If the nitrogenous base forming the nucleotide is pyrimidine, it is called pyrimidine nucleotide. It is of three types. Thymidine nucleotide, cytidine nucleotide and uridine nucleotide. Pentose sugars and thymine combine to form thymidine nucleotides, pentose sugars and cytosine combine to form cytidine nucleotides, and pentose sugars and uracil combine to form uridine nucleotides.