the dark reaction.
• Process:
  • Electrons are excited in chlorophyll.
  • Water is split, forming hydrogen, electrons, and oxygen.
  • Oxygen is released into the atmosphere.

Dark Reaction (Calvin Cycle)

• Dark Reaction: Also called 'Light Independent Reaction.' It can occur both during day and night.
• Process:
  • Formation of glucose using CO2 and hydrogen.
  • ATP and NADPH are used to make glucose.
  • Formation of triose phosphate.
• Steps:
  1. Carboxylation: Combining CO2 with RUBP to form 3-phosphoglycerate.
  2. Reduction: Conversion of 3-phosphoglycerate into triose phosphate.
  3. Regeneration: Reconstruction of RUBP.

Important Information

• Calvin Cycle:
  • Discovered by Melvin Calvin.
  • Uses radioisotope tracer technique.
  • First Product: 3-phosphoglycerate (3-C compound).
• Use of ATP and NADPH:
  • 3 ATP and 2 NADPH are needed for 1 CO2.
  • 18 ATP and 12 NADPH are needed for the formation of glucose.
• CO2 Accepter: RUBP, a 5-carbon compound.

Other Aspects of Photosynthesis

• Light and Dark reactions are interdependent.
• ATP and NADPH produced in the light reaction are used in the dark reaction.
• Hydrogen and electrons are formed during the photolysis of water.

Note: These notes help in detailed understanding of the processes of light and dark reactions in photosynthesis and include critical points for exam preparation.