Alright, this is a bit silly but....

[Morgyn]

Ok, so a friend in my biology class and I were discussing the most efficient way to get energy (eg. photosynthesis, cellular respiration etc.) and the question came up about why organisms other than plants don't utilise chloroplasts (I'm under the impression they were incorporated into a symbiotic relationship with plant cells like mitochondria) to get energy.

Then it got a bit ridiculous, with suggestions of taking a blastocyst (I think that's the one I mean, the ball of cells that makes a baby) and injecting the cell that would specialise into skin cells with choroplasts in order to make a photosynthesising human.

So, evidentally that's a rather unrealistic idea (not to mention slightly immoral), but it was more the earlier question of why plant cells are the smart kids who use choloplasts when we all use boring old glycolysis (ok, also, could we hypothetically make a photosynthesising human, I do want to know).

[alextemplet]

The idea's appeared in science fiction before:

http://starwars.wikia.com/wiki/Zelosian

It's not really fair to say that plants are smarter than heterotrophs; keep in mind that if heterotrophy wasn't a valid survival strategy then heterotrophs would've gone extinct a very long time ago and all life would be autotrophic. It is possible (in theory, at least) to inject chloroplasts into a human skin cell, but that would still leave the problem open of where to get nutrients. Plants have to use their roots for this, and are therefore very limited in how they choose their environment. In short, a seed grows where it falls, and if there isn't sufficient nutrients in that particular spot then it just doesn't grow at all. Animals are (usually) more mobile and at liberty to choose where they live; if one area isn't suitable, they can move somewhere else. This can be just as valuable of a survival strategy as being able to photosynthesize your own energy.

[Morgyn]

Yeah, but a photosynthesising human could move AND still eat (to get nutrients). Plus I was joking when I said it made them smarter (sorry to all the heterotrophic organisms out there), it was more of a query as to why there aren't really organisms that get their sustenance both ways (or are there...?)

Thanks for the link also, I'd never heard of wookieepedia, but I'm glad I have now

P.S. So with the nutrient problem sorted, can we make a photosynthesising human?

[mith]

You'd need to drink water like a horse. And you'd need way more surface area. Maybe form some symbiotic relationship with algae.