But where were the genes?
What genes are made of remained a mystery
but some scientists thought they knew where they were.
Chromosomes - curious filaments in the nucleus of each cell
behaved a bit like genes.
You get one from each parent and pass one on to each offspring.
Chromosomes contain protein,
as well as a rather boring molecule called deoxyribonucleic acid,
DNA for short.
Most people were convinced that if chromosomes held the genes
then protein was the place to look
because noting else was complicated enough.
Fred Sanger is the only person ever to have received two Nobel Prizes
in the same subject.
He remembers just how unpromising DNA seemed.
When I started working in the 1940s,
DNA was thought to be just something that was in the nucleus
and probably a structural thing
but the composition of it was much too simple to imagine
that it had much biological activity.
