* Adenine (A)

* Guanine (G)

* Cytosine (C)

* Thymine (T)

These nucleotides are paired together in DNA: Adenine pairs with Thymine (A-T) and Guanine pairs with Cytosine (G-C).

In RNA, Thymine is replaced by Uracil (U). So the four nucleotides in RNA are:

* Adenine (A)

* Guanine (G)

* Cytosine (C)

* Uracil (U)

These nucleotides are also paired together in RNA: Adenine pairs with Uracil (A-U) and Guanine pairs with Cytosine (G-C).