Nucleotides are the building blocks of nucleic acids like DNA and RNA. They consist of three main components:

1. A nitrogenous base: This is a ring-shaped molecule containing nitrogen. There are five main types:

* Adenine (A)

* Guanine (G)

* Cytosine (C)

* Thymine (T) (found in DNA)

* Uracil (U) (found in RNA)

2. A five-carbon sugar: This sugar is either ribose (found in RNA) or deoxyribose (found in DNA).

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

Here's how they are put together:

* The nitrogenous base is attached to the 1' carbon of the sugar.

* The phosphate group is attached to the 5' carbon of the sugar.

The specific combination of base, sugar, and phosphate group determines the type of nucleotide. For example, a nucleotide with adenine as the base, deoxyribose as the sugar, and a phosphate group is called deoxyadenosine monophosphate (dAMP).

Key points to remember:

* Nucleotides are the monomers of nucleic acids.

* They are composed of a nitrogenous base, a sugar, and a phosphate group.

* The specific type of nucleotide is determined by the combination of these three components.

I hope this helps!