Oxygen, that double edged sword.

[Rooser]

What is it about Oxygen. Without it the animal population of this planet would be screwed yet in the same way it is also the one doing the screwing. It erodes or reacts with virtually everthing it comes into contact with, we consume antioxidents for crying out loud. So why Oxygen, what does it do for the body that a nice inert gas couldn't? Why not nitrogen? there's loads of that and it doesn't do anything. Oxygen, it's just plain wrong.

[j2buttonsw]

Oxygen is used precisely because it is an oxidising agent (ie accepts electrons) and the oxidation of substrates is exothermic. Other oxidising agents can be used for respiration (eg sulphur) but none are as good as good old oxygen.

[Rooser]

Ok, cool, that sounds lovely and scientific, but why do we need to "accept electrons" does this then mean that my muscles that are in need of oxygen infact need only electrons? and what on earth does "oxidation of substrates is exothermic" mean in all this?

[rojash]

what on earth does "oxidation of substrates is exothermic" mean in all this?
It means it releases heat energy. We need energy to live.
Your original question is a bit like asking why the combustion engine uses a flammable liquid instead of something safe like water. The simple answer: because the combustibility is essential to the operation of the engine.

[ludwig]

You get too much you get too high - not enough and you're gonna die.

[jake-the-peg]

I'm not a biologist so bear with me if there are any inacuracies here.

Oxygen is required for the chemical reaction that synthesyses something called ATP. This is what is called Cellular respiration. The ATP cycle of reactions happens in the bit of every living cell called mitochondria and provides the energy for the cell to function.

Basically the in every cell of your body mitochondria act as furnaces reacating Oxygen with Glucose.

Now I suppose that it's conceivable that life on earth could have evolved to use some other chemical reaction to liberate energy but it needs to generate just enough energy and not too much and needs to be soluable in a liquid transport medium etc.

There may be more solutions other than Carbon and Water based with Oxygen but I wouldn't think there would be very many others. 

There might be a way to get a similar sytem running with Nitrogen and Ammonia for example but you'd not get a lot of energy from Helium say.

Now the real question to blow your mind is how mitochondria came to evolve - probably seperatly from primordial cells and how they came to be part of the cells that we are all made of.

Any biologists care to field that one?

[j2buttonsw]

I knew exothermic was wrong when I wrote it. I meant exogonic.

[Rooser]

THANK YOU!!! oh thank you jakethepeg. This is exactly the plain english answer I was after. As for mitochondria, who cares, it here and it works. And it sounds like you'd catch it by weeing in the wrong place in a jungle.

[Thunderchild]

as usual jake the peg has hit the nail on the head.

also bear in mind that what we call oxidation is simply the cemical reaction of oxigen it is harmful in the sense of metal but do u know the true name of water the chemical name ?: oxidised Hydrogen (maybe not perfect cause i did my chemistry in italian so i might not have translated exactly but i'm sure u get the point). we call it water because thats the everyday term and the one used before he chemical composition was know as for salt it's real name is clorum-sodiun and so for many other common products.

[neurosurgon*]

If im not much mistaken, oxygen also 'eats' some fatal deseses(sorry if i spelled it wrong) and so 0two is a protective measure.

[rowe21]

jake-the-peg, you make a lot of good points, but one or two things

in the process of respiration glucose and oxygen never come into contact with each other. In fact glucose goes through a number of processes, with one of the final products being the one that reacts with oxygen, so the old equation of respiration being referred to as

glucose + oxygen -->energy + water

is actually a load of rubbish.

and now on to the point of where mitochondrion come from. One of the most accepted theories of where they come from is that they were actually bacteria, engulfed by the host cell, but was kept intact. There are many similarities between mitochondria and bacteria, with the double membrane, the inner folding of the inner membrane, (aka cristae). Bearing in mind all of the above information is only a basic grasp os AS level biology, i apologise if any is incorrect, as I have not even sat my AS exams yet!!