A initiator protein unwinds a short stretch of the DNA double helix. Then a helicase attaches to and breaks apart the hydrogen bonds between the bases on the DNA strands, pulling apart the two strands.
The information in a strand of DNA is copied into a new molecule of mRNA. DNA safely stores genetic material in the nuclei of cells as a reference, or template. This happens in the nucleus.
Where ribosomes in a cell's cytoplasm create proteins. mRNA is decoded by a ribosome, outside of the nucleus, to produce a amino acid chain, or polypeptide. It happens in the ribosome.