7 Viruses and Other Acellular Agents Free Online FlashCards

What is a virion?

A virion is a complete infectious viral particle outside a host cell.

What kind of genome does a virus contain?

A virus has either a DNA genome or an RNA genome, not both as the genome of a single virus.

What is a viral capsid?

A capsid is the protein shell that encloses a viral genome.

What makes up a nucleocapsid?

The nucleocapsid is the viral genome together with its capsid.

How does an envelope affect a virus?

Viral envelopes are lipid membranes acquired from host-cell membranes. Enveloped viruses are generally more sensitive to drying, heat, detergents, and solvents that disrupt lipids.

What determines a virus's Baltimore group?

The Baltimore system groups viruses by genome type and how they produce messenger RNA (mRNA), which host ribosomes translate into protein.

How do positive- and negative-sense viral RNA differ?

Positive-sense RNA can function as mRNA; negative-sense RNA must first be copied into a complementary positive-sense strand.

How do ICTV taxonomy and Baltimore classification differ?

ICTV taxonomy organizes viruses into formal hierarchical taxa using multiple biological and evolutionary characteristics. The Baltimore system instead groups them by genome type and mRNA production route.

What are the main stages of a viral replication cycle?

A typical cycle proceeds through attachment, entry, uncoating, genome expression and replication, assembly, and release.

What happens during a phage's lysogenic state?

In a lysogenic state, a phage genome is maintained in its host, sometimes integrated into the chromosome, and copied as the host divides. It can later switch to productive replication.

What is viral latency?

Latency is persistence in animal cells with little or no production of infectious particles, potentially followed by later reactivation.

What determines a virus's host range?

Host range is the set of host species and cell types a virus can infect. It depends on cell entry and whether the cell provides compatible conditions and machinery for replication.