Here's why:
* DNA as the blueprint: DNA contains the genetic code that determines the sequence of amino acids in proteins. This code is organized into genes.
* Transcription: The first step in protein synthesis is transcription. During transcription, a copy of the gene's DNA sequence is made in the form of messenger RNA (mRNA). This copy is made by an enzyme called RNA polymerase.
* Template strand: The DNA strand that acts as the template for mRNA synthesis is called the template strand (also known as the non-coding strand). This strand is the one that is read by RNA polymerase, and its sequence is complementary to the mRNA sequence.
* Unraveling: For RNA polymerase to access the DNA sequence, the double helix must temporarily unwind, exposing the template strand. This "unraveling" happens locally at the gene being transcribed.
In summary: The template strand of DNA unravels during transcription to allow RNA polymerase to read the genetic code and create a copy in the form of mRNA. This mRNA molecule then travels out of the nucleus and serves as the blueprint for protein synthesis (translation).
