Transcription by RNA polymerase

Transcription begins with recognition of a
specific site by RNA polymerase (1). Here the
double helix is opened and begins to unwind.
RNA synthesis begins (initiation, 2) and continues
with elongation (3). As the polymerase
moves along the DNA, mRNA is synthesized.
The DNA that has been transcribed rewinds into
the double helix behind the polymerase. At termination
(4), the RNA polymerase is removed
fromtheDNA. At this point, the formation of the
unstable primary transcript is completed. Since
it is unstable, it is immediately translated in
prokaryotes and modified (processed) in
eukaryotes (see p. 50). All the processes aremediated
by the complex interaction of a variety of
enzymes.