<P> Cell division is essential for an organism to grow , but , when a cell divides , it must replicate the DNA in its genome so that the two daughter cells have the same genetic information as their parent . The double - stranded structure of DNA provides a simple mechanism for DNA replication . Here , the two strands are separated and then each strand 's complementary DNA sequence is recreated by an enzyme called DNA polymerase . This enzyme makes the complementary strand by finding the correct base through complementary base pairing and bonding it onto the original strand . As DNA polymerases can only extend a DNA strand in a 5 ′ to 3 ′ direction , different mechanisms are used to copy the antiparallel strands of the double helix . In this way , the base on the old strand dictates which base appears on the new strand , and the cell ends up with a perfect copy of its DNA . </P>
how to draw a complementary strand of dna
finding the correct base through complementary base pairing and bonding it onto the original strand