DNA

1
DNA

• Transcription

2
Transcription

• Process by which genetic information from a
  strand of DNA is copied into a strand of mRNA
• Occurs in the nucleus in eukaryotic cells

3
Steps in Transcription

• A protein known as RNA polymerase binds to a
  strand of DNA and unzips it
• RNA polymerase brings in the complementary
  nitrogen bases to match up with the template
  strand of DNA
• The sugar-phosphate backbone of the mRNA is
  formed
• The mRNA is released and the DNA re-zips

4
mRNA Splicing

• In eukaryotic cells, the mRNA is not yet ready to
  be released into the cytoplasm
• Eukaryotic cells contain introns, pieces of RNA
  that do NOT code for proteins, and exons, pieces
  of RNA that do code for proteins

5
mRNA Splicing (cont.)

• The RNA must be cut apart so that the introns can
  be removed
• The remaining exons are joined or spliced
  together to form the mRNA strand that can now be
  released into the cytoplasm