Photosynthesis, which uses energy from the Sun and carbon dioxide from the atmosphere to create carbohydrates, might be the most influential set of biochemical reactions on the planet.
Here's the problem. That's not a very good definition of photosynthesis. I discuss a much better definition in a post from seven years ago: Scientists confused about photosynthesis. A better definition is that photosynthesis is the process by which light energy is captured and converted to chemical energy. The direct products of photosynthesis are ATP and reducing equivalents such as NADPH. These cofactors are used to drive all sorts of reactions in the cell including DNA synthesis, protein synthesis, lipid synthesis, and carbohydrate synthesis.
1. I'm using the title from the printed version of the journal. The web version has a different title. (I don't know why.)
5 comments :
I'm willing to give Nature a pass on this one since the article is focused on carbohydrate production in cultivars. At the same time, reminding plant biologists about the variety of photosynthetic pathways in nature is never a bad thing.
@Anonymous What "variety of photosynthetic pathways" are you referring to? The most important ones that I know of are those in purple bacteria (photosystem II only) and green sulfur bacteria (photosystem I only).
Surely the 'purpose' of a plant (or photosynthetic bacterium) is to create other plants. Synthesizing simple carbohydrates, and subsequently DNA synthesis, protein synthesis, lipid synthesis, etc., is key. Without these a plant will not reproduce however well it can capture, store and use light energy. In this view, the primary innovation and success of photosynthesis, both anoxygenic and oxygenic, is to split hydrogen from other compounds for use in synthesizing carbohydrates, since carbon and oxygen are relatively abundant in the environment, while free hydrogen is not. Energy capture is then secondary.
@Henry Tarpal: The product of photosynthesis is ATP and, in some cases, NADPH. Those chemical cofactors are used in a variety of metabolic reactions. The fixation of carbon is one of those important reactions but, in most organisms, it's no more important, and no more essential, than all of the other reactions necessary to sustain life.
The fixation of carbon is common in all species. It can be the main source of carbon compounds in lots of non-photosynthetic species. In fact, some of them even use the Calvin cycle. This demonstrates that carbon fixation and photosynthesis are not linked and that makes a lot of sense since life evolved for several hundred billion years before photosynthesis arose.
Fixing CO2
https://sandwalk.blogspot.com/2014/10/fixing-co-2-fixation.html
I agree with your points about carbon fixation. My point is that photosynthesis (contrary to popular belief) may be about hydrogen fixation more than energy capture.
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