Describe the linking of nucleotides by phosphodiester bonds

Sourav PanOctober 29, 2024

Answered

Nucleotides are linked together to form a nucleic acid strand (such as DNA or RNA) through phosphodiester bonds. Here’s how this linking occurs:

1. Formation of the Bond:
   • A phosphodiester bond forms between the phosphate group of one nucleotide and the 3′ hydroxyl (–OH) group of the sugar in the next nucleotide. This reaction is a type of condensation reaction, where a molecule of water is released as the bond forms.
2. Backbone of the DNA/RNA Strand:
   • This bond creates a continuous sugar-phosphate backbone, where the phosphate group connects the 5′ carbon of one sugar to the 3′ carbon of the next sugar in the chain. This results in a strand with a 5′ end (with a free phosphate group) and a 3′ end (with a free hydroxyl group).
3. Antiparallel Strands in DNA:
   • In double-stranded DNA, two strands run in opposite directions (antiparallel) due to the orientation of these phosphodiester bonds. One strand runs from 5′ to 3′, while the other runs from 3′ to 5′.
4. Stability of the Structure:
   • Phosphodiester bonds are covalent and provide significant stability to the DNA and RNA backbone, which is critical for preserving genetic information.

The phosphodiester linkage is fundamental for the structure of nucleic acids, providing a stable and consistent backbone that supports base pairing and allows the molecule to carry genetic information reliably.