DNA is copied into RNA by the enzyme, RNA polymerase
During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand. The genome of a given organism contains thousands of genes, but not all these genes need to be active at any given moment.
A gene is "expressed" when it has been transcribed into mRNA (and translated into protein), and there exist many cellular methods of controlling the expression of genes such that proteins are produced only when needed by the cell.
Transcription is the first step of gene expression, in which a particular segment of DNA is copied into RNA by the enzyme, RNA polymerase. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes. Transcription factors are regulatory proteins that bind to the start of genes, either promoting or inhibiting the transcription of the gene
During transcription, a DNA sequence is read by an RNA polymerase, which produces a complementary, antiparallel RNA strand. As opposed to DNA replication, transcription results in an RNA complement that includes uracil (U) in all instances where thymine (T) would have occurred in a DNA complement. Also unlike DNA replication where DNA is synthesized, transcription does not involve an RNA primer to initiate RNA synthesis.