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A virus has either a DNA or an RNA genome and is called a DNA virus or an RNA virus, respectively. The vast majority of viruses have RNA genomes. Plant viruses tend to have single-stranded RNA genomes and bacteriophages tend to have double-stranded DNA genomes.
Best Answer: There is a wide variety of virus structures, but all of them carry two elements in common. (1) They have a DNA or RNA genome, and (2) they have a protein coat, or capsid, that protects this genome from the environment. just now. Report Abuse. A virus (from the Latin virus meaning toxin or poison) is a sub-microscopic infectious agent that is unable to grow or reproduce outside a host cell. Each viral particle, or virion, consists of genetic material, DNA or RNA, within a protective protein coat called a capsid.