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On the transcriptional level, gene expression is regulated by altering transcription rates. Genes that encode proteins include exons which will encode the polypeptides, introns that are removed from mRNA before the translation of proteins, a transcriptional start site in which RNA polymerase binds, and a promoter.
In general gene expression is regulated through changes [44] in the number and type of interactions between molecules [45] that collectively influence transcription of DNA [46] and translation of RNA. [47] Some simple examples of where gene expression is important are: Control of insulin expression so it gives a signal for blood glucose regulation.
Eukaryotic transcription occurs within the nucleus where DNA is packaged into nucleosomes and higher order chromatin structures. The complexity of the eukaryotic genome necessitates a great variety and complexity of gene expression control. Eukaryotic transcription proceeds in three sequential stages: initiation, elongation, and termination. [1]
Any step of gene expression may be modulated, from signaling to transcription to post-translational modification of a protein. The following is a list of stages where gene expression is regulated, where the most extensively utilized point is transcription initiation, the first stage in transcription: [citation needed]
Transcription is the process of copying a segment of DNA into RNA for the purpose of gene expression. Some segments of DNA are transcribed into RNA molecules that can encode proteins, called messenger RNA (mRNA). Other segments of DNA are transcribed into RNA molecules called non-coding RNAs (ncRNAs).
Transcription factors are proteins that bind to specific DNA sequences in order to regulate the expression of a given gene. There are approximately 1,400 transcription factors in the human genome and they constitute about 6% of all human protein coding genes. [ 21 ]
Activation of transcription depends on whether or not the transcription elongation complex, itself consisting of a variety of transcription factors, can induce RNA polymerase to dissociate from the Mediator complex that connects an enhancer region to the promoter. [4] Role of transcription factors and enhancers in gene expression regulation
Post-transcriptional regulation is the control of gene expression at the RNA level. It occurs once the RNA polymerase has been attached to the gene's promoter and is synthesizing the nucleotide sequence. Therefore, as the name indicates, it occurs between the transcription phase and the translation phase of gene expression. These controls are ...