Microbiology: An Introduction - Viruses, Viroids, and Prions

Flashcards covering key vocabulary related to viruses, viroids, and prions from a microbiology lecture.

Virus

Obligatory intracellular parasite that requires a living host cell to multiply; contains DNA or RNA and a protein coat, multiplies using the host cell's machinery, has no ribosomes, and no ATP-generating mechanism.

Host Range

The spectrum of host cells a virus can infect, determined by specific host attachment sites and cellular factors.

Bacteriophages

Viruses that infect bacteria.

Virion

A complete, fully developed viral particle with nucleic acid (DNA or RNA), a capsid made of capsomeres, and sometimes an envelope and spikes.

Capsid

The protein coat of a virus, made of capsomeres (protein subunits).

Envelope

A lipid, protein, and carbohydrate coating external to the capsid in some viruses; derived from the host cell's plasma membrane.

Spikes

Projections from the outer surface of some viruses, made of carbohydrate and protein, used for attachment.

Helical Viruses

Viruses with a hollow, cylindrical capsid that is helical (e.g., rabies and Ebola virus).

Polyhedral Viruses

Viruses that are many-sided, often an icosahedron (20 triangular facets and 12 corners) (e.g., adenoviruses and poliovirus).

Viral Species

A group of viruses sharing the same genetic information and ecological niche (host).

Plaques

Clearings on a lawn of bacteria on the surface of agar, formed by bacteriophages; each plaque corresponds to a single virus (PFU).

Cytopathic Effect (CPE)

Visible changes or deterioration of monolayer cells due to virus infection.

Lytic Cycle

A viral multiplication cycle where the phage causes lysis and death of the host cell (e.g., Tequatrovirus infecting E. coli).

Lysogenic Cycle

A viral multiplication cycle where phage DNA is incorporated into the host DNA without lysis of the host cell.

Prophage

Phage DNA that is inserted into the host cell's DNA during the lysogenic cycle.

Phage Conversion

When the host cell exhibits new properties encoded by the prophage DNA.

Specialized Transduction

Specific bacterial genes transferred to another bacterium via a phage.

Proto-oncogenes

Genes that encode proteins involved in stimulating normal cell growth, which when mutated become oncogenes.

Oncogenes

Mutated proto-oncogenes that transform normal cells into cancerous cells.

Transformation

The process by which cells acquire distinct properties leading to cancer.

Oncolytic Viruses

Viruses used to infect and kill tumor cells or cause an immune response against tumor cells.

Latent Viral Infection

A viral infection where the virus remains in an asymptomatic host cell for long periods and may reactivate (e.g., herpesviruses).

Persistent Viral Infection

A viral infection that occurs gradually over a long period and is generally fatal (e.g., subacute sclerosing panencephalitis).

Prions

Proteinaceous infectious particles that are inherited and transmissible, causing spongiform encephalopathies.