why isn't it possible for viruses to grow on agar?

Answer 1

Bacteriophages can grow on agar (viruses that are specific to bacteria) if you culture them on a plate with a lawn of the host bacteria your virus is specific for and its measured by the depletion of cells observed as "plaques" (clear spots in the lawn of bacteria). Viruses specific to animals can only be cultured on cell plates because they don't survive through the need of nutrients and so forth, they have a specific mode of existence and its solely molecular. So basically, it needs the cell's gene expression machinery to now make the viruses own proteins that encodes for all the structural protein and genetic material of a new virus and uses this to replicate itself. It only exists to reproduce. So, unless your plate has live polymerases, ribosomes, ATP, and proteins involved in replication and gene expression (which is simply not possible at all) then the virus relies on the cell, without it that one virus will remain dormant until a suitable environment presents itself (i.e. injection or contact with a live cell).

Answer 2

it is possible if the nutrient agar has antibiotics in it. if the microbe is an auxotroph (such as a mutant) it will have a nutritional requirement that needs to supplemented in the media. nutrient agar contains beef broth, peptone, and of course agar. most kinds of fungi and bacteria will grow on nutrient agar, but some find it too much -- others find it too deficient. halophilic bacteria for example do not like to grow on nutrient agar.

Answer 3

Does it have anything to do with nutrients. If viruses are accidently placed on agar isnt a bacteriophage formed?

Answer 4

Viruses rely on live cells.

Answer 5

Becuae a virus requires a host cell to reproduce. it has only a genome and coating, and none of the molecular 'machinery' required to replicate those.

Answer 6

Jello?