Only One DNA Strand Participates in Transcription, Why?

Transcription is considered as the first step in gene expression. It refers to the copying of DNA sequence into an RNA sequence. However, unlike DNA replication, only one strand is transcribed. The question is why both the DNA strands are not copied during transcription.

The DNA strand involved in transcription is called template DNA and the other strand which does not take part in transcription is called coding strand. Now, let's imagine, if both strands participate in transcription i.e., act as a template, they would code for RNA molecule with different sequences. Now, if these RNA strands code for proteins, they would be of different types. This means, one DNA strand would code for different proteins and this would result in complication in terms of the genetic information transfer machinery. Besides, if two RNA molecules are produced simultaneously, they would complement each other and would form a double stranded RNA. The double stranded RNA would eventually resist from being translated into proteins.