The process of DNA transcription is when a segment of DNA is copied into messenger RNA (mRNA) by the enzyme RNA polymerase. During transcription, the DNA strands unwind, and complementary RNA nucleotides are assembled, forming a single-stranded mRNA molecule. This mRNA carries the genetic information from the DNA in the nucleus to the ribosomes in the cytoplasm, where it serves as a template for protein synthesis. Transcription is a critical step in gene expression and regulation.