IB Biology Topic A2.3: Viruses Key Definitions

Gradual accumulation of point mutations in surface proteins, which creates new viral variants.

A sudden genetic reassortment occurs when two different viral strains infect the same host cell, producing a radically new subtype.

Convergent evolution is when distantly related organisms independently evolve similar traits or behaviors to adapt to similar environments

Horizontal gene transfer involves the direct exchange of genetic material between unrelated organisms, bypassing traditional parent-offspring inheritance. It is especially common in prokaryotes (bacteria and archaea).

The sum of all chemical reactions occurring in an organism to maintain life, including reactions that break down molecules for energy (catabolism) and reactions that build molecules for growth and repair (anabolism).

An RNA virus that uses reverse transcriptase to produce DNA, which then integrates into the host genome.

The lytic cycle is a viral replication process during which a virus infects a host cell, takes control of its machinery to produce new viral particles, and ultimately causes the host cell to burst (lyse), releasing the newly formed viruses.

A virus is a non-cellular particle composed of genetic material (DNA or RNA) enclosed in a protein coat called a capsid.