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In DNA, the nitrogen bases will join together via weak bonds
known as hydrogen bonds.
Each nitrogen base has a unique lock and key shape, so each
base bonds to only one other kind of base.
The base pairing rule is as follows:
Adenine to Thymine ( A--T )
Guanine to Cytosine ( G--C )
The dashed line between the A & T or G & C represent
the hydrogen bonds.
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Slichter