Viruses Slideshow

Virus

An infectious particle consisting of genes packaged in a protein coat that lacks machinery and structures found in cells.

Capsid

The protein shell of a virus that surrounds its genetic material.

Bacteriophage

A virus that infects bacteria, almost all of which have DNA genomes.

Host range

The limited number of host species that a virus can infect.

Lytic Cycle

The virus replication cycle that ends in the death of the host cell, causing the cell to lyse.

Lysogenic Cycle

A phase in the life cycle of a virus that allows replication of the viral genome without destroying the host cell.

Retrovirus

A virus that contains two identical ssRNA strands and uses reverse transcriptase to form DNA.

Viroid

A circular RNA molecule that infects plants and does not encode proteins but can replicate.

Prion

Infectious proteins that convert normally folded proteins into misfolded aggregates, interfering with normal protein function.

Envelope

A membrane surrounding the capsid of some viruses, derived from the host cell membrane.

dsDNA viruses

Viruses that use both viral and cellular enzymes to replicate within the host.

ssRNA viruses

Viruses whose RNA can either serve directly as mRNA or be used as a template to produce mRNA.

Provirus

Viral dsDNA integrated into the host DNA that never leaves the host's genetic material.

Environmental signal

A trigger that switches a lysogenic bacteriophage into the lytic cycle.

Viral glycoproteins

Proteins on the envelope of animal viruses that bind to specific receptor molecules on host cells.

Mutant receptors

Altered receptors in bacteria that allow for survival against bacteriophages.