Plasma Membrane in Prokariotes, Eukariotes, Viruses

"At some point in early evolution [4 billion years ago], life became cellular. Assuming that this step was required for the origin of life, there would necessarily be a pre-existing source of amphihilic compounds capable of assembling into membranous compartments."

"Anyone who has blown a soap bubble has made a self-assembled membrane. Soaps are monocarboxylic acids, and a soap bubble is a metastable structure with a monolayer of ionic fatty acids on the outside and inside surface. The hydrocarbon chains are directed outward, and the hydrophilic head groups stabilize a thin layer of micelles and water on the interior of the membrane. Soap molecules also assemble into microscopic vesicles in aqueous phases, but the membranes are bilayers with the hydrocarbon chains directed inward. Self-assembly of amphiphilic molecules like soap is so common that it is not difficult to imagine that similar molecules, if available, would form membranous compartments on the prebiotic Earth."

"A lipid bilayer is a biological membrane consisting of two layers of lipid molecules. Each lipid molecule, or phospholipid, contains a hydrophilic head and a hydrophobic tail. The tail regions, being repelled by water and slightly attracted to each other, congregate together."

"The bilayer structure is attributable to the special properties of the lipid molecules, which cause them to assemble spontaneously into bilayers even under simple artificial conditions."

"Cells fall into one of two broad categories: prokaryotic and eukaryotic. The predominantly single-celled organisms of the domains Bacteria and Archaea are classified as prokaryotes (pro– = before; –karyon– = nucleus). Animal cells, plant cells, fungi, and protists are eukaryotes (eu– = true)."

"The oldest evidence of eukaryotes is from 2.7 billion years ago. Scientists believe that a nucleus and other organelles inside a eukaryotic cell formed when one prokaryotic organism engulfed another, which then lived inside and contributed to the functioning of its host."

They both do have a membrane made of a lipid bylayer. The "housing" of every living cell. However prokaryotes have an extra cell wall.

"Cell Walls: Most prokaryotic cells have a rigid cell wall that surrounds the plasma [lipid bylayer] membrane and gives shape to the organism. In eukaryotes, vertebrates don't have a cell wall but plants do." Jul 11, 2019

Here is a diagram of an eukariote focused on the membrane. You can see the two layers of phospholipids (with red "heads") that stay together by means hydration repulsion , hydrophobic attraction and van der Waals forces. It is this combination of forces and existence of polar phospholipids that makes possible all life.

However, as stated above, eukariotes in vertebrates lack a cell wall. To protect the fragile lipid bylayer they have to secrete a protective layer of proteins, mainly collagen, that forms what we call the extracellular matrix.

Antibiotics rely on the fact that bacteria are prokaryotes and have a cell wall (with some exceptions, but those are parasitic or live only inside host cells) and animal cells are eukaryotes. They prevent building of new bacterial cell wall made of peptidoglycan after bacterial (cellular) division. New bacteria cannot survive without a cell wall as they can't secrete an extracellular matrix.

Viruses are not cells. They are a molecular structure made of a lipid bylayer with binding proteins on the outside, ARN fragments and proteins (sometimes in a capsid) on the inside and they lack both cell walls as in prokaryotic cells and extracellular matrix as in eukaryotic cells.

Question. How coronaviruses "survive" in the environment, outside and inside of a host, without a cell wall or an extracellular matrix?

One possible answer is when they leave the host they can only "survive" inside fragments of extracellular matrix from damaged areas of the body or engulfed in mucus secretions.