This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: DNA Replication , Subject name: Biochemistry
Enzyme that is responsible for unwinding of DNA is? 
Select and explain. 
A. Ligase, B. DNA primase, C. Helicase, D. DNA polymerase
C: Helicase
Answer: C: Helicase 
Explanation: ANSWER: (C) HelicaseREF: Lippincott's biochemistry 3rd Ed page: 400PROTEINS INVOLVED IN REPLICATION:PROTEINFUNCTIONHelicaseCauses unwinding of DNA using ATPSSB (Single strand binding protein)Keeps two strands separate , prevents renneiling of twostrandsTopisomerase I and IIThey have both nuclease (strand cutting ) and ligase activity , hence they relieve torsional strain that results from helicase induced unwindingDNA primaseInitiates synthesis of RNA primerDNA polymeraseDeoxyribonucleotide polymerisationDNA ligase /nick sealing enzymeSeals the single stranded nick between nascent chains and okazaki fragments