Chapter 13 Viruses, Viroids, and Prions

Flashcards covering key vocabulary and concepts from the Viruses, Viroids, and Prions chapter.

Viruses

Differ from bacteria because they are not composed of cells.

Nonliving Chemicals (Viruses)

Cannot reproduce themselves outside a host.

Viral Spikes

Composed of carbohydrate-protein complexes, used for attachment, may cause hemagglutination, and bind to receptors on the host cell surface.

Virus Classification

Classified based on morphology, nucleic acid, size, and number of capsomeres.

Virus Culture

Utilizes laboratory animals, embryonated eggs, animal cell cultures, and bacterial cultures.

Lysogeny

Phage DNA is incorporated into host cell DNA.

Viroid

Infectious piece of RNA without a capsid.

Plaque

A clear area against a confluent 'lawn' of bacteria.

Continuous Cell Lines

Can be maintained through an indefinite number of generations.

Prion Replication

Requires PrPSc.

Persistent Infection

Disease process occurs gradually over a long period.

Prophage

Phage DNA inserted into a bacterial chromosome that can 'pop' out, resulting in new host cell properties and immunity to infection by the same phage.

Viral Biosynthesis (- strand RNA)

First step is the synthesis of double-stranded RNA from an RNA template.

Infectious Protein

Prion.

Envelope Acquisition

Occurs during release.

Latent Viral Infection

Cold sores.

Virus Infectivity

Depends primarily upon the presence of receptor sites on the cell membrane.

Enveloped Virus Release

Budding.

Conclusive Cancer Evidence

Cancer following injection of cell-free filtrates.

Bacteriophages derive from the host cell:

tRNA, amino acids, nucleotides, and ATP.

Bacteriophage replication differs from animal virus replication

Because only bacteriophage replication involves injection of naked nucleic acid into the host cell.

DNA-virus replication

The host animal cell supplies RNA polymerase, nucleotides and tRNA.

Order for DNA-virus replication

DNA synthesis, transcription, translation, and maturation.

Viral Species

Has the same genetic information and ecological niche.

Reverse Transcriptase Utilizing Viruses

Retroviridae and Hepadnaviridae.

Lytic Virus

Causes the death of the infected cells in the patient.

Latent Viruses

Infect a cell without causing symptoms.

Herpesviruses Multiplication - third step:

Uncoating.

Retroviruses Multiplication - fourth step:

Synthesis of double-stranded DNA

Oncogenic Viruses

Cause tumors to develop.

Early Gene Product

DNA polymerase.

Antigenic Shift in Influenza Viruses

Segmented genome.

Oncogenes

First identified in cancer-causing viruses and can induce transformation in infected cells.

Positive sense RNA

Strands of viruses are treated like mRNA inside the host cell.

Segmented genome

Can result in antigenic shift.