True statements about DNA structure

Nucleotides polymerise by forming bonds between the carbon of the sugar and an oxygen atom of the phosphate. The bases do not take pa in the polymerisation, so the chain is held together by a sugar-phosphate backbone with the bases extending off it. This means that the nucleotides can join together in any order along the chain. Many nucleotides form a polynucleotide. A polynucleotide has a free phosphate group at one end and a free OH group at the other end.