Gene Expression

Gene expression refers to the synthesis of a product based on the nucleotide sequence of the gene. The steps are:

• Transcription: This generates an RNA molecule - called the primary transcript which has the same base sequence as the coding strand of the DNA.


• Processing: Some but not all primary transcripts are processed to generate a mature RNA molecule.


• Translation: Mature mRNA molecules are translated which generates an amino acid sequence from the RNA base sequence as per the genetic code. Other mature RNA molecules are not translated but are themselves the final gene product.

Something covered in Introductory Biology that is essential to remember for Genetics is a key difference between Prokaryotes and Eukaryotes that is illustrated below. This difference affects which processes can occur in each organism. For example, regulation based on a co-ordination of transcription and translation is limited to Prokaryotes while regulation based on RNA transport is limited to Eukaryotes.