The enzyme that binds and separates DNA strands during transcription is RNA polymerase.

Here's how it works:

1. Binding: RNA polymerase binds to a specific region on the DNA called the promoter.

2. Unwinding: RNA polymerase unwinds the DNA double helix, separating the two strands.

3. Template Strand: One of the DNA strands, called the template strand, is used as a template for the synthesis of RNA.

4. RNA Synthesis: RNA polymerase reads the template strand and uses it to build a complementary RNA molecule.

Therefore, RNA polymerase plays a crucial role in both separating the DNA strands and initiating the synthesis of RNA.