Final answer:
A molecule consisting of a purine or pyrimidine base, a pentose sugar (ribose or deoxyribose), and one or more phosphate groups is called a nucleotide, the basic building block of nucleic acids.
Step-by-step explanation:
A purine or pyrimidine that is attached to a sugar (either ribose or deoxyribose) which is attached to one or more phosphate groups is called a nucleotide. Nucleotides are the basic building blocks of nucleic acids such as DNA and RNA. They consist of three components: a nitrogen-containing base (which can be a purine like adenine and guanine, or a pyrimidine like cytosine, thymine, or uracil), a pentose sugar (either ribose in RNA or deoxyribose in DNA), and one or more phosphate groups.
The nitrogenous base is attached to the 1' carbon of the pentose sugar, and the phosphate group is typically attached to the 5' carbon. In the structure of nucleic acids, nucleotides are linked together by phosphodiester bonds, forming a polynucleotide chain. Depending on the sugar present, if the sugar is ribose, the nucleotide forms RNA, and if the sugar is deoxyribose, it forms DNA.