Transcription in eukaryotic cells

The RNA formed by transcription must now have its introns removed to create mature mRNA only containing exons.

Eukaryotic genes can contain exons and introns. These ideas relate to what happens during transcription.

Notice that the introns are transcribed into the RNA but at the end of the transcription process the mature mRNA only contains the exons. These exons can be spliced together in different orders in a process that occurs after transcription.

Figure 7.2.1 http://upload.wikimedia.org/wikipedia/commons/1/12/DNA_exons_introns.gif

This leads to one gene being able to produce many different polypeptide chains and therefore many proteins.