Fosfodiesterike

Fosfodiesterike, known in English as phosphodiester bonds, are covalent linkages that connect nucleotides in nucleic acids. Each bond joins the 5' phosphate group of one nucleotide to the 3' hydroxyl group of the next, forming a sugar-phosphate backbone in DNA and RNA. This backbone provides the structural framework and directional polarity of nucleic acids: a free 5' end and a free 3' end in linear polymers; in double-stranded DNA the two strands run anti-parallel, 5' to 3' relative to each other.

Formation occurs during polymerization, catalyzed by DNA polymerase in DNA replication and RNA polymerase during transcription. The reaction is a dehydration synthesis, releasing a molecule of water as the phosphodiester bond forms.

Hydrolysis or enzymatic cleavage by nucleases can sever fosfodiesterike, yielding shorter fragments or nucleotides. The chemical stability of these bonds under physiological conditions contributes to genomic integrity, while RNA's 2'-hydroxyl group makes RNA phosphodiester bonds more prone to hydrolysis, contributing to RNA's relative instability compared to DNA.

Defects or breaks in fosfodiesterike can have severe consequences, including genetic mutations and cell death; cells possess repair pathways to mend breaks in backbones. Phosphodiester bonds are central to molecular biology, underpinning genetic information storage and the flow of genetic information.