Here's a breakdown:

* DNA is made up of four types of nucleotides: adenine (A), guanine (G), cytosine (C), and thymine (T).

* RNA also uses adenine, guanine, and cytosine, but instead of thymine, it uses uracil (U).

Each nucleotide consists of three parts:

1. A sugar molecule: This is either deoxyribose in DNA or ribose in RNA.

2. A phosphate group: This is a molecule containing phosphorus and oxygen.

3. A nitrogenous base: This is one of the four bases mentioned above (A, G, C, T, or U).

These nucleotides link together in a chain to form the long strands of DNA and RNA. The sequence of these nucleotides determines the genetic information encoded in these molecules.