Fixing terminology

sctkr at sctkr at
Tue Apr 22 03:37:28 EST 1997

On 21 Apr 1997 08:52:14 -0700 Ken Klemow <kklemow at> wrote:
>Ross Konig wrote:
>>There are many words that need to be fixed in plant
>>physiology in similar ways (photoperiodism is usually
>>noctoperiodism, abscisic acid should have been named dormin,
>>dark reactions can only operate in daylight, etc.).
>One of my own pet peeves with terminology involves photosynthesis.  I
>despise the terms "light" and "dark" reactions because it gives students an
>erroneous feel for what is happening.  Instead, I prefer the terms
>"light-dependent" vs "light-independent" phases, and indeed have taught
>those terms to my students for the past dozen years.
>Kenneth M Klemow, Ph.D.

Can I throw my 'tuppence worth'  regarding light/dark reactions and light 
independent etc.

I do think terminology is important and tend to use, for these reactions, the Calvin 
or Calvin-Benson cycle with some explanation to the students regarding the 
dark/light problems including light independent which is also misleading.
1. pH optimum of Rubisco is about 8, achieved in the stroma by the 'light reactions' 
proton pumping into lumen.
2. RubisCO-activase pH, Mg2+ levels and ATP also 'light driven', pH above, Mg as 
balancing ion.
3. RubisCO-inhibitor, a sugar alcohol broken down (PSII) in light
4. RubisCO synthesis, light control of transcription for sub-units
I think
best wishes

Dr Kevin Reiling
Division of Biology
Staffordshire University

01782 294746

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