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The Z-scheme

David Alan Walker d.a.walker at sheffield.ac.uk
Thu Apr 24 15:40:34 EST 2003

The Z-scheme came about by much combined effort but there is no doubt that
the paper by Hill R and Bendall F (1960)

 Function of the two cytochrome components in
chloroplasts: a working hypothesis. Nature Lond.,186, 136-137.

was a defining moment in photosynthesis. Indeed, one of the figures in that
paper looked like a 'Z' and lent its name to what has always since been
called the 'Z-scheme'.

It was not, however, a figure which immediately enhanced the understanding
of the average student with, perhaps, no more than a passing interest in
photosynthesis. Perhaps this is why a simplistic cartoon, created by Richard
Walker in 1979, has been endlessly reproduced, and its source less
frequently acknowledged, ever afterwards.

Most recently, stirred out of lethargy by an enquiry to 'plant ed', I have
recovered part of a Powerpoint presentation which I gave at the last
international Photosynthesis Congress (PS 2001) in Brisbane. Returning from
Oz on that occasion, via Monterey (where we visited my first mentor, Harry
Beevers) my wife and I were booked to fly on from LAX to Kennedy on
September 11th. Understandably, the awful events of that day put all manner
of things photosynthetic from my mind but I have finally managed to put
together a shortened version of my Brisbane PPt which includes not only the
Hill and Bendall figure, and the Richard Walker cartoon but an animated
version of the latter.

Conscious of viruses and the like I have, today, made this available for
download from the University of Sheffield, UK, which (at least in matters
digital) is about as pure as you can get. Should your interests lie in this
direction, you may find it at


It occupies about 1.4 MB

Comments, as always, would be appreciated.

>From David Walker, FRS., Emeritus Professor of Photosynthesis,
University of
Sheffield, UK.


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