Viruses

Vocabulary

assembly

fifth step in the virus life cycle, in which new viruses are created by packaging of the replicated genome into capsids

attachment

first step in the virus life cycle, in which a virion attaches to a host cell's surface

capsomere

collection or assembly of protein molecules making up a viral capsid

cytopathic effect

virus-induced structural change in a host cell that results in cell death, either through lysis (rupture) or inability to reproduce

endocytosis

form of bulk transport that moves material into a cell by an infolding of the cell membrane around the material, forming a vesicle (small sac) that moves into the cell

exocytosis

form of bulk transport used to move material outside the cell by fusion of a vesicle with the plasma membrane and release of the contents outside the cell

genome

genetic material of an organism

helical

type of symmetry of capsomere arrangement associated with spiral-shaped viruses

host range

range of cells—the types of organisms—that can host a virus

icosahedron

roughly spherical geometric structure with 20 triangular faces and the most efficient arrangement of capsomeres in a viral capsid

lysogenic conversion

transfer of genetic information from one bacterial host cell to another by a lysogenic virus

lysogeny

state in which most viral genes in a host cell are dormant and the viral genome (provirus) and host chromosome are integrated and replicated together

oncogenic

causing tumors to develop. With certain viruses, the effect occurs in host cells.

oncolytic viral therapy

a medical treatment that uses a modified virus to induce cell death (lysis) in tumors

penetration

second step in the virus life cycle, when the virion enters or injects its nucleic acid into the host cell

prion

misfolded and infectious protein

provirus

genome of a virus in the lysogenic life cycle that is incorporated and replicated with the host chromosome

release

sixth and final step of the virus life cycle, when mature viruses leave the host cell

reverse transcriptase

enzyme that uses RNA as a template to make a DNA copy

synthesis

fourth step in the virus life cycle. It occurs when the virus directs the host cell's metabolism to produce the virus's nucleic acid and capsid protein.

uncoating

process that occurs in enveloped viruses when the virion enters a host cell and viral DNA or RNA is freed from the capsid and viral envelope

vaccination

technique of exposing an organism to a form of a pathogen to develop immunity against it

viral budding

process by which a mature virion leaves a host cell, borrowing contents of the host membrane to build its viral envelope as it exits

viral capsid

protein coat surrounding and protecting the viral genome

viral envelope

structure that consists of lipid-containing layers that surround the nucleocapsid of a virus

viral transformation

change to the host cell's physiology, biochemistry, or genetics because of the introduction of viral genetic information

virion

extracellular form of a virus which functions independently of a host

viroid

the smallest identified infectious agent composed simply of circular, single-stranded RNA without a protein coat

virus

infectious agent consisting of a nucleic acid strand within a protein coat