DNA contains genes that code for proteins. During transcription, the enzyme RNA polymerase uses DNA as a template to create messenger RNA (mRNA). RNA polymerase breaks the bonds between DNA and transcribes the DNA code into mRNA by pairing complementary nucleotides. The mRNA then detaches from DNA and exits the nucleus, where it attaches to a ribosome. At the ribosome, translation occurs to build the protein based on the mRNA code.