1st carbon of pentose sugar of nucleic acid joins

The sugars and phosphates in nucleic acids are connected to each other in an alternating chain (sugar-phosphate backbone) through phosphodiester linkages. In conventional nomenclature, the carbons to which the phosphate groups attach are the 3&;-end and the 5&;-end carbons of the sugar. This gives nucleic acids directionality, and the ends of nucleic acid molecules are referred to as 5&;-end and 3&;-end. The nucleobases are joined to the sugars an N-glycosidic linkage involving a nucleobase ring nitrogen (N-1 for pyrimidines and N-9 for purines) and the 1&; carbon of the pentose sugar ring.Ref: Harper&;s Biochemistry; 30th edition