Video - Viral structure and functions

Viruses are a unique type of pathogen that lack cytoplasmic membrane, cytosol, or functional organelles and use the metabolic machinery of host cells to produce more viral molecules. They can exist extracellularly as a virion or intracellularly as nucleic acids that induce the host to synthesize viral components. Viruses come in many shapes and sizes, including helical, icosahedral, and complex. The viral genome can be DNA or RNA, single-stranded or double-stranded, and mutations in RNA viruses occur more frequently than in DNA viruses due to the likelihood of transcription errors by RNA polymerases.