Viruses, V

Notes

Viruses, Viroids, and Prions •Viruses What is a Virus? A nonliving particle containing a nucleic acid genome (DNA or RNA). Despite their simplicity, viruses display great diversity. Characteristics Shared by All Viruses All rely on a living cell for replication, are very small, and exhibit diverse structures. Viral Diversity Viruses differ in host range, basic structure, and genome composition (DNA or RNA, single-stranded or double-stranded, linear or circular). •Host Range A host species is a species that a specific virus can infect. The range of species a virus can naturally infect is called its host range, which includes the number of species and cell types a virus can infect. •Viral Structure Viruses are nonliving particles with a genome of nucleic acids and a capsid (protein coat). Capsids can be helical (e.g., tobacco mosaic virus) or polyhedral (e.g., adenovirus). Many viruses have specialized proteins, such as spike glycoproteins, that bind to host cell surfaces. •Viral Genomes Viral genomes can be double-stranded DNA, single-stranded DNA, double-stranded RNA, or single-stranded RNA. •Viral Reproductive Cycle - Attachment: The virus binds to a host cell surfa...