Question

How would RNA polymerase be affected if the repressor protein were not bound to the proper site on a gene?

Answer 1

RNA polymerase is an enzyme that helps in the transcription of RNA from DNA. The process of transcription does not require any primer and the repressor protein helps to stop the process of transcription and translation.

Complete answer:
Transcription is the process of formation of RNA from the template of DNA, which takes place with the help of an enzyme RNA polymerase. The RNA polymerase enzyme helps to unwind the DNA helix which forms the RNA strand from the one strand of DNA. In the case of gene expression, the repressor protein gets attached to the operator site which prevents RNA polymerase from getting attached with DNA. The operator site is present between the promoter and gene, from which the promoter helps in the attachment of RNA polymerase at the specific site of DNA. If the repressor protein does not get bound to the specific site of the gene then the process of transcription does not stop and it will continue till the repressor binds with the specific operator.

Additional information:
The repressor is of two types, aporepressor, and corepressor. Aporepressor is a proteinaceous substance that gets produced by the gene. The aporepressor does not block the operator gene alone because of the absence of a binding head. The Aporepressor works along with the corepressor which is the product of operon. The corepressor with aporepressor produces the repressor which blocks the activity of the operator gene.

Note:
In the case of the tryptophan operon, the amino acid tryptophan acts as a corepressor. In lac operon lactose acts as a repressor whereas in met operon methionine acts as a repressor. In the case of the reversible operon, the operon gets attached to the anabolic pathway which causes the availability of existing metabolites.