9 
IV. 
BACKGROUND 
A. Description of the Recombinant DNA Experimental Process* 
All living things, from subcellular particles to higher organisms, 
contain the specific information needed for their reproduction and 
functions. The basic source of this information is deoxyribonucleic 
acid (DNA), which is the principal substance of the genes, the units 
of heredity. Each gene directs the synthesis of a different protein, 
and the diversity in structure and function of proteins accounts for the 
differences between all living things. 
Each cell of an organism is composed of various organized struc- 
tures, several of which contain DNA. Figure IV- 1 illustrates a typical 
eukaryotic (i.e., nucleated) cell. Bacterial cells are much less complex, 
showing fewer organelles and no organized nucleus. 
Figure IV-1 
* The reader is referred to references 1, 2, 3, 4, and 5 at the end 
of Section IV for additional information on the scientific concepts 
introduced in this section. References 3 and 5 should be especially 
informative to nonscientists. 
