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The 3′–5′ phosphodiester linkages inside a polynucleotide chain serve to join
A
One DNA strand with the other DNA strand
B
One nucleoside with another nucleoside
C
One nucleotide with another nucleotide
D
One nitrogenous base with pentose sugar
Detailed Solution
A nucleotide has three components: a nitrogenous base, a pentose sugar and a phosphate group.
The base is linked to the 1′ carbon of the sugar by an N-glycosidic linkage (forming a nucleoside), and the phosphate is linked to the 5′ –OH of the sugar by a phosphoester linkage.
Two nucleotides are joined when the phosphate on the 5′ carbon of one nucleotide forms a bond with the 3′ –OH of the sugar of the next; this is the 3′–5′ phosphodiester linkage, and it builds up the sugar–phosphate backbone of the chain.
The two strands of DNA are held together by hydrogen bonds between the bases, not by phosphodiester bonds.
Hence the 3′–5′ phosphodiester linkages join one nucleotide with another nucleotide.
The base is linked to the 1′ carbon of the sugar by an N-glycosidic linkage (forming a nucleoside), and the phosphate is linked to the 5′ –OH of the sugar by a phosphoester linkage.
Two nucleotides are joined when the phosphate on the 5′ carbon of one nucleotide forms a bond with the 3′ –OH of the sugar of the next; this is the 3′–5′ phosphodiester linkage, and it builds up the sugar–phosphate backbone of the chain.
The two strands of DNA are held together by hydrogen bonds between the bases, not by phosphodiester bonds.
Hence the 3′–5′ phosphodiester linkages join one nucleotide with another nucleotide.