Transcription is the process where the DNA code is used as a template to create a complementary RNA strand. The conversion from DNA to RNA is performed using an enzyme called RNA polymerase. The RNA polymerase reads the DNA strand and incorporates nucleotides complementary to the DNA sequence into the growing RNA strand. As with DNA replication, guanine will still only bind to cytosine. However, the RNA polymerase will incorporate Uracil instead of Thymine when it encounters an adenine in the DNA sequence. If the RNA strand encodes a protein it is messenger RNA (mRNA). Alternatively, the RNA could encode for transfer RNA (tRNA) or ribosomal RNA (rRNA) to assist with translation.
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