Protein synthesis

• Transcription: (making mRNA from DNA as a template)PART1

  • RNA polymerase + protein transcription factors
  • Form transcription initiation complex
  • Attach to promoter region of DNA
  • This section of DNA unwinds, as hydrogen bonds between bases break
  • One of the strands acts as a template strand, anti-sense strand
  • RNA polymerase lines up the free RNA mononucleotides alongside the template strand and begins joining the RNA nucleotides together
• Transcription PART 2:

  • This forms mRNA
  • Once the RNA polymerase has passed, the DNA rewinds, hydrogen bonds form between bases
  • When the RNA polymerase reaches the stop codon it stops making mRNA and detaches from DNA
  • Post-transcription modification of mRNA
  • Introns are spliced out by spliceosomes
  • Remaining exons joined together in splicing process
  • mRNA moves through the nuclear pore and attaches to the ribosome in the cytoplasm
• Translation (translating mRNA base sequence into amino acid sequence) PART1:

  • The mRNA attaches to the ribosome
  • The first 1st 2 codons are now in the ribosome
  • The 1st codon, start codon, attracts the complementary tRNA molecule carrying the specific amino acid
  • The anticodons of the tRNA is complementary to the codons of the mRNA
  • The 2nd complementary tRNA molecule attaches itself to the next codon on mRNA
  • A peptide bond is formed between the two amino acids
• Translation PART 2:

  • The ribosome moves forward by one codon
  • The ribosome continues to moving along the mRNA until it reaches the stop codon
  • The polypeptide chain is then released, folding into the correct shape