CORONA VIRIDAE-Properties of Coronaviridae

STRUCTURE AND COMPOSITION :-                                           

 The unicellular microorganisms can he arranged in order of decreasing size and complexity; protozoa, fungi, and bacteria- the latter including mycoplasma, rickettsiae, and chlamydiae, which, like viruses, replicate within eukaryotic ,cells. These microorganisms, however small and simple, are cells.

They always contain DNA as the repository of genetic information, they also contain RNA, and they have their own machinery for producing energy and macrcomolecules.Unicellular microorganisms grow by synthesizing their own macromolecules constituents (nucleic acid, protein, carbohydrate, and lipid), and most multiply by binary fission.

Viruses, on the other hand, are not cells. They possess no functional organelles and are completely dependent on their cellular hosts For the machinery of energy production and synthesis of macromolecules. They contain only one type of nucleic acid, either DNA or RNA, but never both, and they differ from non viral organisms in having two clearly defined phases in their life cycle. 

Outside a susceptible cell, the virus particle is metabolically Inert, if is the transmission phase of the virus. This extracellular transmission phase alternates with an intracellular reproductive phase, in which the viral genome exploits the metabolic pathways of the host to produce progeny genomes and viral proteins that assemble to form new virions. Further, its like any unicellular microorganism, many viruses can reproduce themselves even if nothing but the viral genome is introduced into the cell

The key differences between viruses and unicellular microorganisms are listed. Several important practical consequences flow from these differences. For example, some viruses can persist in cells by integration of their DNA (or a DNA copy of their RNA) into the genome of the host cell.