Gene regulation is important in all organisms. Both prokaryotic and eukaryotic organisms constantly turn on and off their genes in response to internal and external environmental conditions.

Early gene regulation conserves more energy compared to regulation in later stages. For example, selective blocking of transcription is much more energy efficient than waiting for the transcription and translation process to finish before finally degrading or inhibiting the protein. In prokaryotic organisms, gene expression is generally regulated during the transcription stage using operons. An operon is a cluster of genes with a single promoter that can be regulated by positive and negative controls.

Eukaryotic gene regulation

Most eukaryotic organisms are multicellular and are comprised of a variety of cells with different functions, regardless of having the same genome. To create different cell types, eukaryotic organisms rely on gene regulation. Gene regulation is important for maintaining the proper specialized functions of each cell. In eukaryotic organisms, gene regulation can occur at different stages:

A digram showing a eukaryotic cell and different processes that result in gene regulation. Inside the cell, a double stranded DNA helix can be seen. The first from of gene regulation shows chromatin, which is represented by small spherical structures lining up along a strand. Chromatin can interact with DNA and regulate gene expression before transcription takes place. The second form of gene regulation occurs during RNA processing. mRNA, which are represented as short, single stranded fragments, leave the DNA helix and travel out of the nucleus. The mRNA can be degraded after leaving the nucleus, shown as a shapeless blob, which results in gene regulation after transcription and before translation. Gene regulation can occur during and after translation as well, the resulting protein strands can be degraded after translation or released as functional protein strands.

Figure 2. Different steps of gene regulation in an eukaryotic cell. In eukaryotic cells, gene regulation can occur at different stages: (A, B) Before transcription via chromatin modifications, (C) during transcription through RNA processing, (D) after transcription by mRNA degradation, and (E, F) during and after translation.