A2.3 (Viruses)

Virus

a non-cellular, microscopic infectious particle that consists of genetic material (DNA or RNA) enclosed in a protein coat called a capsid.

Capsid

the protein coat that encloses the genetic material (either DNA or RNA) of a virus

Bacteriophage

a virus that specifically infects and replicates within a bacterial cell. It generally consists of a polyhedral head, cylindrical tail/collar & tail fibres.

Lytic Cycle

a viral replication process where a virus infects a host cell, uses its machinery to produce new viral particles, and ultimately causes the cell to burst (lyse), releasing the new viruses to infect other cells

Lysis

To cut or break. When referring to a cell it means the disintegration of a cell by rupture of the cell wall or membrane

Metabolism

the sum of all chemical reactions occurring within a living organism.

Lysogenic Cycle

a form of viral replication in which the virus's genetic material integrates into the host cell's DNA and replicates along with it, without immediately harming or destroying the host cell

Prophage

the genome of a temperate bacteriophage (a virus that infects bacteria) that has become integrated into the circular DNA chromosome of a bacterial host cell.

Lysogen

a bacterial cell that has a dormant bacteriophage genome integrated into its own DNA

Parasite

an organism that lives on or in a host organism and gets its food from or at the expense of its host, causing it harm.

Obligate Parasite

an organism that cannot survive or reproduce independently and is entirely dependent on a host for its life cycle

Convergent Evolution

the process where unrelated organisms independently evolve similar traits, such as analogous structures, because they are adapting to similar environmental pressures or ecological roles

Antibodies

Y-shaped proteins produced by plasma cells to neutralize antigens that are recognized as foreign

Antigens

a molecule, typically a protein or polysaccharide, found on the surface of a cell or pathogen that the immune system can recognize as foreign ("non-self") and will trigger an immune response against

Immunity

the body's ability to resist or fight off disease-causing pathogens through specific defense mechanisms

Mutation

A permanant change in the base sequence of DNA

Antigenic drift

the gradual accumulation of point mutations within the genes that code for a virus's surface proteins (antigens)

Antigenic shift

a sudden, major change in the surface antigens of a virus