what are the bonds between nucleotides called
DNA and RNA are composed of nucleotides that are linked to one another in a chain by chemical bonds, called ester bonds, between the sugar base of one nucleotide and the phosphate group of the adjacent nucleotide. The sugar is the 3' end, and the phosphate is the 5' end of each nucleiotide.
A polynucleotide is a nucleic acid molecule consisting of a long chain of nucleotides. Nucleotides in a polynucleotide molecule are held together by a bond between the phosphate group of one nucleotide and the sugar of a second nucleotide, which is called a phosphodiester bond.