Question

Stages of transcription Match each event with the appropriate stage of transcription.The transcription bubble created by RNA polymerase moves along the DNA template.Once bound to the promoter, RNA polymerase begins to unwind the DNA The RNA-DNA hybrid within the transcription bubble dissociates. Reaching a terminator sequence causes formation of phosphodiester bonds to stop. The RNA polymerase holoenzyme is formed.RNA polymerase releases the DNA template. The RNA polymerase holoenzyme binds to the promoter. New nucleotides are added to the 3' end of the growing RNA transcript. RNA polymerase leaves the promoter. A process called clearance or escape.

Answer 1

Transcription is a process by which RNA is synthesised from DNA. It is carried out by the enzyme RNA polymerase.

The process is carried out in three steps – Initiation, Elongation and termination.

Transcription is carried out in the following steps.

One or more sigma factor protein binds to the RNA polymerase forming a holoenzyme, allowing it to bind to promoter DNA.

After the first bond is formed in the new RNA molecule, the bonds between the RNA polymerase holoenzyme and promoter are broken

RNA polymerase creates a transcription bubble, which separates the two strands of the DNA helix. This is done by breaking the hydrogen bonds between complementary DNA nucleotides.

RNA polymerase adds matching RNA nucleotides to the complementary nucleotides of one DNA strand at the 3’ OH .

RNA sugar-phosphate backbone forms with assistance from RNA polymerase to form an RNA strand.

Hydrogen bonds of the untwisted RNA-DNA helix break, freeing the newly synthesized RNA strand.

The transcription bubble created by RNA polymerase moves along the DNA template. – Elongation

Once bound to the promoter, begins to unwind the DNA – Initiation.

The RNA-DNA hybrid within the transcription bubble dissociates – Termination.

Reaching a terminator sequence causes formation of phosphodiester bonds to stop. – Termination

The RNA polymerase holoenzyme is formed. – Initiation

RNA polymerase releases the DNA template – Termination.

RNA polymerase holoenzyme binds to the promoter – Initiation.

New nucleotides are added to the 3’ end of the growing RNA transcript – Elongation

RNA polymerase leaves the promoter. – Elongation

A process called clearance or escape – Elongation