Chlorophyll under strange new stars.

[Gallowglacht]

One for the biology experts.

What colours of Chlorophyll in plants would work best in the light of other type stars? What type of light would make red chlorophyll more common in plants?

 

[Golan2072]

Red photosynthetic pigments are best at absorbing blue light.

 

[Gallowglacht]

Thank you!

 

[G. Fieendish]

Re:This thread
How about a black version of Chorophyll, for planets orbiting very dim red dwarf stars (M-Class)....?

 

[Thuban]

This article in Astrobiology describes possible photosynthetic pigment colors for autotrophic organisms living on planets orbiting F-, G-, K-, and M-class stars. The results are summarized on this web page.

There is also the "purple Earth theory" described here, which is based on the retinal molecule in the bacteriorhodopsin protein pump used by halobacteria.

Remember you can also use chemosynthetic autotrophs as primary producers as well.

 

[Gallowglacht]

Nice. Thanks for the input. So a little more variety for my players.

 

[Vargas]

Remember you can also use chemosynthetic autotrophs as primary producers as well.

Use them, I can barely pronounce them.

 

[aramis]

In case you need to know, chemosynthetic autotrophs use chemical reactions to produce energy from non-living matter. Like the microbes upon which the food cycles of the mid-ocean rifts. No light needed, only a chemical soup solution and sufficient heat.

 

[Thuban]

Use them, I can barely pronounce them.

An autotroph is an organism that produces its own food. A heterotroph is an organism that consumes organic material from other organisms. A mixotroph possess attributes of both auto- and heterotrophs.

A photosynthetic autotroph uses sunlight as an energy source to produce carbohydrates - terrestrial examples are plants and algae. A chemosynthetic autotroph uses the energy contained in inorganic chemical bonds to produce carbohydrates - terrestrial examples include bacteria around hydrothermal vents and cold seeps on the sea floor.

IMTU there are "radiosynthetic autotrophs" that use the decay of radioactive elements as an energy source and "plasmosythetic autotrophs" that use charged particles from the stellar wind as an energy source for producing food.

 

[aramis]

Mine, too, Thuban, Mine, too.

 

[Stainless]

Thuban's pretty well got it. There are two concepts to consider;
i) Where do I get my energy from?
ii) Where do I get my carbon from?

For i) there are 3 options;
a) Chemotrophs get their energy from organic molecules that have been synthesised by other living creatures. These can be pretty simple compounds like acetate or quite complex like baked beans on potatoes.
b) Chemolithotrophs get their energy from inorganic compounds or hydrogen. Commonly energy can be extracted from elemental sulfur, sulfate, sulfide, ammonia, etc. As the name connotes, these bugs can live off of rocks.
c) Phototrophs get their energy from light (not necessarily in the visible spectrum).

For ii) there are 2 options;
a) Heterotrophs get their carbon from organic molecules, regardless of where they get their energy from. Thus, an organism can be a chemolithoheterotroph.
b) Autotrophs 'fix' their carbon from simple sources such as carbon dioxide or carbon monoxide. Thus, an organism could be a chemoautotroph.

Something describes as being photosynthetic strictly speaking means it gets it's energy from light and fixes its carbon, usually, from carbon dioxide. i.e., it is a photoautotroph.

My favourite part conversation word is "chemolithoautotroph".

Then there's "obligate" and "facultative" but I'll leave that for another day.

Last thing to note is that chlorophyl is only one of the photoreceptor pigments that Life uses. It is used by cyanobacteria and in the chloroplasts of plants. Many other chemicals are used by different organisms. So it's better to refer to "photoreceptor pigments".

 

[Renaissance Man]

Is it true that chlorophyll is chemically identical to hemoglobin with the exception of one atom? I heard that from somebody. I think he said hemoglobin has iron and chlorophyll has magnesium...

 

[tjoneslo]

Yes and no. Yes, the core of both Heme groups and chlorophyll is a large heterocyclic organic ring called a porphyrin. Porphyrin consists of a flat circle of carbon/hydrogen atoms, holding four nitrogen atoms , which in turn hold a single atom. In the case of Heme groups this is an Iron atom, and Chlorophyll is it magnesium.

No it's not true in the sense that Chlorophyll then takes the Porphyrin and adds several large chains of carbon on for better handling, whereas the Heme group becomes part of the Hemoglobin, a large and complex protein with four heme groups on it.

 

[Renaissance Man]

No it's not true in the sense that Chlorophyll then takes the Porphyrin and adds several large chains of carbon on for better handling, whereas the Heme group becomes part of the Hemoglobin, a large and complex protein with four heme groups on it.

Interesting. I wonder why the similarity? I mean, the functions of hemoglobin and chlorophyll are pretty different. Sounds like porphyrin is a pretty useful molecule for respiration.

 

[tjoneslo]

The porphyrin isn't used for respiration in the chlorophyll, the Magnesium is what captures the photon, which then kicks out the electric charge, which is then used elsewhere in the plant to split CO2 and capture the carbon.

The porphyrin serves as a useful way to capture, hold, and use non-organic atoms. Organic material consists of combinations of four atoms: Hydrogen, Carbon, Oxygen and Nitrogen. So if your biological process relies upon another kind of atom, you need a way to manipulate it.

The atom in the center of the porphyrin ring isn't chemically bound there, it's more like held in a cage by the Nitrogen atoms. This allows it to do things like bind and release oxygen on command, or capture photons and release the electrons to power other biological processes.

The fact that both of them look the same is also a case of evolution in action. It's relatively simple to build a porphyrin ring from six carbon rings and the attached Nitrogen atoms. So simple + useful = multiple uses.

 

[Renaissance Man]

The porphyrin serves as a useful way to capture, hold, and use non-organic atoms. Organic material consists of combinations of four atoms: Hydrogen, Carbon, Oxygen and Nitrogen. So if your biological process relies upon another kind of atom, you need a way to manipulate it.

Thanks guys. Simple, and to the point. I wish I had a degree in organic chemistry or molecular biology. I'm going to need it to understand most of the new technological advances coming in the couple of decades.

 

[atpollard]

Not to derail the topic, but to push beyond Organic Chemistry:

I recenly read about Boron (Borane) and it's ability to form carbon-like chains and rings that generated 3D molecules similar to the complex carbon molecules. That suggests (to me) the posibility of a non-carbon based ecosystem with even stranger 'Chlorophyll'.

 

[BlackBat242]

I seem to remember Anne McCaffery having boron-based organics in some of her books? Like the Pern series?

 

[tjoneslo]

I recently read about Boron (Borane) and it's ability to form carbon-like chains and rings that generated 3D molecules similar to the complex carbon molecules. That suggests (to me) the possibility of a non-carbon based ecosystem with even stranger 'Chlorophyll'.

A big part of the reason that organic molecules use carbon, hydrogen, oxygen and nitrogen is their relative abundance, in relation to other elements. Borane doesn't occur naturally because boron aggressively oxidizes. But if your world has doesn't have enough free oxygen to destroy the borane chains, it may work. I'd probably substitute Sulfur and Phosphorous for the Nitrogen/Oxygen. There would also need to be a water equivalent.

But this would make for a weird (read: interesting) biochemistry system.

 

[atpollard]

tjoneslo,
Thanks for the data.

I was originally thinking of a 'water world' with one of those high numbered atmospheres having life in the toxic oceans. I was under the impression that carbon based life is also the SOURCE of most of Earth's free oxygen (plants stealing carbon from CO2).

A Boron-Hydrogen-Sulfur-Phosphorous dominated environment?
It sounds like a place VERY hostile and toxic to human life.