Plasmid pUC18
A plasmid is a circular dsDNA molecule a few hundred or
thousand base pairs in circumference. Naturally-occuring plasmids
are viruses of bacteria. The artificial plasmid pUC18 has been
genetically engineered to include a gene for antibiotic
resistance to Ampicillin (ampR), and
a gene (and its promoter)
for the enzyme beta-galactosidase (lacZ). The lacZ gene contains a polylinker region, with a series of
unique restriction sites found nowhere else in the plasmid.
Digestion with any one of these endonucleases will make a single
cut that linearizes the circular plasmid DNA, and allow it to recombine
with foreign DNA that has been cut with the same
endonuclease.
Figures ©
2002 by Griffiths
et al.; all text material © 2011
by Steven M. Carr