We identify nucleic acid strand orientation on the basis of important chemical functional groups. these are the group attached to the 5' carbon atom of the sugar portion of a nucleotide and the group attached to the carbon atom.

We identify nucleic acid strand orientation on the basis of important chemical functional groups. These are the phosphate group attached to the 5' carbon atom of the sugar portion of a nucleotide and the hydroxyl group attached to the 3' carbon atom

Explanation:

Nucleic acids are polymers formed by a phosphate group, a sugar (ribose in RNA and deoxyribose in DNA) and a nitrogenous base. In the chain, the phosphate groups are linked to the 5'-carbon and 3'-carbon of the ribose (or deoxyribose) and the nitrogenous base is linked to the 2-carbon. Based on this structure, the nucleic acid chain orientation is identified as the 5'-end (the free phosphate group linked to 5'-carbon of the sugar) and the 3'-end (the free hydroxyl group in the sugar in 3' position).