Resumen de Before the beginning
Some 4 billion years ago, somewhere in the mass of inert minerals and molecules that made up our wet, rocky planet, dead became alive. This was the most important chemical transformation ever to happen on Earth. Not only did it give rise to all the living things that have ever existed, it also altered the chemistry of the oceans, the land and the atmosphere above. If it hadn't happened, there would beno blue marble. That first chemical step towards life may be a lot closer than we thought. The new approach starts with modern life and works backwards. Formed of a tangle of proteins and a relative of DNA called RNA, ribosomes are molecular machines found inside every living cell. They do just one thing and do it well: they read the genetic code contained in DNA and use it to construct proteins. In essence, they are cellular robots that build the stuff that makes our cells tick
