bio 1202 ch19 - viruses

human immunodeficiency virus (HIV)

The infectious agent that causes AIDS. It is a retrovirus

pandemic

A global epidemic

virus

An infectious particle

incapable of replicating

outside of a cell, consisting of

an RNA or DNA genome

surrounded by a protein coat

(capsid) and, for some,

a membranous envelope

prion

An infectious agent that is a

misfolded version of a normal

cellular protein. They appear

to increase in number by

converting correctly folded

versions of the protein to

more of themselves

phage

A virus that infects bacteria;

also called a bacteriophage

virulent phage

A phage that replicates only by

a lytic cycle

prophase

The first stage of mitosis, in

which the chromatin condenses

into discrete chromosomes

visible with a light microscope,

the mitotic spindle begins to

form, and the nucleolus

disappears but the nucleus

remains intact

epidemic

A widespread outbreak of a

disease

temperate phage

A phage that is capable of

replicating by either a lytic or

lysogenic cycle

bacteriophage

A virus that infects bacteria;

also called a phage

restriction enzyme

An endonuclease (type of

enzyme) that recognizes and

cuts DNA molecules foreign to a bacterium (such as phage

genomes). The enzyme cuts at

specific nucleotide sequences

(restriction sites)

viral envelope

A membrane, derived from

membranes of the host cell, that cloaks the capsid, which in turn encloses a viral genome

reverse transcriptase

An enzyme encoded by

certain viruses (retroviruses)

that uses RNA as a template

for DNA synthesis

capsid

The protein shell that encloses

a viral genome. It may be

rod-shaped, polyhedral, or

more complex in shape

host range

The limited number of species

whose cells can be infected by

a particular virus

vaccine

A harmless variant or derivative

of a pathogen that stimulates a

host's immune system to mount

defenses against the pathogen

lysogenic cycle

A type of phage replicative

cycle in which the viral

genome becomes

incorporated into the bacterial

host chromosome as a

prophage, is replicated along

with the chromosome, and

does not kill the host

lytic cycle

A type of phage replicative

cycle resulting in the release

of new phages by lysis (and

death) of the host cell

endemic

Referring to a species that is

confined to a specific

geographic area

retrovirus

An RNA virus that replicates

by transcribing its RNA into

DNA and then inserting the

DNA into a cellular

chromosome; an important

class of cancer-causing viruses

provirus

A viral genome that is

permanently inserted into a

host genome