Understanding:
• 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
