Talk:C4 carbon fixation
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[edit] Rewrite
This article isn't as good as it could be. I'm gonna try a basic rewrite. I got pretty far now, but I'm tired. I'll come back later and finish if no one else does in the meantime. This is an important adaptive strategy, and the quality of the article should reflect it! GuildNavigator84 12:05, 22 May 2006 (UTC)
[edit] Photorespiration
The cuurent article states, "But since otherwise tropical plants lose more than half of photosynthetic carbon in photorespiration, the C4 pathway is an adaptive mechanism for minimizing the loss." Does anyone have a citation for this? Often 25% is used as a hand-waving average number. Falkowski and Raven's book state, "In terrestrial C3 plants, which rely purely on diffusive CO2 suuply to Rubisco, photorespiratory consumption of O2 can easily be 25% of the activity of the enzyme in vivo (see Raven 1984)." 216.59.224.253 16:35, 30 June 2006 (UTC)
Yes. As far as I understand it: in a few experiments, photorespiration has resulted in the loss of up to 50% of fixed carbon. However, this was not the norm, as that sentence suggests. I think that 30% loss is above average, and is considered a bad day. The losses are significant, however, and cut two ways-- every time you photorespirate, you miss out on that opportunity for photosynthesis, so there's an opportunity cost of carbon fixation. However, there is also the additional cost that you have to use previously fixed carbon products to undo the results of the photorespiration, which makes it even worse. Gcolive 03:29, 1 August 2006 (UTC)
