Non-Coding DNA (AQA A Level Biology)

• The genome within eukaryotic cells contains many non-coding sections of DNA
  • Non-coding DNA does not code for any amino acids

• Non-coding DNA can be found between genes, as non-coding multiple repeats
  • This means they contain the same base sequences repeated multiple times

• Non-coding DNA can also be found within genes, as introns
  • The coding exons can be separated by one or more introns

• During transcription, eukaryotic cells transcribe the whole gene (all introns and exons) to produce pre-mRNA molecules
• Before the pre-mRNA exits the nucleus the non-coding sections (introns) are removed and the coding sections (exons) are joined together in a process called splicing

The RNA molecule produced from the transcription of a gene contains introns that must be removed before translation can occur.