Within a gene, exons code for amino acid sequences; exons are separated by non-coding sequences called introns
Inside a gene, coding sections called exons carry the instructions for building a protein. Non-coding sections called introns sit between the exons and do not code for amino acids.
Real World
The human dystrophin gene — mutated in Duchenne muscular dystrophy — spans 2.4 million base pairs but contains only 79 exons; the vast intervening intronic sequences are spliced out before the mRNA is translated.
Exam Focus
Use the memory aid 'Exons are Expressed, Introns are Intervening' to avoid swapping definitions under exam pressure.
Evaluation Scaffold
A four-step framework for high-quality evaluation. Use this for 'assess', 'evaluate', and 'to what extent' questions.
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