Here's a breakdown of the three parts:

1. Nitrogenous base: This is the part that varies between the different types of nucleotides, giving them their unique identity. There are five main nitrogenous bases: adenine (A), guanine (G), cytosine (C), thymine (T), and uracil (U).

2. Pentose sugar: This is a five-carbon sugar molecule. In DNA, the sugar is deoxyribose, while in RNA, the sugar is ribose.

3. Phosphate group: This is a negatively charged molecule attached to the 5' carbon of the pentose sugar.

These three parts come together to form a nucleotide. The phosphate group plays a vital role in:

* Connecting nucleotides: The phosphate group of one nucleotide forms a bond with the sugar of the next nucleotide, creating the backbone of DNA and RNA.

* Energy storage: Phosphate groups store a significant amount of chemical energy. This energy is used in various cellular processes, such as DNA replication and protein synthesis.

Let me know if you have any other questions!