DNA is replicated in interphase
DNA copies itself before cell division so that each new cell has the full amount of DNA.
1. The enzyme DNA helicase breaks the hydrogen bonds between the two polynucleotide DNA strands. The helix unzips to form two single strands.
2. Each original single strand acts as a template for each new strand. Free-floating DNA nucleotides join to the exposed bases on each original template strand by specific base pairing.
3. The nucleotides in the new strand are joined together by the enzyme DNA polymerase. Hydrogen bonds form between the bases on the original and new strand.
4. Each new DNA molecule contains one strand from the original DNA molecule and one new strand.
This type of copying is called semi-conservative replication because half of the new strands of DNA are from the original piece of DNA.
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