The enzyme Helicase plays an incredibly important role in the semi conservative replication of DNA. Before replication can occur, the unwinding and separating of the two strands of the DNA double helix is carried out by helicase. Helicase travels along the DNA backbone,catalysing reactions that break the hydrogen bonds between complementary base-pairing as it reaches them. This act is known as the unzipping of the strand. This process is very important as it leads onto another stage of DNA replication.
After the two strands have split, free nucleotides that have been activated are attracted to their complementary bases. The nucleotides are lined up and they are joined together by DNA polymerase, for every codon. All the nucleotides are joined to form a complete polynucleotide chain using the DNA polymerase. As a result two identical strands of DNA are formed, each new molecule of DNA is composed of one original strand and one newly formed strand. This is called semi conservative replication. This is a vitally important process as cells divide to produce more cells needed for growth and repair of tissues. The cells need to be genetically identical to the parent cell and to each other; they need to have DNA with a base sequence identical to the original parent cell, The cells are made in the process of DNA replication; which can only be done by this enzymes. Without them the DNA double helix would never be able to be unwound and nucleotides could never be joined together after lining up.
DNA effectively carries a blueprint or instructions as to how proteins are synthesised are needed by organisms, Proteins are made up of a sequence of amino acids, which are folded into complex structures. So DNA must code for a sequence of amino acids- which makes it the genetic code.