Question

Describe the events of transcription initiation.

Short answer

Transcription initiation involves: 1) the formulation of the pre-initiation complex with transcription factors and RNA polymerase binding to the promoter, 2) unwinding of the DNA by RNA polymerase, 3) reading of the template strand by RNA polymerase and matching of complementary RNA nucleotides, 4) synthesis of RNA in the 5' to 3' direction, and 5) release of the transcription factors, RNA polymerase, and newly formed RNA upon reaching the stop signal.

Step-by-step solution

Formulation of the Pre-Initiation Complex

During this step, several transcription factors bind to a specific DNA sequence known as the promoter. These transcription factors will attract an enzyme called RNA polymerase.

Unwinding of DNA

The RNA polymerase unwinds the DNA helix near the transcription start site. This action exposes a section of the DNA strand for transcription.

Template Reading

RNA polymerase reads the template strand of DNA in the 3' to 5' direction. As it moves along the DNA, it matches complementary RNA nucleotides to the DNA sequence.

RNA Synthesis

The RNA polymerase synthesizes the RNA sequence in the 5' to 3' direction. It will continue to do this until it reaches a stop signal in the DNA sequence.

Release of Transcription Factors and RNA Polymerase

Once the RNA polymerase meets a stop signal on the DNA sequence, the transcription factors and RNA polymerase will detached, letting the newly formed RNA molecule to peel away.