In DNA there are two spiral chains of polynucleotides that are arranged helically, while RNA is a single-stranded molecule.
Polynucleotides
consist of a long, unbranched chain with a sugar backbone (ribose or deoxyribose) and phosphate units with heterocyclic bases that protrude from the chain at regular intervals. The two antiparallel chains of DNA are held together by hydrogen bonds that link the bases of each complementary nucleotide; adenine is linked to thymine by 2 hydrogen bonds and guanine to cytosine by 3 hydrogen bonds. There are two main types of polynucleotides, DNA and RNA (figure).DNA contains the genetic blueprint for life and contains the instructions necessary for the development, survival, and reproduction of an organism. RNA, on the other hand, carries out the instructions encoded in DNA when synthesizing proteins, which are crucial to the structure and function of an organism. The unique structure of polynucleotides allows the replication and transmission of genetic information from generation to generation (Watson and Crick, 1953b; Watson and Crick, 1953a).).
