Non-Coding DNA (AQA A Level Biology): Revision Note

Exam code: 7402

Lára Marie McIvor

Written by: Lára Marie McIvor

Reviewed by: Cara Head

Updated on

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

_Post-transcriptional modification of RNA, downloadable AS & A Level Biology revision notes
The RNA molecule produced from the transcription of a gene contains introns that must be removed before translation can occur.
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Lára Marie McIvor

Author: Lára Marie McIvor

Expertise: Biology, Psychology & Sociology Subject Lead

Lára graduated from Oxford University in Biological Sciences and has now been a science tutor working in the UK for several years. Lára has a particular interest in the area of infectious disease and epidemiology, and enjoys creating original educational materials that develop confidence and facilitate learning.

Cara Head

Reviewer: Cara Head

Expertise: Biology & Psychology Content Creator

Cara graduated from the University of Exeter in 2005 with a degree in Biological Sciences. She has fifteen years of experience teaching the Sciences at KS3 to KS5, and Psychology at A-Level. Cara has taught in a range of secondary schools across the South West of England before joining the team at SME. Cara is passionate about Biology and creating resources that bring the subject alive and deepen students' understanding

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