Science Questions

How was the first organic molecule made?

Sun, 16th Jan 2011

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David Whalley asked:

How was the first organic molecule made? Cheers


Chris -   I presume, he means in space with the evolution of the Universe or at least letís assume that's what he means because that's kind of interesting. 

Well this was a question that scientists struggled with for a very long time, including quite a famous scientist Stanley Miller who did the really famous Miller experiments in the 1950s, Ď60s, Ď70s.  And one of the things that he was intrigued by is the possibility that the complex life on Earth all arose from building blocks that were built up to make complex chemicals in situ here on the Earth in the early days of the planetís history.  And he did a very exciting experiment and Ben Valsler and I went to the University of California, San Diego to meet Jeff Bader who worked with Stanley Miller and has all of his equipment and in fact, all of the results of his experiments which he found in a laboratory at Stanley Millerís laboratory when he cleared out when Stanley Miller died.  That experiment consisted of taking a glass flask, putting in a source of hydrogen and carbon, and a source of nitrogen and some water, and mixing up those gases in the absence of oxygen in this flask, and heating it up to a very high temperature so it boiled off and then passing the vapours past a spark created between two electrodes. 

He ran this thing for about a week or so and what started off as a clear fluid in the bottom of the flask soon became chocolatey-brown. And when he analysed the products, he found at least 20 different chemicals.  When Jeff Bader re-analysed all of the chemicals that were in there about 20 years later using a mass spectrometer and very modern techniques, he found there were hundreds of complex organic chemicals in this mixture. 

So, in terms of the early Earth and probably the early Universe, what this experiment suggests is that you can make quite complicated, quite big molecules including the building blocks of life, amino acids, by recreating these conditions and having a source of energy, ionising radiation perhaps, and all those key molecules, and you can then get some exciting chemistry happening which will produce a range of different things.  So I think basically, itís not that difficult is what this is saying.

Dave -   Yes, since then people have found these complicated organic molecules all over the Universe.  They found them in meteorites, they've found evidence for them in big molecular clouds floating out in space as you huge clouds which are mostly made up of ethanol out there, which will be an alcoholicís paradise. 

So basically, all you need is some of the right kind of elements: some carbon, some oxygen, some nitrogen and some hydrogen, and something of about the right temperature, and some Ė as Chris was saying a source of energy, some ultraviolet light kicking about, not too much, just the right amount. 

And so, the first time in the Universe history when that's going to have been common is after there has been some big supernovae, because supernovae make the heavier elements.  Before then, it was mostly hydrogen.  There might been a few created just from the Big Bang, but the numbers will have been absolutely minute.  So you just need some supernovae to have gone bang and then stars starting up from their remnants.

So a couple of billion years after the Big Bang and I'm sure there were lots and lots of organic molecules kicking about.

Sarah -   And of course, I suppose by organic here, we don't mean sort of like the organic vegetables that you find in your supermarket and havenít been grown with pesticides.  We just mean molecules that have carbon in them.

Dave -   Yes and of course, obviously, the simplest organic molecule is something like methane with just some carbon and some hydrogen in it.


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