27. Gene Regulation

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Eukaryotic gene expression

Gene structure eukaryote 2 annotated

The Central Dogma in Eukaryotes. Genomic DNA of genes often contain introns that are spliced out when an RNA matures to a mRNA. This excision of introns can result in splice variants of the same gene with variants of the same protein. Credit: Thomas Shafee (CC-BY 4.0)

Unlike prokaryotic genes, expression of genes in eukaryotic cells have complex systems of transcription factors that act on promoters to recruit RNA polymerases. Additionally, enhancer elements may reside many kilobase upstream of the promoter. These enhancers strengthen the transcription of the gene. In this case, transcription activator proteins or trans-activators augment the promoter activity.

Enhancer Nucleotide Sequence

1. DNA     2. Enhancer     3. Promoter    4. Gene     5. Transcription Activator Protein     6. Mediator Protein 7. RNA Polymerase Credit: Jon Cheff (CC-BY-SA 4.0)

Mediator proteins (coactivators) form a multiprotein complex with the activators to recruit RNA polymerase to the promoter.

 

 

Decisions… decisions…

What kinds of decisions are made for stem cells to differentiate into different cell types? What types of regulation occur during this process?

Differentiating neurons

A cluster of neuronal progenitor cells (neurosphere) dissociates and differentiates into neurons.

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