Q78: Which type of bond is synthesized by DNA ligases? - Molecular Biology and Recombinant DNA Methods - Veterinary Biotechnology- ICAR JRF/SRF 2024 | Agrigyan

• DNA Ligase Function: DNA ligases catalyze the formation of a covalent phosphodiester bond between adjacent $3'\text{-OH}$ and $5'\text{-phosphate}$ termini of nicked double-stranded DNA.
• Biological Role: Essential for joining Okazaki fragments on the lagging strand during DNA replication, as well as sealing repaired nicks during excision repair and recombination.
• Energy Requirement: Eukaryotic and bacteriophage T4 ligases require ATP, while bacterial DNA ligases (e.g., E. coli) utilize $\text{NAD}^+$ as a cofactor.

Correct option: (2) Phosphodiester bonds between nucleotides.