Chapter 6

Question 1

What is the capsid?

Answer 1

External shell surrounding the virus’s nucleic acids

Question 2

What types of cells can viruses infect?

Answer 2

Bacteria, algae, fungi, protozoa, plants, animals (all types)

Question 3

How are viruses referred to?

Answer 3

As infectious particles that are either active or inactive

Question 4

What are some of the cytopathic effects that can occur?

Answer 4

Disoriented cells, changes in cell shape/size, development of intracellular damage

Question 5

What are oncogenic viruses?

Answer 5

Viruses that have the ability to cause cancer

Question 6

What are in vitro methods?

Answer 6

Viral cultivation methods that occur in cell or tissue culture

Question 7

What is nucleocapsid?

Answer 7

Term referring to the capsid and nucleic acid together

Question 8

What are spikes?

Answer 8

Projections from the nucleocapsid or envelope that allow viruses to dock with their host cells

Question 9

What is the genome?

Answer 9

The full complement of DNA and RNA carried by a cell

Question 10

What are reverse transcriptases?

Answer 10

Enzymes that synthesize DNA from RNA

Question 11

How were viruses discovered?

Answer 11

By filtering bacteria out of fluid and realizing the fluid was still infectious

Question 12

What are primary cell cultures?

Answer 12

Freshly isolated animal tissue that is cultured to produce a monolayer with the characteristics of the original tissue

Question 13

What are complex capsids?

Answer 13

Capsids found in bacteriophages that form unsymmetrical shapes

Question 14

What is uncoating?

Answer 14

Enzymes in the vacuole dissolve the envelope and capsid, releasing the virus into the cytoplasm

Question 15

What are capsomeres?

Answer 15

Identical protein subunits that spontaneously self-assemble to form the capsid

Question 16

What are viroids?

Answer 16

Viruslike agents that parasitize plants and are composed of naked strands of RNA only

Question 17

What is lysogenic converison?

Answer 17

The acquisition of a new trait from a temperate phage

Question 18

What are bacteriophages?

Answer 18

Viruses that infect bacteria

Question 19

What is the virus envelope?

Answer 19

A modified piece of host cell membrane that is found on some, but not all, viruses

Question 20

What are arenaviruses?

Answer 20

Viruses that pack along host cell ribosomes

Question 21

What genes do viruses possess?

Answer 21

Only those necessary to invade host cells and redirect their activity

Question 22

What is negative-sense RNA?

Answer 22

RNA genomes that need to be converted into the proper form to be made into proteins

Question 23

Why do scientists develop vaccines to viruses as opposed to therapies?

Answer 23

Viruses mutate rapidly, thus making therapy design difficult

Question 24

What are the characteristics of bacteriophage infections?

Answer 24

Infect every known bacterial species, make bacteria more pathogenic to humans

Question 25

What are inclusion bodies caused by viruses?

Answer 25

compact masses of viruses or damaged cell organelles in the nucleus or cytoplasm

Question 26

What is a naked virus?

Answer 26

A virus that consists of only the nucleocapsid

Question 27

What are in vivo methods?

Answer 27

Viral cultivation methods that occur in lab animals or embryonic bird tissues

Question 28

What is a virion?

Answer 28

Fully formed virus capable of establishing infection

Question 29

What are polymerases?

Answer 29

Enzymes that synthesize DNA and RNA

Question 30

What are prophages?

Answer 30

an inactive state in which phage DNA is inserted into the host chromosome

Question 31

What is induction?

Answer 31

Activation of a prophage in a lysogenic cell that leads to a lytic cycle

Question 32

How are enveloped viruses liberated?

Answer 32

Budding or exocytosis

Question 33

Where do DNA viruses replicate?

Answer 33

Nucleus

Question 34

What is positive-sense RNA?

Answer 34

Single-stranded RNA genomes ready for immediate translation into proteins

Question 35

What are satellite viruses?

Answer 35

Viruses that depend on other viruses for replication

Question 36

What constitutes the informal classification system for viruses?

Answer 36

1. Animal, plant, or bacterial virus 2. Enveloped or naked 3. DNA or RNA 4. Helical or Icosahedral

Question 37

What is the host range?

Answer 37

The range of host cell types that a virus can infect

Question 38

What are retroviruses?

Answer 38

Viruses that "borrow" the host's tRNA molecules

Question 39

What is chronic latent state?

Answer 39

Periodic reactivation after a period of viral inactivity

Question 40

What is Interferon?

Answer 40

A naturally occurring human cell product that has shown success in preventing and treating viral infections

Question 41

What happens to a virus during endocytosis?

Answer 41

Entire virus in engulfed by the cell and inclosed in a vesicle or vacuole

Question 42

What is a lytic cycle?

Answer 42

bacteriophage cycle that ends in bacterial cell destruction

Question 43

What are temperate phages?

Answer 43

Bacteriophages that can undergo adsorption and penetration but do not immediately undergo replication and release

Question 44

What are prions?

Answer 44

Distinct protein fibrils found in the brain tissue of animals with encephalopathies

Question 45

What two parts are every virus formed from?

Answer 45

External coating and core containing nucleic acids

Question 46

What are the two main capsid shapes?

Answer 46

Helical and Icosahedral

Question 47

What is a lysogenic cycle?

Answer 47

bacteriophage cycle in which the bacteriophage becomes incorporated into host cell DNA

Question 48

What are replicases?

Answer 48

Enzymes that copy RNA

Question 49

What are cytopathic effects?

Answer 49

Virus-induced damage to the cell that alters its microscopic appearance

Question 50

What are the properties of viruses?

Answer 50

1. Not cells and do not fulfill characteristics of life 2. Obligate intracellular parasites that rely on host cell for reproduction 3. Can have dsDNA, ssDNA, dsRNA, or ssRNA, but not more than one 4. Lack enzymes and protein synthesizing machinery

Question 51

What is adsorption?

Answer 51

The attachment of the virion to the host cell

Question 52

Where do RNA viruses replicate?

Answer 52

Cytoplasm

Question 53

What are the general phases in the "life cycle" of animal viruses?

Answer 53

``` Adsorption Penetration Uncoating Synthesis Assembly Release ```

Question 54

What is a provirus?

Answer 54

Virus whose DNA is incorporated into the DNA of the host

Question 55

What are syncytia?

Answer 55

Fusions of multiple host cells into single large cells containing multiple nuclei

Question 56

What are the purposes of viral cultivation?

Answer 56

Isolation and identification Preparation for vaccines Research

Question 57

What are plaques?

Answer 57

Clear, well-defined patches in the cell sheet caused by radiating patterns of viral infection