Bio1100 Chapter 12 How Genes Work
  1. Gene expression in eukaryotic cells involves two steps: information encoded in DNA   is converted (expressed) into protein   via messenger RNA   .

     
  2. Transcription takes place in the nucleus  .
     
    • RNA polymerase   assembles a primary RNA transcript.



       
    • The primary RNA transcript is spliced   to form mature messenger   RNA (mRNA) which exits the nucleus.

       
    • Sequences of 3 nucleotides serve as codons   to translate the mRNA into sequences of amino   acids, using a genetic code  .


     
  3. Translation takes place in the cytoplasm  , on ribosomes.

     
    • Molecules called transfer   RNA (tRNA) bind to specific amino acids.

       
    • The ribosome reads the mRNA   and uses tRNA   molecules to build a polypeptide chain,


     
  4. Summary of the central dogma: the code must be "read" in the correct reading frame   for the message to be interpreted correctly.