Gene ⇒ Polypeptide

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•  The amino acid sequence of polypeptides is coded for by genes

A gene is a sequence of DNA which encodes a polypeptide sequence

A gene sequence is converted into a polypeptide sequence via two processes:

  • Transcription – making an mRNA transcript based on a DNA template (occurs within the nucleus)
  • Translation – using the instructions of the mRNA transcript to link amino acids together (occurs at the ribosome)

Typically, one gene will code for one polypeptide – however there are exceptions to this rule:

  • Genes may be alternatively spliced to generate multiple polypeptide variants
  • Genes encoding tRNA sequences are transcribed but never translated
  • Genes may be mutated (their base sequence is changed) and consequently produce an alternative polypeptide sequence

The ‘One Gene – One Polypeptide’ Rule

one gene - one polypeptide