Nucleic acids are crucial biomolecules found in all living organisms. Because nucleotides have a repeating structure, they are also known as polynucleotides. A phosphate group, sugar, and nitrogenous bases make up nucleic acid. 

Nucleic acid types include:

RNA: The structure of RNA (ribonucleic acid) is a single-stranded helix.

DNA: The double-stranded helix structure of DNA (deoxyribonucleic acid).