Structuur van een gen

In eukaryotes, the DNA is organized in the form of chromosomes inside the cell nucleus.

Each of these chromosomes contains numerous linearly arranged genes across the DNA length.

A gene is the basic unit of heredity that comprises many functional elements.

A eukaryotic gene includes the non-coding regions called introns and the coding regions called exons, which are together transcribed into a pre-mRNA.

During RNA processing, the introns are removed and the exons form the mature RNA product that is translated into a protein.

Besides introns, each gene is surrounded by many other regulatory sequences that do not encode for a protein but help regulate gene expression.

The promoter sequence is located upstream of a gene. It is here that the RNA polymerase binds and initiates transcription.

The terminator sequence present at the 3' end of the gene acts as a stop signal for RNA polymerase.

Enhancers are typically present thousands of base pairs upstream or downstream of a gene. The activator proteins bind to enhancers and upregulate gene transcription.

In contrast, silencers are bound by the repressor proteins to downregulate gene expression.