Translation

• Translation is the second stage of protein synthesis. In both prokaryotes and eukaryotes translation occurs at the ribosomes
• Translation - The stage in which the polypeptide chain is created using both the mRNA base sequence and the tRNA
• Translation steps:

  1. Once the modified mRNA has left the nucleus it attaches to a ribosome in the cytoplasm
  2. The ribosome attaches at the start codon
• Translation steps:

  3. The tRNA molecule with the complementary anticodon to the start codon binds to the mRNA. It has a specific amino acid attached
• Translation steps:

  4. The ribosome moves along the mRNA molecule to enable another complementary tRNA to attach to the next codon on the mRNA

  5. The two amino acids that have been delivered by the tRNA molecule are joined by a peptide bond. This is catalysed by an enzyme and requires ATP
• Translation steps:

  6. The ribosome continues to move along the mRNA and tRNA's arrive with amino acids at each codon until a stop codon is reached.

  • The ribosome, mRNA and tRNA separate and the polypeptide is complete
• Translation ends:

  The ribosome continues to move along the mRNA and tRNA's arrive at each codon until a stop codon is reached

  • The stop codon does not code for an amino acid and therefore the ribosome detaches and translation ends
• After the mRNA (a complementary copy of the DNA sequence of a gene) is transcribed, it travels to a ribosome where it is translated into a polypeptide chain

  • Translation requires another form of RNA - transfer RNA (tRNA)
• Role of ribosomes:

  • Translate mRNA into amino acids and synthesise the polypeptide
• Role of tRNA:

  • Reads the mRNA codons and brings the corresponding amino acid into the ribosomes