Question

Why does a double-helix DNA molecule transcribe into a single-stranded RNA molecule?

Answer 1

A double-helix DNA molecule transcribes into a single-stranded RNA molecule, as only one strand is used to code for RNA. If both strands serve as templates, they will code for two RNA molecules. If separate RNA molecules code for proteins, each protein will have a unique amino acid sequence. As a result, a single DNA sequence could encode two distinct proteins.
Simultaneous production of two complementary RNA molecules results in double-stranded RNA. Thus, RNA would not be converted into protein.