Nucleotide facts for kids
A nucleotide is composed of a nucleobase (nitrogenous base), a five-carbon sugar (either ribose or 2-deoxyribose), and one phosphate group. Nucleotides contain either a purine or a pyrimidine base. Ribonucleotides are nucleotides in which the sugar is ribose. Deoxyribonucleotides are nucleotides in which the sugar is deoxyribose.
In DNA, the purine bases are adenine and guanine, while the pyrimidines are thymine and cytosine. RNA uses uracil in place of thymine. Adenine always pairs with thymine by 2 hydrogen bonds, while guanine pairs with cytosine through 3 hydrogen bonds, each due to their unique structures.
Images for kids
This nucleotide contains the five-carbon sugar deoxyribose (at center), a nitrogenous base called adenine (upper right), and one phosphate group (left). The sugar joined with the base forms a nucleoside called deoxyadenosine. The whole structure is a nucleotide constituent of DNA, with the name deoxyadenosine monophosphate.
Showing the arrangement of nucleotides within the structure of nucleic acids: At lower left, a monophosphate nucleotide; its nitrogenous base represents one side of a base-pair. At upper right, four nucleotides form two base-pairs: thymine and adenine (connected by double hydrogen bonds) and guanine and cytosine (connected by triple hydrogen bonds). The individual nucleotide monomers are chain-joined at their sugar and phosphate molecules, forming two 'backbones' (a double helix) of a nucleic acid, shown at upper left.
Nucleotide Facts for Kids. Kiddle Encyclopedia.