Here's why:
* DNA is double-stranded: DNA exists as two complementary strands, held together by hydrogen bonds.
* Transcription: During transcription, the enzyme RNA polymerase uses one of the DNA strands as a template to create a complementary mRNA molecule.
* Directionality: The template strand is read in the 3' to 5' direction, while the mRNA molecule is synthesized in the 5' to 3' direction.
Important Note: The other DNA strand, known as the coding strand, has the same sequence as the mRNA, except that uracil (U) replaces thymine (T) in mRNA. However, the coding strand is not directly involved in the transcription process.
