Question

Briefly describe the functions of the activator, repressor, co-repressor and inducer in the regulatory process. Additionally, describe the negative and positive transcriptional regulation with your own words.

Answer 1

Answer:-

Function of activator:- Transcriptional activator is a protein (transcription factor) which increases gene transcription or gene set. Many activators are proteins bound to DNA that bind to enhancers or elements promotor-proximal.When an activator is connected to its DNA binding site, it increases operon transcription (e.g., by helping to bind the promoter to RNA polymerase).

Function of repressor :- Throughout molecular genetics, a repressor is a protein that binds DNA or RNA, which prevents the expression of one or more genes by binding to the operator or associated silencer. A DNA-binding repressor blocks the attachment of RNA polymerase to the promoter, thereby preventing messenger RNA transcription of the genes.Repressors inhibit gene transcription in response to an external stimulus, while activators increase gene transcription in response to an external stimulus.

Function of co repressor :- A corepressor is a substance in the field of molecular biology which inhibits gene expression. A corepressor down-regulates (or represses) gene expression by binding a repressor transcription factor to and activating it.Corepressors are transcriptional regulators that can not bind individually to DNA and are recruited by DNA-binding TFs directly or indirectly to suppress target gene expression.

Function of inducer :- An inducer is a molecule in molecular biology which regulates the expression of genes. There are two ways an inducer works; namely: by removing repressors. The gene is expressed because the repressor is binded by an inducer.

● Negative and positive transcriptional regulation ;- In negative regulation a repressor protein binds to an operator to stop expressing a gene. To allow RNA polymerase to initiate transcription, a transcription factor is required in positive regulation to bind to the promoter.

Positive regulation :- For transcription to proceed, binding of specific protein (activator) is needed. By helping with the ignition, DNA bound activators can control transcription. Often they attach RNA polymerase to the promoter to do this.

Negative regulation :- Binding a particular protein (repressor) prevents the process of transcription.
DNA-binding repressors also act to prevent RNA polymerase from binding to the promoter or blocking RNA polymerase movement