Although this question should probably be ruled off-topic as unresearched homework, I fancy that not all readers will be familiar with the VPg primer for viral RNA replication. I shall therefore suggest some of the chemical aspects of this process that might be include in a presentation, and comment on the process itself.
Some Chemical features of VPg-primed viral RNA replication
The chemical reaction. This is no different from many other reactions involving an RNA polymerase. It involves the reaction of an NTP with the 3’OH of the ribose on a growing RNA chain, forming a phosphodiester bond, thus extending the chain. The growing RNA chain is termed a primer because it is required to start the addition in many cases, however in the case of many single-stranded RNA viruses the actual initiation of a new strand uses a primer composed of a small peptide to which to U residues have been attached. Simple diagrams of this process are generally presented for DNA-dependant DNA polymerase and can be found in standard texts, e.g. Berg et al. Figure 5.22
The reaction mechanism. This reaction is catalysed by an enzyme which participates in the reaction. The mechanism of catalysis is summarized on the EBI facility (where diagrams can be found) as:
RNA polymerases catalyse the nucleophilic attack of a bound nucleoside
5′-triphosphate by the 3′-hydroxyl of an RNA primer, resulting in the
incorporation of a nucleoside monophosphate into RNA and the release
of pyrophosphate. This is thought to occur using two-metal catalysis.
In RNA polymerase II, two magnesium ions are coordinated by four
aspartates (3′OH of RNA also proposed to weakly coordinate to Mg2+A).
Mg2+A is proposed to lower the pKa around the attacking hydroxyl while
Mg2+B is there to stabilise the negative charges during transition
The thermodynamics of the reaction. The breaking of one phosphodiester bond and the formation of another means that the reaction is more or less at equilibrium (no change in Gibbs Free Energy). One reason that it is thought not to reverse is because the pyrophosphate produced is hydrolysed in the cell to orthophosphate, which is irreversible as the free energy change in this reaction is lost as heat.
Hydrogen Bonding to the template. The reaction involves copying a template strand, and the basis of this specificity is Watson–Crick hydrogen bonding between template base and incoming NTP. However, specifically for the VPg primer, there is hydrogen bonding of the two U residues to the end of the template strand. (Diagrams of AU hydrogen bonding should be easy to find.)
The chemical linkage of the VPgUU primer. The uridylic acid residues are added to the VPg peptide at the hydroxyl group of a tyrosine residue in a reaction that is catalysed by the viral RNA polymerase. It is worth noting that although many amino acid residues of proteins are chemically inert, the hydroxy amino acids have reactive potential, most notably in being phosphorylated.
A broader point for reflection
One question that this raises is why the need for a protein — VPg — as adjunct to a nucleic acid primer. Reading further on the subject will reveal this protein actually interacts with different parts of the viral RNA in the course of acquiring the Uridylate residues and selecting the AA where it should bind. The chemical interactions with RNA and other proteins here are the weak non-covalent interactions — hydrogen bonds, van der Walls interactions and some ionic interactions — that are typical of proteins. Rather than their weakness being a reason for considering them unimportant, such interactions are crucial to the chemistry of life because their very weakness means that they can be both broken as well as made. The interactions are reversible, leading to the very dynamic property that typifies life. They are worthy of a chemist’s attention.