Biology Reference
In-Depth Information
67
has a length of 100 minutes, i.e. the time required to transfer the entire
chromosome under ideal conditions (Fig. 3-1). Position 0 minute designates
the location of the genetic marker
thr.
Figure 3-1.
Preliminary
E. coli
genetic map.
TRANSDUCTION
As more and more genetic markers were placed on this map, it became
obvious that the relative locations of nearby markers might not be precise,
since interrupted mating could only be accurate to a distance corresponding
to a few minutes. Another method of transferring genetic material from a
donor to a recipient
E. coli
by a bacterial virus or phage was discovered,
known as transduction (Lederberg
et al
., 1951; Zinder and Lederberg,
1952). In the case of
E. coli
(Lennox, 1955), a mutant of the wild-type P1-
phage was developed to carry a fixed amount of genetic material from any
location of the donor chromosome.
