Question

Order the steps from arrival of transcription-promoting factors at the eukaryotic DNA gene promoter to synthesis of an mRNA copy of the gene. Include the terms RNA polymerase II, elongation, promoter, TATA box, nucleotides, and transcription factor.

Answer 1

Answer:

Explanation:

There are 3 different types of DNA dependent RNA polymerase. RNAP II is the main enzyme synthesizing mRNAs.

1. Signals for initiation of transcription

Promoters: there are certain specific areas on the DNA that act as starting signals for initiation process.

The DNA polymerase attaches to the promoter site on the template DNA strand.

TATA Box: upstream of the transcription start site is 5'-TATAAA-3' it is referred to as the TATA Box. It acts as a signal for the start region.

2. Initiation of Transcription. The DNA helix unwind, and the RNAP binds to the promoter site on the 5' end DNA with the help of sigma factor. RNAP reaches the appropriate site of the gene and add the first nucleotide of the mRNA.

3. Elongation of Transcription: the RNAP moves along the DNA template, new nucleotides are incorporated in the nascent mRNA, one by one, according to the base pairing rule.

4. Termination of transcription: specific signals are recognized by the termination protein (Rho factor). When it attaches to the DNA, rnap can't move further. So the enzyme dissociate from DNA and consequently newly formed RNA is released.