Johnson, Jane j3johnso at uwsp.edu
Thu Apr 24 08:42:45 EST 1997

Just one more comment on the photosynthesis terminology debate.  In the
Physiology text by Hopkins he uses Photosynthetic carbon reduction
reaction to refer to light independent/dark reactions.  The advantage is
that it is a accurate fairly accurate description of these reactions.
In my plant physiology class I introduce the terms light independent,
dark reactions and Calvin cycle in a historical context.  
I explain that both light independent and dark reactions  are misnomers
as the carbon reactions occur in the light and are dependent on the
light for the energy carrying molecules, and the regulation of RUBISCO
as well as glyceraldehyde 3-P dehydrogenase, fructose 1,6
bisphosphatase, sedohetulose,1,7-bisphosphatase and ribulose 5-P kinase.
The disadvantage to photosynthetic carbon reduction is that is
abbreviated it becomes PCR which could be confusing out of context.  

Someone suggested using CO2-fixing as a term to refer to these
photosynthetic carbon reaction, that may be acceptable for introductory
biology students but other non-photosynthetic reactions also can
carboxylate C.  Phosphoenolpyruvate carboxylase  fixs carbon in
non-photosynthetic pathways providing additional carbon for nitrogen
fixation and in malate production in guard cells.

The use of terminology should vary with the course taught I de-emphasize
the jargon in a non-majors course, but I expect the students in Plant
Physiology to have received a solid working vocabulary from there
introductory Botany and Zoology courses.  If we are training future
biologist I think it is reasonable and desirable that they learn the
terminology. If we are exposing students to Biology then  the minimum to
understand key concepts is probably all that is needed.

>Jane Johnson

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