IB Biology: DNA Replication DNA replication Explain DNA replication in terms of unwinding the double helix and separation of the strands by helicase, followed by formation of the new complementary strands of DNA polymerase. The process of replication: 1. The enzyme DNA helicase causes the unwinding of the DNA double helix at the replication fork and the hydrogen bonds between the base pairs are broken (DNA molecule is “unzipped”). 2. The unzipped DNA strand exposes 2 strands of DNA bases. Complimentary nucleotides are brought to each strand and new hydrogen bonds form. The process is supported by the enzyme DNA polymerase. 3. Each newly formed DNA double helix molecules will go into creating a chromatid. Describe the importance of complementary base pairing in maintaining the DNA base sequence. A DNA sequence is recognized to be conserved as the 2 daughter molecules have an identical base sequence to each other and to the parent molecule. This is a result of the complimentary base pairings. State the DNA replication is semi-conservative. The process of DNA replication is described as semi-conservative because the daughter molecules of DNA each consists of one old parent strand and a new strand formed by the free nucleotides.