206 • Impacts of Applied Genetics— Micro-Organisms, Plants, and Animals 
Concerns raised by the implications of 
the rDNA controversy for other 
genetic manipulation 
Altering the hereditary characteristics of an 
organism by using rDNA is just one of the 
several methods of genetic engineering. The 
definition of rDNA refers specifically to the 
combination of the DNA from two organisms 
outside the cell. If the DNA is combined within 
living cells, the Guidelines do not pertain. Figure 
35 shows several methods that achieve the same 
goal— transfering genetic material from one cell 
to another, bypassing the normal se.xual 
mechanisms of mating. It is particulaiiy signifi- 
cant that DNA from different sftecies can he 
combined by all these mechanisms, only one of 
which is rDNA. Different species of bacteria, 
Figure 37.— Alternative Methods for Transferring DNA From One Cell to Another 
A. The two cells are fused in toto 
B. A microcell with a fragmented nucleus carries the DNA 
C. Free DNA can enter the recipient cell in a number of ways; by direct microinjection, through 
calcium-mediated transformation, or by being coated with a phospholipid membrane in 
order to fuse with the recipient cell 
D. The free DNA can be joined to a plasmid and transferred as recombinant DNA 
SOURCE: Office of Technology Assessment. 
