Early life might not have been Green

Technocrat

Early life might not have been Green

zogger

Tue Apr 10 20:28:27 -0700 2007

Biology.

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The reflected green from chlorophyll powered plants might be an evolutionary step after purple. A researcher at the University of Maryland theorizes that earlier microbes might have been retinal based, which would have given them a purplish tint, as they absorbed the green part of the spectrum, but that latter plants using chlorophyll and the opposite ends of the spectrum for energy are chemically more efficient.

..."DasSarma thinks it is because chlorophyll appeared after another light-sensitive molecule called retinal was already present on early Earth. Retinal, today found in the plum-colored membrane of a photosynthetic microbe called halobacteria, absorbs green light and reflects back red and violet light, the combination of which appears purple."....more color choice there

ed: I think mowing a purple lawn might be interesting....for like three days or so. Something about green that is quite soothing, to me anyway.

So, use them both

wowbagger

Wed Apr 11 04:34:14 -0700 2007
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So what happens if you either
gengineer an algae with both chlorophyll and retinal
or
simply mix halobacteria and normal algae in a tank
and use them to capture sunlight and convert it into chemical energy? Would that not tend to increase the efficiency of such a system?

Early life might not have been Green

Bhima

Wed Apr 11 06:15:23 -0700 2007
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I have a real issue with the stereotypical American “Lawn” and the maniacal obsessives who perpetuate the infatuation. When I lived next to one in Atlanta suburbs a purple lawn which successfully and randomly spread into the adjoining properties would have made me positively orgasmic.

Early life might not have been Green

President4242

Wed Apr 11 09:06:01 -0700 2007
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Me too- but that's because I am in a suburb, but I'm slowly getting a yellow-green lawn- based on a native moss that I'm encouraging by leaving leaf raking for the spring instead of the fall. It seems to take little kid footprints better than any grass I've ever seen, and it never grows more than an inch high.

Early life might not have been Green

bi-ker-shi

Thu Apr 12 04:05:20 -0700 2007
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Photosynthesis is a lot more complicated than you might think. If retinal had a role to play in kick starting chlorophyll I doubt very much if it would survive for so long if it were not for some inherent advantage.

Photosynthesis actually has two separate systems called Photosynthesis 1 and Photosynthesis 2. Both rely on the energy of electrons knocked out of the chlorophyll by photons.

Photosynthesis 1 uses lower energy electrons from reddish photons, while Photosynthesis 2 uses the higher energy electrons from the blue end. These two systems operate in separate cellular structures and generally drive chemical reactions in boundary structures as the currents in the form of free protons pass through.

Photosynthesis 2 charges up to a higher voltage and so can drive chemical reactions that require more energy. Generally the end products from 1 run down hill energy-wise through a series of reactions, and are then kicked up higher by 2, to run downhill some more to the end product.

Think of it this way: if you have a photovoltaic cell, typically it can’t use photons below a set energy level, but can’t use all of the energy above this level. Technocrats are trying to overcome this limitation by layering different band gaps on top of each other, and by tricks that allow a high energy photon to kick out two photons at once. They have a long way to go to equal Chlorophyll when you consider the inevitable loss of energy transforming electricity to chemical energy.

Another evolutionary adaptation is that plants typically have various additional pigments that absorb photons in the yellow green range, and emit them back in the red. Thus these plants are actually a very dark green. No room left for a role for retinal.