Here's a breakdown:

* DNA is a double helix made up of two strands.

* Each strand is a polymer made of repeating units called nucleotides.

* Each nucleotide has three parts:

* A sugar molecule (deoxyribose in DNA)

* A phosphate group

* A nitrogenous base

* The sugar and phosphate groups form the backbone of each strand.

* The bases are attached to the 1' carbon of the sugar molecule within each nucleotide.

The bases in DNA are adenine (A), guanine (G), cytosine (C), and thymine (T). They pair up in a specific way: A with T, and G with C. These pairs form hydrogen bonds between the two strands, holding the DNA helix together.