Question

If helicase is not added to a reaction mixture but DNA synthesis still occurred. How is this possible?

Answer 1

• DNA synthesis is the natural or artificial creation of deoxyribonucleic acid (DNA) molecules. The term DNA synthesis can refer to DNA replication - DNA biosynthesis.
• DNA replication is the biological process of producing two identical replicas of DNA from one original DNA molecule.
• DNA synthesis (replication) is initiated by the melting of the DNA double helix. Further, local unwinding is catalyzed by the enzyme helicase, which generates regions of single-stranded DNA. The DNA is then primed by the addition of short RNA sequences that provide an initial 3′ hydroxyl group to which deoxynucleotides can be added. These primers are later removed. The extension of nucleotide primers requires a group of enzymes called DNA polymerases.
• Helicases are enzymes that bind and may even remodel nucleic acid or nucleic acid protein complexes. There are DNA and RNA helicases. DNA helicases are essential during DNA replication because they separate double-stranded DNA into single strands allowing each strand to be copied. During DNA replication, DNA helicases unwind DNA at positions called origins where synthesis will be initiated. DNA helicase continues to unwind the DNA forming a structure called the replication fork, which is named for the forked appearance of the two strands of DNA as they are unzipped apart.
• The DNA polymerases are enzymes that create DNA molecules by assembling nucleotides, the building blocks of DNA. These enzymes are essential to DNA replication and usually work in pairs to create two identical DNA strands from one original DNA molecule

If helicase is not added in the reaction mixture ,   DNA synthesis is occur when the addition of DNA poymerase. IT is responsible for replicating the strand once it unwinds and separates. Helicase is important for the DNA sunthesis (replication) for unwinding of double strand . When helicase is not added , the first step of replication (initiation) is not completed .