Microbiology Chapter 13: Viruses, Viroids, and Prions

Vocabulary practice flashcards covering bacteriophage and animal viral replication cycles, genetic strategies, entry and release mechanisms, and retroviral biosynthesis based on Chapter 13.

Bacteriophage

A virus that infects bacteria; also commonly referred to as a phage.

Lytic cycle

A viral multiplication cycle in which the bacteriophage causes lysis and death of the host cell.

Lysogenic cycle

A viral reproductive cycle in which the phage genome integrates into the host bacterial chromosome and remains latent without immediately causing cell lysis.

Prophage

Bacteriophage DNA that is stably inserted and integrated into the host cell's chromosome.

Phage conversion

The acquisition of new properties or phenotypic traits by a host bacterium as a result of harboring a prophage.

Transduction

The transfer of host chromosomal DNA from one bacterial cell to another mediated by a replicating bacteriophage.

Phage lysozyme

An enzyme produced by bacteriophages that degrades bacterial cell wall peptidoglycan during both viral penetration and host cell lysis at release.

Penetration (T-even bacteriophage)

The stage of infection where phage lysozyme digests an opening in the cell wall, and the tail sheath contracts to inject viral DNA through the tail core into the host cell.

Maturation (viral multiplication)

The assembly phase of viral multiplication during which newly synthesized viral genomes and capsid proteins are assembled into complete virions.

Receptor-mediated endocytosis

An entry mechanism used by many animal viruses where the virion binds host plasma membrane proteins, triggering inward folding of the plasma membrane to engulf the virus.

Fusion (viral entry)

An entry method used by enveloped animal viruses where the viral lipid envelope coalesces directly with the host plasma membrane, releasing the capsid into the cytoplasm.

Uncoating

The separation of the viral nucleic acid from its protein capsid by viral or host enzymes; a necessary step for animal viruses that is not required for bacteriophages.

Budding

The release mechanism of enveloped animal viruses where nucleocapsids push outward through the host cell membrane, acquiring a lipid bilayer envelope without immediately lysing the cell.

Sense (+) strand RNA

Viral single-stranded RNA that is oriented identically to mRNA and can be translated directly into viral proteins by host ribosomes.

Antisense (−) strand RNA

Viral single-stranded RNA complementary to mRNA that must first be transcribed into a positive-sense (+) strand before viral proteins can be synthesized.

RNA-dependent RNA polymerase

A viral enzyme utilized by RNA viruses to transcribe complementary RNA strands and replicate their RNA genome within the host cell cytoplasm.

Reverse transcriptase

An enzyme carried by retroviruses that copies viral single-stranded RNA to synthesize complementary double-stranded DNA.

Provirus

Viral DNA synthesized by reverse transcription that is permanently integrated into a eukaryotic host cell chromosome by viral integrase.

Viral integrase

The retroviral enzyme that facilitates the transport of viral double-stranded DNA into the host nucleus and integrates it into the host chromosome as a provirus.

Viral protease

A retroviral enzyme that cleaves and processes precursor viral polypeptide proteins into functional components during maturation.

Retroviridae

A family of enveloped, positive-strand RNA viruses—including Lentivirus (HIV) and oncoviruses—that replicate via a DNA intermediate using reverse transcriptase.