There are a multitude of terminologies used to describe DNA
cloning. Some of the terms used include Gene cloning,
molecular cloning, and Recombinant DNA Technology (3). This technology has
been around since the 1970s, and it has become a common practice in molecular
biology labs today. All of these terms have the same meaning: the transfer of
a DNA fragment of interest from one organism to a self-replicating genetic element such
as a bacterial plasmid (5). The DNA that researchers are interested in can
then be reproduced in a foreign host cell.

DNA is composed of repeating
subunits called nucleotides.  
Nucleotides are further
composed of a phosphate
group, a sugar, and a
nitrogenous base.  Four
different bases are commonly
found in DNA: adenine (A),
guanine (G), cytosine (C),
and thymine (T).  In their
common structural
configurations, A and T form
two hydrogen bonds while C
and G form three hydrogen
bonds.  Because of the
specificity of base pairing,
the two strands of DNA are
said to be complementary (6).

(6)

EcoRI is one of the many restriction
enzymes that can be obtained
from the bacteria Escherichia coli.
The function of this enzyme is
to surround the DNA molecule
at a specific base site (GAATTC)
located at two sites of one
strand and cut the strand of
the double helix. The separated
pieces have single stranded
 "sticky-ends" that allow
complementary pieces to combine
(6).  

    (6)

Process by which a plasmid is           (6)
used to import recombinant
DNA into a host cell for
cloning.