here's an example of a protn, an enzyme protein, that performs -- it breaks apart a two-part sugar molecule and there's a breakdown of the protein and that two-part sugar that looks a bit like a barbell and you see there's a perfect hand in glove fit that is responsible for the chemical breaking that the enzyme accomplishes. and this is typical of almost all proteins. they perform their function because of this exquisite three-dimensional specificity, this hand in love fit. the key question in biogy, how does that specificity arise and we now show specificity derives from the specificity of consequence in the amino acids which in turn derives from the in fact, the instructions, the digital code stored along the spine of the dna molecule. so that is what i call the dna enigma and i willxplain in a minute why i call that an enigma. before we do that, though, it might be helpful to have a nice visual representation of exactly what the instructions, the digital code in dna does within the molecule -- or within the cell. we now know that and it's nice to have a look. i'm in just a second press a

replicating organisms but self replication in turn presupposes the existence of information rich dna and protns, the information in dna in the process of self replicion. ere is a problem for scientists to say we want to rescue the origin of life, chemical evolution from the improbability by bringing in natural selection because natural selection is relevant once y have selfeplicating organisms which in turn implies that you already have dna and protein, we are trying to explain the origin of the informatn of the and a protein so illustrating this with my students, like the guy who is walking home from work, hmust be a philosopher of science or something, he fal in a big hole and can't get out but he says no problem, all i need is a ladder, he walks home and gets the ladder, walks back, jumps in and climbs out. . begginthe question of ere you get the ladder, where you get the information rich dna protein th makes of replication and natural selection possible. one of the leading origin of life biologist's says series of pre biotic natural selection have a problem, they need information which impl