PROTEIN SYNTHESIS

• Eukaryotic mRNA production vs Prokaryotic

  • EUKARY= both introns and exons are translated so splicing needs to occur to remove introns and join up exons.
  • Pre-MRNA is also only produced in eukaryotic
  • PROKARY= no introns so mRNA can be used for translation straight away
  • Mrna is too big so will diffuse via nuclear pores in both
• MRNA

  • Single strand
  • Made in transcription
  • Carries the genetic code to ribosomes
  • Bases in triplet codons
  • Diff lengths depending on the length of gene
• tRNA

  • Single strand folded into clover shape
  • Hydrogen bonds between bases
  • 3 free bases with anticodon at one end and a amino acid binding site at the other
  • All same size
  • Carries amino acids to ribosomes
• TRANSCRIPTION (step 1)

  1. mRNA copy of gene is made from DNA
  2. DNA helicase is attached to RNA polymerase
  3. H Bonds break causing DNA to unravel and expose bases
  4. Free RNA Nucleotides line up alongside exposed bases on DNA strand and join via RNA polymerase forming either pre-mrna or mrna molecules
  5. RNA polymerase moves along DNA to separate strands and forms a mrna strand
  6. When it reaches a stop codon it releases mRNA strand and DNA recoils
• ROLE OF ATP


  Provides energy for amino acids to join to tRNA/ formation of peptide bonds btwn amino acids