Base pairing in DNA.

The pairs of nitrogenous bases in a DNA double helix are held together by hydrogen bonds.

The geometry of the bases are the basis of base-pairing rules.


  • Adenine (A) pairs with Thymine (T) by forming two bonds,
  • Cytosine (C) pairs with Guanine (G) by forming three bonds.

    When DNA base-pairs with RNA, A pairs with U.

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