Non-Coding DNA (AQA A Level Biology): Revision Note
Exam code: 7402
Introns & exons
The genome within eukaryotic cells contains many non-coding sections of DNA
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. These sit in between coding regions called exons
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

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