Describe why small and large DNA viruses have evolved varied mechanisms for mRNA production and replication.
There could be observed a significant difference between the genomic size as well as diversity of small and large viruses. According to researchers, large viruses might have been evolved because of (i) gene duplications, (ii) tangential cellular genetic transfers, and (iii) accumulation of various transposons. They further present rationale that well- timed duplication of such a multifaceted genome can become possible only with the assistance of multiple origins of replication. To understand it clearly, we might take example of human genome which replicates in a quick manner owing to presence of numerous origins of replication otherwise; it cannot prove to be competent in terms of fulfillment of our needs.
In the same way, large viruses may require more advanced mechanisms for transcription as well as translation because of their complex life cycles. In fact, due to their specific needs (for example; to control host’s cellular machinery in a temporal manner), they might require considerably variable (in terms of quantity as well as quality) populations of m-RNA and protein molecules. These biomolecules may not be produced and regulated with the aid of simple machinery (for instance; which is present in small viruses) as; there might be needed a complex array of reactions to perform such tasks. The reason behind presence of diverse mechanisms for replication and transcription in small and large viruses can also be understood by considering the role of selection pressure which usually induces biological entities to get evolved via presenting such circumstances that might be termed favorable for this type of transformations.
Because of such induction and further selection by nature, large viruses can be called more potent than small ones and complexity of their genome as well as expression mechanisms may be credited for their host adaptation, pathogenesis and resistance abilities.