Virus | Definition, Structure, & Facts | Britannica
Dec 26, 2024 · Virus, infectious agent of small size and simple composition that can multiply only in living cells of animals, plants, or bacteria. Viruses possess unique infective properties and thus often cause disease in host organisms. Learn about the history, types, and features of viruses.
Structure and features of viruses | Britannica
virus, Microscopic, simple infectious agent that can multiply only in living cells of animals, plants, or bacteria. Viruses are much smaller than bacteria and consist of a single- or double-stranded nucleic acid (DNA or RNA) surrounded by a protein shell called a capsid; some viruses also have an outer envelope composed of lipids and proteins ...
Virus - Structure, Capsid, Genome | Britannica
Dec 26, 2024 · Virus - Structure, Capsid, Genome: The amount and arrangement of the proteins and nucleic acid of viruses determine their size and shape. The nucleic acid and proteins of each class of viruses assemble themselves into a structure called a nucleoprotein, or nucleocapsid.
Virus - Infection, Host, Replication | Britannica
Dec 26, 2024 · Virus - Infection, Host, Replication: Viruses can reproduce only within a host cell. The parental virus (virion) gives rise to numerous progeny, usually genetically and structurally identical to the parent virus.
Virus - Latency, Infection, Replication | Britannica
Dec 26, 2024 · Virus - Latency, Infection, Replication: Inapparent infections (those that do not cause specific signs and symptoms) often result after exposure to picornaviruses, influenza viruses, rhinoviruses, herpesviruses, and adenoviruses but less frequently to measles and chickenpox viruses.
Computer virus | Definition & Facts | Britannica
Nov 23, 2024 · Computer virus, a portion of a computer program code that has been designed to furtively copy itself into other such codes or computer files. It is usually created by a prankster or vandal to effect a nonutilitarian result or to destroy data and program code or, in the case of ransomware, to extort payment.
Virus - Infection, Structure, Replication | Britannica
Dec 26, 2024 · Virus - Infection, Structure, Replication: Although viruses were originally discovered and characterized on the basis of the diseases they cause, most viruses that infect bacteria, plants, and animals (including humans) do not cause disease.
virus - Students | Britannica Kids | Homework Help
A virus consists of a core of nucleic acid surrounded by a protein coat called a capsid; some viruses also have an outer envelope composed of fatty materials and proteins. The nucleic-acid core is the essential part of the virus—it carries the virus’s genes.
virus - Kids | Britannica Kids | Homework Help
Viruses are tiny particles that cause disease in people, other animals, and plants. Different viruses cause the common cold, influenza (flu), chicken pox, measles, AIDS, and many other diseases. Viruses are so tiny that people can see them only with powerful microscopes. Some viruses have a spherical, or round, shape. Others are shaped like rods.
Virus - Protein Capsid, Structure, Infection | Britannica
Dec 26, 2024 · The protein capsid provides the second major criterion for the classification of viruses. The capsid surrounds the virus and is composed of a finite number of protein subunits known as capsomeres, which usually associate with, or are found close to, the virion nucleic acid.