Today, it is research with human embryonic stem cells and attempts to prepare cloned stem cells for research and medical therapies that are being disavowed as being ethically unacceptable.

That work led to the emergence of the recombinant DNA technology thereby providing a major tool for analyzing mammalian gene structure and function and formed the basis for me receiving the 1980 Nobel Prize in Chemistry.

With time, many of the facts I learned were forgotten but I never lost the excitement of discovery.

Moreover, the concern of some that moving DNA among species would breach customary breeding barriers and have profound effects on natural evolutionary processes has substantially disappeared as the science revealed that such exchanges occur in nature.

Today, it is research with human embryonic stem cells and attempts to prepare cloned stem cells for research and medical therapies that are being disavowed as being ethically unacceptable.

But the prospects of designing chemical plants for industrial scale chemical processes seemed far less interesting than the chemical events that occur in biological systems.

By then, I was making the slow transition from classical biochemistry to molecular biology and becoming increasingly preoccupied with how genes act and how proteins are made.