At dawn they grow fingers

When the light vanishes, the fingers retract

 Plankton Chronicles video by Christian Sardet et al.

Image: MARPLAN/John Dolan

Slightly out of tune

Although the chlorophyll molecules in the special pair are identical, they are embedded in different environments in the protein scaffold, which makes them vibrate at slight different frequencies: they are slightly out of tune...This structure provides photosynthetic reaction centres with the precise molecular architecture needed for them to work as quantum heat engines...Chlorophyll's special pair appears to be tuned to exploit quantum interference to inhibit inefficient wasteful energy routes and thereby deliver energy to the acceptor molecule with an efficiency that exceeds the...Carnot limit by...18 [to] 27 percent.

from Life on the Edge: The Coming Age of Quantum Biology by Jim Al-Khalili and Johnjoe McFadden (2014), citing Photosynthetic reaction center as a quantum heat engine.

Image: NHM

"A great part of our dignity"

Surely this is a great part of our dignity . . . that we can know, and that through us matter can know itself; that beginning with protons and electrons, out of the womb of time and the vastness of space, we can begin to understand; that organized as in us, the hydrogen, the carbon, the nitrogen, the oxygen, those 16 to 21 elements, the water, the sunlight — all, having become us, can begin to understand what they are, and how they came to be.

— George Wald (1964)

The more we learn, the more we are — or ought to be — dumbfounded.

— Lewis Thomas (1983)


Image: Plant cells with visible chloroplasts from a moss Plagiomnium affine, Kristian Peters. There can be around 50 chloroplasts in a typical plant cell. A square millimetre of leaf may contain 450,000 to 800,000 chloroplasts.

All possible paths simultaneously

Below you lies just one of the trillions of photosynthetic machines that manufacture the world's biomass [some 16,000 tonnes every second]. From your vantage point you can see that...although there are plenty of billiard-ball like turbulent molecular collisions going on, there is also an impressive degree of order. The membranous surfaces of the thylakoid is studded with craggy green islands forested with tree-like structures terminating in antennae-like pentagonal plates. These...are light harvesting molecules call chromophores, of which chlorophyl is the most famous example.

from Life on the Edge: the Coming Age of Quantum Biology by Jim Al-Khalili and Johnjoe McFadden (2014)

The very best photovoltaic cells...convert sunlight to electrical energy with an efficiency of around 35%; for more affordable cells the figure is closer to 20%. Plants accomplish the same process with about 90% efficiency during the first stage of photosynthesis. 

Efficiently converting light into electricity requires preserving the energy of an exciton [an electron-ion pair] as it travels deep within reaction centre of the leaf [and] the key to [this] lies in way it travels to the reaction centre. Researchers discovered to their great surprise in 2007 that plants use a [trick] from the realm of quantum physics to help excitons find their way. Rather than bumping randomly through a forest of chlorophyll molecules until they happen to reach their destination...each exciton spreads out over all possible paths simultaneously, and then funnels down through the most efficient route.

from How plants exploit sunlight so efficiently, The Economist.

Image from synechocystis.asu.edu