What are DNA strands held together by hydrogen bonds separated by?

Answer 1

Hydrogen bonding infers that the two strands are VERY close together so the strands are practically right next to each other. As the strands wind up in a larger scale they wrap around proteins to keep them secure and finally form a combined material called chromatin which make up chromosomes in eukaryote cells.

Answer 2

DNA strands held together by hydrogen bonds are separated by enzymes called helicases. Helicases unwind the double helix structure of DNA, allowing for other enzymes such as DNA polymerase to access the separated strands and replicate the DNA.