These common elements largely result from the shared ancestry of cellular life in organisms over 2 billion years ago.
[3] Key differences in gene structure between eukaryotes and prokaryotes reflect their divergent transcription and translation machinery.
This 'sense' or 'coding' strand, runs in the 5' to 3' direction where the numbers refer to the carbon atoms of the backbone's ribose sugar.
[13] Regulatory elements can overlap one another, with a section of DNA able to interact with many competing activators and repressors as well as RNA polymerase.
[15] Binding of activators and repressors to multiple regulatory sequences has a cooperative effect on transcription initiation.
The core promoter of prokaryotic genes, conversely, is sufficient for strong expression and is regulated by repressors.
[19] The 5’ UTR binds the ribosome, which translates the protein-coding region into a string of amino acids that fold to form the final protein product.
[5] This is particularly true in multicellular eukaryotes, humans for example, where gene expression varies widely among different tissues.
[11] A key feature of the structure of eukaryotic genes is that their transcripts are typically subdivided into exon and intron regions.
The most obvious difference is that prokaryotic ORFs are often grouped into a polycistronic operon under the control of a shared set of regulatory sequences.
[27] Having multiple ORFs on a single mRNA is only possible in prokaryotes because their transcription and translation take place at the same time and in the same subcellular location.
Repressor proteins bound to the operator sequence physically obstructs the RNA polymerase enzyme, preventing transcription.
These sequences switch between alternative secondary structures in the RNA depending on the concentration of key metabolites.
[31] This article was adapted from the following source under a CC BY 4.0 license (2017) (reviewer reports): Thomas Shafee; Rohan Lowe (17 January 2017).