Differences in Translation between Prokaryotic and Eukaryotic Cells

Prokaryotic mRNA Translation

• Noncoding Region: Located at the 5' end; not read by ribosomes.
• Shine-Dalgarno Sequence: Site recognized and bound by the ribosome.
  • Prokaryotic ribosome binds here.
• Start Codon (AUG): Signals the start of translation.
• Stop Codon: Signals the end of translation.
• Noncoding Regions: Present before and after the coding sequence.

Eukaryotic mRNA Translation

• 5' Cap:
  • A guanine nucleotide with a methyl group.
  • Serves as the ribosomal binding site.
• Noncoding Region: Follows the 5' cap; not translated.
• Start Codon (AUG): Signals the start of translation.
• Stop Codon: Signals the end of translation.
• Poly-A Tail:
  • Composed of adenine nucleotides.
  • Length is 100-250 nucleotides.
  • Prevents degradation by enzymes.

Protection from Degradation

• Prokaryotic mRNA: No special features.
  • Transcription and translation occur simultaneously in the cytosol.
• Eukaryotic mRNA:
  • Transcription occurs in the nucleus; translation occurs in the cytoplasm.
  • 5' cap and poly-A tail protect against enzyme degradation during transit.

First Amino Acid in Polypeptide Chain

• Prokaryotic Cells: Formylmethionine as the first amino acid.
  • Formyl group is attached to methionine.
  • Acts as an alarm system in the human body, triggering immune response.
• Eukaryotic Cells: Methionine as the first amino acid.