5- Transcription

• Transcription


  1. DNA helicase breaks hydrogen bonds between DNA strands

  2. Complementary RNA nucleotides move into place and form hydrogen bonds with exposed DNA bases

  3. RNA polymerase joins RNA nucleotides by forming phosphodiester bonds

  4. RNA polymerase detaches from DNA when it reaches the end of the gene
• Sense strand


  The DNA strand that has the same base sequence as the mRNA, except that thymine is replaced by uracil
• Antisense/Template strand


  The DNA strand that is complementary to the mRNA
• mRNA movement


  1. mRNA moves out of the nucleus through a nuclear pore

  2. mRNA can then take part in translation in the cytoplasm
• Most mRNA molecules are hundreds of nucleotides long
• Functional RNA molecules


  • Transfer RNA
  • Ribosomal RNA