12 
The developments in molecular genetics during the past 10 years, but 
particularly in the last 3 or 4, have brought us nearer to that day of 
reckoning. For now, and in the next few years, we are going to be doing 
things that were thought to be completely improbable just a few years ago. 
Genes from virtually any living organism can be put into another, com- 
pletely unrelated organism. For example, the genes from one species of 
bacteria can be transferred to a completely unrelated species of bacteria. 
Even more remarkable, the genes from a toad ( Xenopus laevis ) or a fruit 
fly ( Drosophila melanogaster ) have been introduced into the bacterium 
Escherichia coli , which I will refer to as _E. coli . 
Now, because the recipient bacterium continues to multiply, it pro- 
pogates these newly acquired genes as part of its own chromosomal comple- 
ment. I believe it is very likely that any kind of gene from any kind of 
organism — elephant, man, or whatever — could be introduced into li. coli 
and eventually into other organisms. 
This ability to join together genetic material from any two sources 
and to propogate these hybrid elements in bacterial and animal cells has, 
I believe, produced a qualitative change in the field of genetics. I 
don't believe it can be argued that this is another, perhaps easier way to 
do what we have been doing for a long time. For now, for the first time, 
there is available a method which allows us to cross very large evolution- 
ary boundaries, and to move genes between organisms that have never before 
had genetic contact. Consequently, we are placed in an area of biology 
with many unknowns, and it is our ignorance of this unknown that compels 
us, I believe, to pause, reflect, and to assess the implications of this 
line of research. 
Before going on to examine the implications, I want to review briefly 
for you what this newly developed technique is all about. How are genetic 
elements from diverse organisms fused together into one chromosome and 
then introduced into cells where they can be propagated indefinitely? I 
don't propose to give you a short course in molecular biology, but let me 
at least summarize a few brief facts. 
About 25 to 30 years ago it was established that genes are made of 
DNA, therefore genetic information is synonomous with chemical structure. 
In 1953 the DNA structure was solved, and it was clear that genes are 
nothing more than segments of the DNA molecule — that is, segments arranged 
linearly along the backbone of the double helix formed by two strands of DNA. 
Normally these arrangements are conserved from one generation to the 
next. Occasionally DNA segments exchange between two different chromosomes, 
during sexual modes of reproduction. But generally this is limited to 
organisms of the same species. 
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