Photosynthesis: Light-Dependent & Independent Reactions

Photosynthesis Structure and Components

• Thylakoids are sac-like photosynthetic membranes found in chloroplasts, organized in stacks.
• Granum refers to a stack of thylakoids, essential for the light-dependent reactions of photosynthesis.
• Stroma is the fluid-filled space outside thylakoid membranes in chloroplasts, where the Calvin Cycle occurs.

Light-Dependent Reactions

• Light-dependent reactions utilize energy from light and water to generate ATP (energy currency) and oxygen, which is released into the atmosphere.
• These reactions occur within the thylakoid membranes of chloroplasts, where chlorophyll absorbs light energy.

Light-Independent Reactions (Calvin Cycle)

• The Calvin Cycle, also known as light-independent reactions or named after Melvin Calvin, uses ATP and carbon dioxide (CO2) to synthesize high-energy sugars, like glucose.
• The Calvin Cycle takes place in the stroma of chloroplasts.

Photosynthesis Requirements and Outputs

• Key molecules required for photosynthesis are carbon dioxide (CO2) and water (H2O).
• Products of photosynthesis include glucose and oxygen, serving as energy sources for plants and oxygen for living organisms.

Role of ATP

• ATP provides essential energy for various cellular reactions, enabling metabolic processes in living organisms.

Factors Influencing Photosynthesis

• Effective photosynthesis is influenced by several factors including:
  • Type of light and pigments present in plant cells.
  • Amount and intensity of light exposure.
  • Availability and abundance of CO2.
  • Source and abundance of water (H2O).
  • Environmental conditions such as temperature and pH.

Key Pigment in Photosynthesis

• Chlorophyll is the pigment responsible for the green color in plants, crucial for absorbing light energy during photosynthesis.

Summary of Photosynthesis Processes

• Light-dependent reactions produce ATP and oxygen using light energy and water.
• The Calvin Cycle synthesizes glucose using ATP and CO2, highlighting the interconnectedness of these processes in photosynthesis.