Nucleic acids and proteins are the two biologically important compounds containing both oxygen and nitrogen. Nucleic acids include DNA(Deoxyribonucleic acid) and RNA(Ribonucleic acid). DNA comprises of three chemical components – phosphate, deoxyribose(sugar) and four nitrogenous bases namely – adenine, cytosine, thymine and guanine. These contain oxygen and nitrogen atoms. Oxygen is found in the pentose sugar (Deoxyribose in DNA and ribose in RNA), Nitrogen is found in the nitrogenous bases (pyrimidine and purines)
Proteins, the building material of living cells contain carbon, hydrogen, oxygen, nitrogen and often sulphur and phosphorus. They are characterized as extremely long-chain polyamides which contain nitrogen constituting for about 16% of the protein atomic content.