Viroids, Viruses and Bacteria are classified as Microbes. Generally, Microbes are living organisms that can’t be visible through the naked eye. in this post, we will learn all the important points of them.
Viruses did not find a place in classification since they are not truly ‘living’ if we understand living as those organisms that have a cell structure.
Viruses are non-cellular organisms that are characterized by having an inert crystalline structure outside the living cell.
Viruses are obligate parasites. Once they infect a cell, they take over the machinery of the host cell to replicate themselves, killing the host.
The name virus which means venom or poisonous fluid was given by Pasteur.
In addition to proteins, viruses also contain genetic material, which could be either RNA or DNA.
No virus contains both RNA & DNA.
In general,
viruses that infect plants have single-stranded RNA &
viruses that infect animals have either single or double-stranded RNA or double-stranded DNA
bacteriophages (viruses that infect bacteria) are usually double-stranded DNA viruses.
The protein coat called capsid made of small subunits called capsomeres protects the nucleic acid.
These capsomeres are arranged in helical or polyhedral geometric forms.
Types of Viruses
Viruses cause diseases like mumps, smallpox, herpes & influenza. AIDS is also caused by a virus.
In plants, the symptoms can be mosaic formation, leaf rolling & curling, yellowing & vein clearing, dwarfing & stunted growth.