Viruses

Question 1

What type of ecosystems do viruses play a role in?

Answer 1

marine ecosystem

Question 2

What is a virus?

Answer 2

a noncellular particle that must infect a host cell to reproduce

Question 3

What does a virion consist of?

Answer 3

nucleic acid (DNA or RNA) contained within a protective protein coat called the capsid

Question 4

host range

Answer 4

a particular group of species that a virus infects

Question 5

Viruses take over the infected cell’s ________ and direct the cell to ______ more virus particles.

Answer 5

machinery; produce

Question 6

Average size of a virus

Answer 6

50-100 nm

Question 7

What are giant viruses called?

Answer 7

pandora viruses

Question 8

Three things that virus nucleic acid can be:

Answer 8

1. DNA/RNA
2. linear or circular
3. ds or ss

Question 9

Name a few genes that the virus genome can encode for

Answer 9

capsomere, envelope protein, polymerase

Question 10

Capsid

Answer 10

protein coat made of repeating protein subunits called the capsomere; used for protection and packaging of the viral genome

Question 11

envelope

Answer 11

lipid bilayer that surrounds the capsid and obtained from the host cell membrane (budding)

Question 12

Enveloped viruses are ____ sensitive to inactivation by ____ or ______________ than nonenveloped viruses.

Answer 12

more; heat; detergents

Question 13

Spikes

Answer 13

glycoproteins in the envelope

Question 14

What do spikes help with?

Answer 14

Attachement to/release from the host cell

Question 15

Four Virus Shapes

Answer 15

1. Filamentous/Helical
2. Icosahedral
3. Complex
4. Other

Question 16

3 characteristics of helical viruses

Answer 16

1. vary in length, depending on genome size
2. helical symmetry
3. include bacteriophages as well as animal viruses

Question 17

Are viruses included in the binomial nomenclature scheme?

Answer 17

no

Question 18

3 things classification is based on

Answer 18

1. nucleic acid
2. morphology
3. method of replication

Question 19

viral species

Answer 19

group of viruses that share the same genetic information and host range

Question 20

family names end in

Answer 20

-viridae

Question 21

genus names end is

Answer 21

-virus

Question 22

What type of names are used for species?

Answer 22

common

Question 23

How are subspecies designated?

Answer 23

by numbers

Question 24

3 identification methods

Answer 24

1. cytopathic
2. sereological
3. nucleic acid sequence

Question 25

2 life cycles for bacteriophage

Answer 25

lystic, and lysogenic

Question 26

3 life cycles of animal viruses

Answer 26

DNA, RNA, retrovirus

Question 27

5 steps of lytic cycle

Answer 27

Attachment, Penetration, Biosynthesis, Assembly/maturation, Release

Question 28

5 steps of lysogenic cycle

Answer 28

attachment, penetration, integration, excision, lytic cycle

Question 29

6 steps of general life cycle of animal viruses

Answer 29

attachment, penetration, uncoating, biosynthesis, maturation, release

Question 30

release of enveloped viruses from infected cells

Answer 30

budding

Question 31

release of nonenveloped viruses from infected cells

Answer 31

lysis, exocytosis

Question 32

RNA viruses

Answer 32

use an RNA dependent RNA polymerase to transcribe their RNA

Question 33

DNA virus

Answer 33

uses the host replication machinery

Question 34

retrovirus

Answer 34

uses reverse transcriptase to copy their genomic sequence into DNA for insertion into the host chromosome

Question 35

Is influenze A enveloped or nonenveloped?

Answer 35

enveloped

Question 36

H

Answer 36

hemagglutinin protein; 16 subtypes; attachment to host cell;

Question 37

N

Answer 37

neuraminidase; 9 subunits; involved in release from host cell

Question 38

Antigenic Drift

Answer 38

gradual change in surface molecules of virus (spikes)

Question 39

Why is antigenic drift bad?

Answer 39

host antibodies may not recognize the altered antigens

Question 40

acute infection

Answer 40

rapid production of virus particles, relatively brief period of disease symptoms, the host immune response rids body of infecting virus

Question 41

Viroids

Answer 41

Rna molecules that infect plants; NO protein capsid

Question 42

Are viruses bigger than viroids?

Answer 42

YES

Question 43

How do viroids replicate?

Answer 43

by host RNA polymerase; weird because it usually requires a DNA template

Question 44

some viroids have _______ ability

Answer 44

catalytic

Question 45

Prions

Answer 45

proteins that infect animals with no nucleic acid component

Question 46

Where do prions come from?

Answer 46

derived from normal cellular proteins

Question 47

What do prions do?

Answer 47

alter the conformation of normal cellular proteins

Question 48

How do you get prions? (4)

Answer 48

1. inherited 2. transmissible through: ingestion 3. transplant 4. surgical instruments

Question 49

4 diseases prions can cause:

Answer 49

1. Sheep scrapie, 2. Mad Cow Disease 3. Chronic wasting Disease 4. Spongiform encephalopathies

Question 50

What causes Creutzfeldt-Jakob disease?

Answer 50

prions

Question 51

What are the symptoms of Creutzfeldt-Jakob disease?

Answer 51

dementia, blindness, impaired muscular coordination, behavioral changes (insomnia, depression)