130 Chapter 6The Mechanism of Transcription in Bacteria a Tr

130 Chapter 6/The Mechanism of Transcription in Bacteria (a) Trailing-edge FRET o released: decreased FRET Core +1 o not released; decreased FRET Core (b) Leading-edge FRET o released; decreased FRET Core or not released; increased FRET Core NTPs NTPs NTPs NTPs Core Core Core Core (a)

Solution

The sigma factor helps in initiation of the transcription as the initiating factor in the process. it allows the binding of RNA polymerase to gene promoters. FRET is helpful in knowing the movement of RNA polymerase with respect of DNA during the promotion and elongation step of transcription. While the elongation step appears it is very easy to know the distances between two probes using FRET.

1) trailing- edge FRET: FRET is added to know how the RNA polymerase is moving with respect to DNA during transcription. It will be helpful in knowing the measurements of positions within the RNA polymerase and between the positions in upstream DNA. the movement tracking is easy with fluorocently labelled molecule linked to the fluorocent probe at upstream of DNA.

2) Leading- edge FRET: this will be helpful in knowing the positions within the RNA polymerase and positions between the downstream DNA. here the fluorocent acceptor is incorporated in downstream DNA while the fluorocent donor is within sigma factor.