How is DNA replicated?

DNA replication is a multi stage process which is carried out in the nucleus of the cell. We know that DNA is in a double helix structure and for replication to occur it must be unwound into two single strands. This is carried out by an enzyme. The enzyme breaks the hydrogen bonds formed between the base pairs. The DNA is now in two separate strands and both are used as template strands for DNA replication. New strands are synthesised against the template strands using complementary base pairing.The base pairs in DNA are A - T and C - G (Adenine, Thymine, Guanine and Cytosine) DNA replication occurs in a 5' (5 prime) to 3' (3 prime) direction ONLY. The synthesis is aided by the enzyme DNA polymerase. The hydrogen bonds are reformed between the bases and a new complementary strand of DNA is synthesised. The new strand contains 1 original strand of DNA and 1 newly synthesised.