Chapter 13 Study Guide: Characterizing and Classifying Viruses, Viroids, and Prions

These flashcards cover the fundamental aspects of viruses, viroids, and prions, including their structures, replication mechanisms, and the diseases they cause.

Viruses

Infectious agents composed of a nucleic acid core (DNA or RNA), a capsid, and sometimes an envelope.

Capsid

A protein coat made of subunits called capsomeres that encases the viral nucleic acid.

Naked Virus

A virus without an envelope, more resistant to environmental factors such as drying and heat.

Enveloped Virus

A virus that has a lipid envelope, which makes it more sensitive to external conditions.

dsDNA

Double-stranded DNA virus that utilizes the host's DNA and RNA polymerases.

ssDNA

Single-stranded DNA virus that must synthesize a complementary strand before replication.

+ssRNA

Single-stranded RNA virus that acts directly as mRNA for translation.

−ssRNA

Single-stranded RNA virus that must be converted into +ssRNA by RNA-dependent RNA polymerase.

dsRNA

Double-stranded RNA virus that requires RNA polymerase to synthesize mRNA.

Retroviruses

Viruses that use reverse transcriptase to convert RNA into DNA, such as HIV.

Host Specificity

The ability of a virus to infect specific host cells based on the compatibility of virus receptors.

Lytic Cycle

A viral replication cycle involving attachment, penetration, biosynthesis, maturation, and release, leading to host cell death.

Lysogenic Cycle

A viral replication cycle that involves integration of viral DNA into the host genome, remaining dormant until activation.

Viroids

Small, infectious agents composed of naked, circular RNA molecules that exclusively infect plants.

Prions

Infectious proteins with no nucleic acids that cause other proteins to misfold, leading to neurodegenerative diseases.

Spongiform Encephalopathies

Diseases caused by prions that result in brain tissue damage, creating holes in the brain.

Creutzfeldt-Jakob Disease (CJD)

A human prion disease that leads to rapid neurodegeneration.

Bovine Spongiform Encephalopathy (BSE)

A prion disease in cattle known as Mad Cow Disease.