During transcription, what happens to the RNA polymerase if a repressor protein attaches to the operator?

Question

Biology is very difficult please explain.

Answer 1

Sheyanne,

 

I shall explain in some detail:

 

A transcription factor can work as a transcription activator as well as a transcription repressor. Same transcription factor can work as repressor for a group of genes and activator for another group. Such function has temporal and/or spatial specificity. A number of oncogenes are transcriptional activators during early development but repressor during adulthood, their aberrant expression leads to cell-proliferation and tumor formation/oncogenesis.

 

Transcription factors have a specific binding sites on promoter DNA, nevertheless, they can also bind to cryptic sites. Sometimes such binding is inefficient and prevents RNA polymerase to read through the signals and transcribe the downstream DNA sequence from transcribing into mRNA.

 

Operator is the part of prokaryote genes that follow different regulation than eukaryote gene expression.

 

A defined repressor bound to promoter/operator  is a signal to RNA polymerase that transcription is not required at that point or in that particular tissue. An interesting example is Progerin, the molecule that increases as we age. Higher concentration of Progerin in aged people leads to cryptic transcription and onset of many age-related conditions such as atherosclerosis. Early expression of Progerin leads to devastating childhood disease Progeria. One underlying reason of Progeria is that repressor does not inhibit transcription of Progerin mRNA.

 

Hope this helps and is clear. If not please post again and I shall explain.

 

Thank you,

 

 

 

 

Answer 2

Hi, Sheyanne!

 

The operator is the portion of DNA, at the beginning of a gene, where a transcription factor or repressor binds. If the transcription factor cannot bind, the RNA Pol cannot attach to begin transcription.

 

I hope this helps!

 

Regina G.