Helicases:
Helicases are the enzymes involved in the unwinding of DNA strands. These enzymes bound to the DNA and unwind the helix; for example, dna A protein.
In addition, helicases are enzymes involved in the replication process of a linear DNA molecule. The major functions of the helicase enzyme are involved in the breakage of hydrogen bonds that are formed between the two strands of the DNA. This enables each strand to act as the template, for the synthesis of new strands.
Hence, when helicase is absent, the entire process of replication would be suppressed.