protein synthesis

• Formation of polypeptide by translation of mRNA

  1. Ribosome attaches to mRNA

  2. Ribosomes move to start codon

  3. tRNA carries specific amino acid

  4. Anticodon on tRNA is complementary to codon

  5. Ribosome moves to next codon

  6. Anticodon binds to codon on mRNA

  7. Amino acids joined together by condensation forming peptide bonds with use of ATP
• Transcription of mRNA in eukaryotes

  Enzyme helicase breaks H bonds

  1. One DNA strand acts as template

  2. RNA nucleotides align by complementary base pairing

  3. Uracil pairs with Adenine

  4. RNA polymerase joins nucleotides by phosphodiester bonds

  5. Pre mRNA is spliced
• mRNA

  • single strand
  • made in transcription
  • carries genetic code to ribosome
  • translated into polypeptide
  • single gene long
  • bases in triplet
• tRNA

  • single strand folded into clover shape
  • hydrogen bonds between complimentary bases
  • C+G, U+A
  • carries amino acid to ribosome
  • 3 free bases
• Why do some organisms have a different % of bases?

  Different genes so different base sequences