Answer:
Helicases
(1) binds at the replication fork
(4) breaks H-bond between bases
Topoisomerase
(3) binds ahead of the replication fork
(6) breaks covalent backbond in DNA backbone
Single-strand binding
(2) binds after the repication fork
(5) prevent H-bond between bases
Explanation:
Helicases can be described as a class of proteins that separate the two strands of the double helix by breaking the hydrogen bonds present between them.
The DNA is coiled so that it can fit into an organism. Topoisomerases are proteins that are involved in unwinding the DNA from the site of replication.
Single-stranded proteins are proteins that prevent the reformation of hydrogen bonds in the DNA helix at the site of transcription.