Question

The Coronavirus disease 2019 (COVID-19) is an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This type of RNA virus causes diseases by replicating only inside the living cells of an organism like mammals and birds. When not inside an infected cell, viruses behave mostly as inert things (e.g., do not self-replicate, do need energy to exist and might crystallize). What traits, common to living things, might define SARS-CoV-2 as a living organism? Define at least 4 principles.

Answer 1

1. SARS-CoV-2 have RNA as their genetic material. Some of the very first life-forms on Earth were RNA molecules. RNA molecules, under the right conditions, can make copies of themselves. It is said that viruses might have evolved from that ancestor, but lost the capability to self-replicate.

2. It is said that living things have different level of organization. In live organisms usually smaller building blocks come together to make a larger product. Similarly in case of SARS-CoV-2, they have genes made from nucleic acids and a capsid made of smaller subunits called capsomeres.

3. Another criteria for living things is that they reproduce. In case of SARS-CoV-2 we can say that, since they don’t have organelles, nuclei, or even ribosomes, they don’t have the tools they need to copy their genes. Therefore, they enter living cells and then hijack the host’s cellular machinery to copy viral genetic information, build new capsids, and assemble everything together. Thus, viruses replicate, instead of reproduce, as they need a host cell to multiply.

4. It is said that living things adapt to their environment. Adaptation occur through mutations. Virus also mutate easily. Very recent studies have reported that there are about 198 sites in the SARS-CoV-2 genome that have already undergone recurrent, independent mutations based on a large-scale analysis of public genome assemblies.