Chapter 13: Viruses, Viroids, and Prions

Comprehensive vocabulary flashcards covering the structure, replication pathways, genetics, and classification of viruses, viroids, and prions based on Chapter 13.

Virus

An infectious particle containing DNA or RNA surrounded by a protein coat that must enter a living host cell to reproduce.

Viroid

Small, circular piece of RNA without a protein coat that mainly infects plants.

Prion

An infectious misfolded protein that contains no DNA or RNA and causes serious neurological diseases.

Virion

A complete virus particle.

Capsid

The protein coat surrounding viral DNA or RNA.

Capsomeres

Protein units that make up the viral capsid.

Envelope

An outer membrane present on some viruses.

Spikes

Structures that help viruses attach to host cells.

Helical

A spiral-shaped virus structure.

Polyhedral

A many-sided viral shape.

Complex virus

A virus exhibiting a more complicated structure than simple helical or polyhedral shapes.

Antigenic drift

Small mutations occurring in a virus over time.

Antigenic shift

Major genetic change resulting from the mixing of genetic material.

Bacteriophage

A virus that infects bacteria.

Lytic cycle

Viral replication cycle where the virus makes copies and destroys the host cell.

Lysogenic cycle

Viral cycle in which viral DNA joins bacterial DNA and stays inactive.

Prophage

Viral DNA integrated inside bacterial DNA.

Induction

The process by which a prophage becomes active and enters the lytic cycle.

Lysis

The process in which the host cell breaks open to release new viruses.

Budding

Process by which a virus leaves the host cell through the cell membrane.

Positive-sense RNA (+)

Viral RNA that can act directly like mRNA.

Negative-sense RNA (−)

Viral RNA that must be copied into positive RNA first before translation.

Retrovirus

A virus that uses reverse transcriptase to synthesize DNA from RNA.

Reverse transcriptase

An enzyme that performs reverse transcription ($\text{RNA} \rightarrow \text{DNA}$).

Provirus

Viral DNA integrated into the host cell's DNA.

Latent infection

A condition where the virus stays inactive inside the host and can reactivate later.

Persistent infection

An infection in which the virus remains continuously in the body over time.

Hepatitis A

A type of hepatitis mainly transmitted via contaminated food or water.

Hepatitis B

A type of hepatitis transmitted through blood and body fluids.

Hepatitis C

A type of hepatitis transmitted mainly through blood.

Virusoid

Small RNA that needs a helper virus to establish infection.

PrPᶜ

The normal cellular form of the prion protein.

PrPˢᶜ

The infectious, misfolded form of the prion protein.

TSE

Transmissible spongiform encephalopathy; a group of serious neurological diseases caused by prions.

Host range

The specific cells or organisms that a particular virus is capable of infecting.

Eclipse period

The time during viral infection when complete, infectious viruses cannot be detected inside the host cell.

Phage conversion

A phenomenon where infection by a virus changes bacterial characteristics.

Reassortment

The mixing of viral genome segments.

Oncogene

A gene that can contribute to the development of cancer.

Transduction

The transfer of bacterial DNA from one bacterium to another by a virus.