Virus Reproduction: Understanding the Paradox

[mktsgm]

TL;DR

Are viruses alive? If not why they reproduce?

Science believes that a virus does not have life. They do not display any of the properties of 'life' such as homeostasis - they lack, growth - they don't grow, response to stimuli - they don't respond etc.

i.e., They're not as alive as bacteria, animals, humans. If so, how come they want to reproduce? Why would a lifeless creature want to reproduce? Do they have an intention to infect, procreate/reproduce in other animals?

How can we understand this paradox?

 

[BillTre]

Opinions vary on whether viruses should be considered alive or not.
It often comes down to how you define alive. There are many different definitions of what is required to be alive.
An alternative approach is to consider whether things exhibit a living process or not. This might allow viruses to have a living state when in a cell reproducing and not having a living state at other times.

they don't grow

They do grow and reproduce when they infect cells.

response to stimuli

They do respond to stimuli when they bind to components of a cell's surface to gain entry to the cell.

You might consider them alive only when they are in the proper environment (the inside of a cell) for most of their activities to occur. This is the environment they were selected to reproduce in. The outside of the cell environment is one in which they were selected to survive in with the least expenditure of energy. Thus they don't do much and wait for the proper signal to become active. This is similar to an inactive seed. Both an inactive seed and a virus (not in a cell) are just sitting there and waiting for the right triggering event(s) to send them into their next stage of activity (virus: reproducing; seed: sprouting).

Viruses, like many organisms (without nervous systems), don't have intentions or want to do things. They just do them in a mechanistic manner, like when my computer reproduces a document.

 

[jim mcnamara]

You are kind of assigning human values and traits to something that is purely biochemical in nature.

I'm going to make an analogy, that does not mean it is a true statement, just a way to understand, okay? I'm not getting all of the details letter perfect. You want that? ...read the linked article.

Living cells are like automobiles, that have lots of parts that do different jobs, except the workbench is basically the same for living all things. That workbench is made of different flavors of a molecule called RNA (mRNA, tRNA, etc). Automobiles have a workbench too, the internal combustion engine. But cars come with all kinds of other things, like wheels and complex rulkes for us to follow so we reduce the chance of killing our fellow motorists.

Viruses cheat. All they have is a set of rules. No machinery. No workbench. They have simple plans that create new virus particles-- complete with the special protein shell coating around DNA/RNA that gives the virus access to new cells. Plus RNA instructions (or DNA instructions) for messing up cell machinery. Viruses are VERY small. A simple coat and a few genes. No organelles like a nucleus or endoplasmic reticulum.

They get into a cell and the take over the infected cell, and turn it into a virus factory. So with one virus in command of one cell , it makes 500 viruses and then the cell runs out of fuel, dies, and bursts. The viruses spill out. Infect more cells, thet burst too. Soon there are millions of viruses. While they are making the cells into bursting slaves they may also disrupt other things which cause the cells to release bad products that go out with the burst of cell goo. The bad products do things like create disruption - sneezing, fever, coughing, etc. - for the whole creature. The virus gets a free ride out of the creature it is in. Us.

This makes it easy for viruses to kill of lots of cells, and at the same time create a good way to get the new viruses out into the world of fresh living cells in another creature.

Natural selection works on viruses, too. That is why many viral diseases are moving targets for companies that make antiviral vaccines.

So. Would you call a set of sinister plans wrapped in protein alive? No. In a lab, create pure tobacco mosiac virus particles, lots of it, make a suspension, let it dry and get crystals. 20 years later you add water to crystals, put the water on a plant and bingo the plant dies from the viral infection.

See this (lots of pictures):
https://pdb101.rcsb.org/motm/109

 

[mktsgm]

Thank you Jim.