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Flashcards in Chapter 13 Deck (53):
1

Host Specificity

Host Range Speficificity- the variety of host cells a virus may infect
host specific- usually infects only a single species of host.
tissue specific- usually infects only a certain tissue type.

2

Isocahedral

cubic shape.
polyherdal
determined by EM and X-Ray crystallography

3

influenzae

A virus that is found in a numer of different animals and can be transmitted to other species including humans. If not treated properly the virus can become very serious.

4

interferons

A specific group of cytokines. Alpha- and Beta-- IFNs are antiviral proteins produced by certain animal cells in response to a viral infection.
Gamma- IFN stimulates macrophage activity.

5

Late Products

Capsomers
Lysins(cause host cell to lyse)

6

Latent Virus Protection

Vaccine

7

Ligand

part of a virus that allows the virus to attach to receptors on the host cell.

8

Lysogenic Conversion

Involves toxin production
gives bacteria new characteristics
diptheria

9

lysogenic cycle

The virus intigrates into the host genome- host dna

1. lysogenic or termperature phages undergo lysogeny to for a prophage
2. induction of a lytic infection
3. latent or slow viral infections
4. lysogenic conversion
5. oncogenic viruses

10

lysogenic phage

undergo lysogeny to form a prophase

11

What are Antiviral Protiens (AVP)? What do they accomplish in a cell?

Involved in the defense against viruses. Interferon production stimulates the production of AVP in adjascent cells. AVP shuts down the cells metabolism, and cell dies.

12

What are the ways of attachment for a virus?

Ligand receptors and spike proteins.

13

What are Bacteriophages?

Part of the culturing viruses.

14

What is Biosynthesis?

Stage during the Lytic cycle. It is the synthesis of viral products. There is an eclipse period which is the best time to kill the cell.

15

What is Budding?

when newly formed viruses push through the cell membrane.

16

What is a Burst Size? What is the most dangerous burst size?

Release stage of the Lytic cycle. The number of new viruses released. A large burst size in a short burst time is most dangerous.

17

What is Burst Time? What is the most dangerous burst time?

Release stage of the Lytic cycle. Attachment until lysis. Short burst time with large burst size is most dangerous.

18

What is a Capsid?

Protein coat. Made up of repeating protein units called capsomers.

19

What is a Capsomere?

Repeating protein units that make up the capsid.

20

Lytic cycle

Results in lysis of the host cell; includes five stages: attachment, penetration, biosynthesis, maturation, and release.

21

Maturation

assembly of new viruses or virions; combining of capsids and viral nucleic acids

22

Penetration

contents of the Capsid enter the host cell by injection, fusion, or endocytosis.

23

Release

The host cell ruptures releasing the newly formed viruses or the newly formed viruses push through the cell membrane (budding)

24

Obligate intracellular parasites

these require a host cell to replicate.

25

Polyhedral virus

polyhedral means many-sided; most polyhedral viruses are in the shape icosahedral

26

Primary cell lines

derived from tissue slices; tend to die out after only a few generations.

27

Oncogenic virus

cancer causing viruses

28

Complex viruses

bacteriophages and poxviruses (very intricate)

29

Continuous Cell Lines

A part of tissue cultures involving animal viruses. These cell lines will grow indefinately and cause cancer.

30

CPE

Cyto-Pathic Effects. Tissue cultures look for these effects.

31

Early Products

Enzymes or tools

32

Eclipse period

"The best time to kill the cell". No viable virus inside the cell. (Attachment, Penetration, and Biosynthesis)

33

Embryonated eggs

(Fertilized). Culturing viruses in eggs can weaken the virus.

34

Endocytosis

most common form of penetration

35

Envelope

Lipids of host cell origin. May contain spikes for attachment, hemagglutination (not all viruses have envelopes)

36

Helical viruses

Long rods (elongated). Length depends on the size of the genome

37

HIV

Carries reverse transciptase. (RNA virus). Slow viral infection

38

In which of the following ways do virus differ from bacteria?
A) Viruses are filterable.
B) Viruses are obligate intracellular parasites.
C) Viruses don't have any nucleic acid.
D) Viruses are not composed of cells.
E) Viruses don't reproduce.

