Describe the chemical mechanism for the formation of a phosphodiester bond. What are the nucleophile, the electrophile, and the leaving group in this reaction? Why is this reaction energetically favorable, and why is the reaction effectively irreversible? Would you argue that one enzyme can catalyze both phosphodiester breakdown and synthesis, or does each process require a separate enzyme? Can you explain how this reaction is driven forward by both coupling and Q and is thus essentially irreversible?

• Phosphodiester Bonds link successive nucleotides in Nucleic acids
• The successive nucleotides of both DNA and RNA are covalently linked throgh phosphate group -"bridges",
• In which 5-phosphate group of one nucleotides unit is joined to 3- hydroxyl group of next nucleotides, creating a phosphodiester linkage.

Step-by-step explanation

Phosphodiester bond formed between nucleotides:

• Pentode sugar
• Phosphate group

Electrophile and nucleophile 

Electrophile and nucleophile are the chemical species that donate or accept electrones to form a new chemical bond .

Any molecules, ion or atom that is in some manner  deficient in Electron can act as an electrophile.

A nucleophile is usually charged negatively or neutral with a lone couple of donable electrones. H20 is an example for this.Overall Electron rich is a nucleophile

Electrophiles are generally charged positively or are neutral species with empty orbitals attracted to centre wealthy in electrons.