How does the structure of a nucleotide contribute to the structure of DNA, and its function as a carrier of genetic information?

There are four DNA nucleotides: Adenine, Cytosine, Thymine and Guanine. They are each made up of a nitrogenous base, deoxyribose sugar, and a phosphate group, and the four nucleotides differ in the structures of their bases. Two nucleotides can undergo a condensation reaction, between a deoxyrobise and a phosphate group, to form a phosphodiester bond.This aspect of their structure means they can form long polynucleotide chains, necessary for the massive amounts of genetic information held by DNA in a chromosome.  

Two nucleotides, in different DNA strands, can also undergo complementary base pairing, bound by hydrogen bonds - Adenine will only bond with Thymine, and Guanine will only bond with Cytosine. A and T form 2 hydrogen bonds with each other, and G and C form 3. This specificity ensures that during DNA replication and transcription, an exact copy of the DNA is made: free nucleotides will only bind to their complementary nucleotides. The presence of four nucleotides also means there are enough possible codons for the triplet code to code for each of the 20 amino acids during translation.