BIOINORGANIC CHEMISTRY A Short Course Second Edition

60 BIOCHEMISTRY FUNDAMENTALS

One of the in vitro (in the test tube) processes used to clone DNA is called
thepolymerase chain reaction (PCR). A vial in which PCR is to be carried out
contains all the necessary components for DNA duplication: the piece of DNA
to be cloned; large quantities of the four nucleotides, A, T, C, G; large quanti-
ties of a primer sequence, a short sequence of about 20 nucleotides synthesized
by the primase enzyme; and DNA polymerase. To conduct the process, the vial
is fi rst heated to 90 – 95 ° C for 30 seconds to separate the two DNA chains in

Figure 2.19 Production of protein via a plasmid containing a cloned cDNA fragment.
(Adapted with permission from Figure 3.8 of reference 2. Copyright 1994, University
Science Books, Sausalito, CA.)

restriction

endonuclease

plasmid plasmid with loose ends

to receive cDNA

cDNA double strand

recombinant plasmid

DNA

bacterial cell containing the recombinant DNA plasmid

bacterial DNA

the product protein

produced in large amounts

for experimentation