Cell. Part 3, The spark of life.

The last in a three-part series in which biologist Adam Rutherford looks in depth at cells. In this part Rutherford looks back to some of the earliest evidence of life on earth, over 500,000,000 years ago; fossilised cells. He then takes us to the present day in which scientists, such as Stephen del Cardayre, are on the brink of creating cells from scratch - Cardayre demonstrates his work in this field. In between, we look at the influence of Darwin's theory of evolution and the discovery of Aleksandr Oparin and John Haldane in the 1920s who were the first people to put forward a comprehensive theory as to how the first cell life came about, now known as the Oparin-Haldane Hypothesis. In 1952 US, Stanley Miller, fascinated by this hypothesis, attempted to recreate a primordial soup in which he found five key amino acids - for this he became a celebrity. Just years later Francis Crick and James Watson added the missing pieces to the puzzle when they discovered the structure of DNA. By the 1970s, geneticists could isolate individual genes to ascertain which proteins they made, allowing the inner workings of the cell to be changed. Contemporary work by astrobiologist Zita Martins at Imperial College London is shown; she describes how elements of our genetic code have been found in billions of years old meteorite rock samples; but the question remains as to how the earliest cells came together to form life. Jack Szostak attempts to recreate the way in which the first cell membranes were formed 4 billion years ago. He demonstrates this using fatty acid molecules which group together to form protocells. But protocells are not alive and one of the next goals in this field is to work out how to make such groups of chemicals come to life. Building cells from scratch is where biology meets engineering and a new field has been named: synthetic biology (synbio). Professor George Church at Harvard Medical School is using computers and genetics to analyse some of the thousands of components of living cells in order to attempt to create a synthetic cell; Rutherford builds a ribosome in Church's lab.