Entropy as a novel determinant of photosynthetic structure and function

Prof. (Fred) W.S. Chow (see ISI Highly Cited)
in association with Prof. Jan M. Anderson FRS, FAA (see ISI Highly Cited)

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 project seeks to (1) demonstrate the involvement of disorder (entropy) in thylakoid stacking, (2) investigate the functional implications of entropy-assisted thylakoid stacking, (3) establish that the functional consequences in turn enable chloroplasts to increase entropy production, a thermodynamic imperative, and (4) 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.

See illustration.

Techniques:    
kinetic in vivo optical spectrophotometry; chlorophyll fluorescence techniques; electron microscopy; biochemical techniques; oxygen measurements.

References:
Chow WS, Kim E-H, Horton P and Anderson JM (2005) Stacking of thylakoid membranes in chloroplasts: the physicochemical forces at work and the functional consequences that ensue. Photochemical & Photobiological Sciences 4: 1081-1090

Kim E-H, Chow WS, Horton P and Anderson JM (2005) Entropy-assisted stacking of thylakoid membranes. Biochimica et Biophysica Acta 1708: 187-195

Chow WS (1999) Grana formation: entropy-assisted local order in chloroplasts?  Australian Journal of Plant Physiology26: 641-647

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