D) Viruses are not composed of cells.

39

Which of the following statements about spikes is false?
A) They are used for penetration.
B) They are used for attachment.
C) They are found only on enveloped viruses.
D) Antibodies against spike proteins may block virus attachment.

A) They are used for penetration.

40

Which of the following is NOT used as a criterion to classify viruses?
A) Biochemical tests
B) Morphology
C) Nucleic acid
D) Size
E) Number of capsomeres

A) Biochemical tests

41

Which of the following is NOT a method of
culturing viruses?
A) In laboratory animals
B) In culture media
C) In embryonated eggs
D) In cell culture
E) None of the above

B) In culture media

42

Bacteriophages and animal viruses do NOT differ significantly in which one of the following steps?
A) Adsorption
B) Penetration
C) Uncoating
D) Biosynthesis
E) Release

D) Biosynthesis

43

The definition of lysogeny is …
A) Phage DNA is incorporated into host cell DNA.
B) Lysis of the host cell due to a phage.
C) The period during replication when virions are not present.
D) When the burst time takes an unusually long time.
E) Attachment of a phage to a cell.

A) Phage DNA is incorporated into host cell DNA.

44

A clear area against a confluent "lawn" of bacteria is called a
A) Phage.
B) Pock.
C) Cell lysis.
D) Plaque.
E) Rash.

D) Plaque.

45

Continuous cell lines differ from primary cell lines in that
A) Viruses can be grown in continuous cell lines.
B) Continuous cell lines always have to be reisolated from animal tissues.
C) Continuous cell lines are derived from primary cell lines.
D) Continuous cell lines can be maintained through an indefinite number of generations.
E) Continuous cell lines are from human embryos.

D) Continuous cell lines can be maintained through an indefinite number of generations

46

Lysogeny can result in all of the following EXCEPT
A) Immunity to reinfection by the same phage.
B) Acquisition of new characteristics by the host cell.
C) Immunity to reinfection by any phage.
D) Transduction of specific genes.
E) None of the above.

C) Immunity to reinfection by any phage.

47

Some viruses, such as human herpes virus 1, infect a cell without causing symptoms; these are called
A) Latent viruses.
B) Lytic viruses.
C) Phages.
D) Slow viruses.
E) Unconventional viruses.

A) Latent viruses.

48

An envelope is acquired during which of the following steps?
A) Penetration
B) Adsorption
C) Un-coating
D) Biosynthesis
E) Release

E) Release

49

An example of a latent viral infection is
A) Subacute sclerosing panencephalitis.
B) Cold sores.
C) Influenza.
D) Smallpox.
E) Mumps.

B) Cold sores.

50

Put the following in the correct order for DNA-virus replication:
1-Maturation; 2-DNA synthesis; 3-Transcription; 4-Translation.
A) 1, 2, 3, 4
B) 2, 3, 4, 1
C) 3, 4, 1, 2
D) 4, 1, 2, 3
E) 4, 3, 2, 1

B) 2, 3, 4, 1

51

A viral species is a group of viruses that …
A) Have the same morphology and nucleic acid.
B) Have the same genetic information and ecological niche.
C) Infect the same cells and cause the same disease.
D) Can't be defined.

B) Have the same genetic information and ecological niche.

52

Which of the following is most likely a product of an early gene?
A) Capsid proteins
B) DNA polymerase
C) Envelope proteins
D) Spike proteins
E) Lysozyme

B) DNA polymerase

53

A.M.
RNA viruses carry which of the following enzymes?
A) DNA-dependent DNA polymerase
B) RNA-dependent RNA polymerase
C) Reverse transcriptase
D) ATP synthase

Answer: C, actually B is also correct. RNA viruses cannot use host cell enzymes to replicate their nucleic acids and must carry their own enzymes.