Do viruses have cells?

All viruses have a protein coat that protects these genes, and some are wrapped in a viral envelope of fat that surrounds them when they are outside a cell. (Viroids do not have a protein coat and prions contain neither RNA nor DNA). Viruses vary from simple helical and icosahedral shapes to more complex structures. read more

Viruses may have once been small cells that parasitised larger cells. Over time, genes not required by their parasitism were lost. The bacteria rickettsia and chlamydia are living cells that, like viruses, can reproduce only inside host cells. read more

Viruses cannot generate or store energy in the form of adenosine triphosphate (ATP), but have to derive their energy, and all other metabolic functions, from the host cell. They also parasitize the cell for basic building materials, such as amino acids, nucleotides, and lipids (fats). read more

Viruses do not have nuclei, organelles, or cytoplasm like cells do, and so they have no way to monitor or create change in their internal environment. This criterion asks whether an individual virion is capable maintaining a steady-state internal environment on its own. read more

The range of structural and biochemical effects that viruses have on the host cell is extensive. These are called cytopathic effects. Most virus infections eventually result in the death of the host cell. The causes of death include cell lysis, alterations to the cell's surface membrane and apoptosis. read more

Since viruses cannot penetrate plant cell walls, virtually all plant viruses are transmitted by insects or other organisms that feed on plants. Certain bacterial viruses, such as the T4 bacteriophage, have evolved an elaborate process of infection. read more