In a former life I studied the sciences leading to a degree in Biochemistry. As part of my studies I took a course in virology, my main interest was molecular genetics so it was mainly from a genetic perspective. I found viruses absolutely fascinating and totally amazing things. Now, my knowledge is 35 years out of date and things have moved on apace, but I’m sure I still have a grasp of the basics. So, just in case you’re interested here is a layman’s guide to viruses, what they are, and how they work:
Most viruses are a string of RNA (a very few are DNA) encased in a protein envelope. It is very difficult to argue that they are ‘alive’ in any meaningful way: they do not respire, they cannot move, they have no cell structure, they do not eat, and they can’t even reproduce themselves. So, what do they do? Well, they are extremely successful at multiplying, not by themselves, but using the reproductive mechanism of host cells.
First, a primer in DNA, RNA and protein. You will know DNA is made of two long strands wound together in opposite directions, the ‘double helix’. Each strand is made up of a string four distinct type of DNA molecule. These are given the names A, T, G and C. Each strand of DNA in the helix is a mirror image of the other, A pairs with T and G with C. The DNA resides in the nucleus of the cell (with the exception of mitochondrial DNA, but that’s another story) all coiled up, as chromosomes. In order to make proteins the DNA is ‘read’ in the nucleus to produce RNA which is then transported into the main part of the cell to be ‘expressed’. RNA is a single strand made of a combination of RNA molecules called A, U, G and C. The RNA is read in groups of three ‘bases’, each group of three represent a single amino acid. So, RNA is read to produce a string of amino acids, which we call proteins. So, genetic information is stored in DNA from which RNA carries the code to the ‘workshop’ of the cell to produce proteins. It is worth reflecting here that the sequence of A, T, G and C in DNA encodes the entirety of nature, every animal, fish or reptile; every bacteria, mollusc or flee; every tree, plant or algae. All share the same ‘code’ stored on their DNA. Not surprising since they all have the same creator.
So, the sequence is: DNA à RNA à Protein. During cell replication (mitosis) DNA is replicated to produce two sets of chromosomes which then form two cells. And the process begins again.
Back to viruses. A virus will attach itself to a cell wall, bear in mind they are extremely tiny compared to a cell, which itself is extremely tiny. Viruses are so tiny that you can’t see them without an electron microscope. This explains why face masks are of little use, viruses simply pass straight through them. Having attached itself the virus injects its RNA into the cell. This RNA is then expressed by the cell to produce proteins making up the protein ‘envelope’ of the virus. But, how is the RNA duplicated? Well I’m glad you asked, because here is the really clever bit. On the RNA is coded a protein which, when expressed, makes an enzyme that puts things in reverse making DNA from RNA! This DNA is then read by the cell workshop to produce RNA – more viruses! Eventually so many new copies of the virus are made that the cell wall breaches, spilling out the viruses to begin the process again in other cells. And so it goes on.
What are viruses? Tiny pieces of the molecule that makes living things. They are not life in any way we could recognise. They simply reflect the shear fecundity of the very fabric of creation.
I do hope this helps!