Entropy as a novel determinant of photosynthetic structure and function

In this project, we explore the photosynthetic apparatus as a system where light energy interacts with living matter, subject to thermodynamic constraints of which entropy has been seldom studied.

Chloroplasts, the powerhouse of higher plants and recently-evolved green algae, almost invariably have a granal structure: flattened thylakoid sacs stacked up to form orderly grana, interconnected by non-stacked thylakoids and bathed in an aqueous stroma phase, all enclosed in a double-membrane envelope. Obviously, chloroplasts are an open system through which both energy and mass flow.
But why are grana so ubiquitous in the plant world? What is Nature’s driving force for selecting a granal structure? This research seeks to:

  • Demonstrate the involvement of entropy in thylakoid stacking, achieving order out of increased disorder.
  • Investigate the functional implications of entropy-assisted thylakoid stacking.
  • Establish that the functional consequences in turn enable chloroplasts to increase entropy production, a thermodynamic imperative.
  • Relate the evolution of a granal structure to the evolutionary increase in complexity, defined as the energy flow through an open system per unit time per unit mass.