The four chemical components that hold the double-stranded DNA molecule together are called nucleotides.

Each nucleotide is composed of:

* A sugar molecule (deoxyribose)

* A phosphate group

* One of four nitrogenous bases:

* Adenine (A)

* Guanine (G)

* Cytosine (C)

* Thymine (T)

These bases pair up specifically: Adenine (A) always pairs with Thymine (T), and Guanine (G) always pairs with Cytosine (C). This pairing, along with the hydrogen bonds between the bases, holds the two strands of DNA together in a double helix structure.