transcription

• transcription is the first step in the synthesis of proteins
• transcription creates an mRNA copy of a gene from the DNA template.
• where does transcription take place in eukaryotic cells?


  Nucleus
• 1. RNA polymerase binds to DNA
  2. this breaks the hydrogen bonds between DNA bases, causing the strands to seperate.
  3. one strand acts as a template
  4. free RNA nucleotides align with the template strand through complementary base pairing
  5. RNA polymerase catalyse the formation of phosphodiester bonds between adjacent RNA nucleotides, forming a mRNA strand
  6. RNA polymerase reaches a stop codon and detaches from DNA
  7. mRNA is released and detaches from DNA, DNA rewinds into a double helix structure
• in eukaryotic cells transcription produces pre-mRNA which requires splicing to remove introns before it goes to the cytoplasm.
• in prokaryotic cells mRNA is produced from transcription without splicing