Photosynthesis Mechanisms and Phases

Study Notes

Photosynthesis

Photosynthetic organisms use light energy to convert simple molecules into complex ones
Photoautotrophs are organisms that use photosynthesis to make food
Chemoautotrophs use inorganic molecules such as hydrogen sulfide, ammonia, hydrogen, elemental sulphur, etc., to make complex molecules

Mechanism of Photosynthesis

Photosynthesis occurs in two phases: light-dependent and light-independent
The light-dependent phase occurs in the thylakoid membrane and requires light energy
The light-independent phase occurs in the stroma and does not require light energy, but relies on ATP and NADPH from the light-dependent phase.

Light-Dependent Phase

The light-dependent phase is characterized by the absorption of light by photosynthetic pigments like chlorophyll.
Absorbed light energy splits water molecules (photolysis) into hydrogen, oxygen, and electrons.
Protons and electrons release during photolysis are used to create NADPH and ATP.

Light-Independent Phase

This phase is also known as the dark reaction or Calvin cycle.
It involves carbon fixation, where carbon dioxide is reduced using NADPH and catalyzed by the enzyme RuBisCO.
The light-dependent phase provides the energy (ATP) and reducing power (NADPH) required for the light-independent phase.

Description

Explore the fascinating process of photosynthesis, focusing on its phases: light-dependent and light-independent. Understand how organisms like photoautotrophs convert light energy into chemical energy, and learn about the role of chlorophyll and other pigments in these processes.