Question

What are the 3 main steps in eukaryotic transcription?

Answer 1

Transcription is the process of copying information in a DNA strand into a new molecule of RNA (messenger RNA). As a result a new mRNA strand is formed containing the information from the DNA strand.

The 3 main steps in eukaryotic transcription are Initiation, Elongation, and Termination.

RNA polymerase enzyme catalyzes the transcription.

Step 1 - Initiation:-

It is the beginning stage of transcription. Initiation starts when RNA polymerase enzyme binds to the promoter(start of a gene) region of the gene. This unwinds the DNA into single strands so the enzyme can read the bases in the template strand(One of the DNA strands, holds the information) in 3' - 5' direction.   

By the end of initiation, the RNA polymerase enzyme will be ready for copying the DNA strand by making a strand of mRNA with complementary base sequences.

Step 2 - Elongation:-

The addition of nucleotides to the mRNA occurs in this stage. RNA polymerase enzyme reads the template strand and builds the mRNA molecule. Pre mRNA nucleotides pairs with complementary bases in the template strand. The pre mRNA moves in the 5' - 3' direction.    

(mRNA contain uracil instead of thymine, So adenine in the template strand bin to uracil in the mRNA)

Step 3 - Termination:-

Termination is the ending step of transcription. It occurs when the RNA polymerase enzyme reaches a stop or termination sequence in the DNA strand. This signals the RNA polymerase enzyme to stop the transcription and release from the template strand.

After the detachment of the mRNA, the two separated DNA strands come back and again form the double helix.