Which end does the RNA polymerase begin transcribing? (thick or thin and why?)?

Answer 1

* RNA polymerase (RNAP) recognizes and specifically binds to the promoter region on DNA. At this stage, the DNA is double-stranded ("closed"). This RNAP/wound-DNA structure is referred to as the closed complex.
* The DNA is unwound and becomes single-stranded ("open") in the vicinity of the initiation site (defined as +1). This RNAP/unwound-DNA structure is called the open complex.
* The RNA polymerase transcribes the DNA, but produces about 10 abortive (short, non-productive) transcripts which are unable to leave the RNA polymerase because the exit channel is blocked by the σ-factor.
* The σ-factor eventually dissociates from the holoenzyme, and elongation proceeds.