MicroBio Q's TF CH 5 Flashcards Preview

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Flashcards in MicroBio Q's TF CH 5 Deck (64):
1

The genetic material found in a virion is usually what?

Either DNA or RNA

2

Viral particles are composed of what?

DNA or RNA, a coat of protein, and layers of carbohydrates, lipids and additional proteins

3

What is the best microscopic methods for studying viruses?

Electron microscopy

4

What is the function of the viral capsid?

To the protect the viral genome

5

The Tobacco mosaic virus exhibits which type of capsid symmetry?

Helical

6

An example of a virus that exhibits binal symmetry is known as what?

Bacteriophages

7

Viral spikes or peplomers are involved in what?

Attachment

8

Which structures are associated with the influenza virus?

Neuraminidase enzyme, hemagglutinin protein, and glycoproteins

9

The most common viral nucleic acid types are what?

dsDNA and ssRNA

10

What is the first step in the generalized viral life cycle?

Attachment of virus to host cell

11

What is viral host specificity most likely attributed to?

Interaction between receptors on the surface of the host cell and ligands on the surface of virions

12

Which mechanisms do eukaryotic viruses enter host cells through?

Through fusion of the viral envelope with the host cell membrane, entry by endocytosis, and injection of nucleic acid

13

Which types of viruses must carry their own replication enzymes in their nucleocapsid?

RNA viruses only

14

Where does the energy that is required for bacteriophage assembly come from?

Host metabolic activity

15

What is a common virion release method observed in enveloped viruses?

Budding

16

What is the name of the relationship with the host cell in which the virus remains within the host without destroying it called?

Lysogeny

17

What does an advantage of lysogeny to the host include?

Resistance to superinfection

18

When more phage are present in the environment than there are host cells, which type of host relationship is most desirable?

Lysogenic preferred

19

What are microscopic and/or macroscopic damages to host cells caused by eukaryotic viruses called?

Cytopathic effects

20

What is the name for a type of viral infection in which there is a low release of virions without cell death?

Chronic infection

21

What cellular genes required for normal growth, but when mutated or overexposed, cause carcinogenesis?

Proto-oncogenes

22

Which of the following viruses is NOT definitely linked to causing cancer in humans?

Rabies virus

23

Which methods can be used to cultivate plant viruses?

Grow in cultures of plant cells lacking cell walls, mechanically break leaves to expose cells to infection, or graft diseased part onto a healthy plant

24

What can be used to determine direct counts of viral particles?

Epifluorescence microscopy

25

What is an indirect method of counting animal viruses?

Hemagglutination assay

26

The number of plaque-forming units (PFUs) is calculated from a viral plaque assay by.....?

Multiplying the number of plaques per volume by the dilution

27

What is teh dilution taht contains the number of viral cells large enough to destroy 50% of the host cells or organisms called?

The lethal dose

28

What are infectious RNAs that primarily infect plants called?

Viroids

29

What are infectious proteins responsible for bovine spongiform encephalopathy called?

Prions

30

Viruses are considered to be living organisms

FALSE

31

Scientists classify viruses based on genome structure, life cycles, morphology, and genetic relatedness

TRUE

32

Most viruses are approximately the same size as bacteria (0.2 to 2 micrometers)

FALSE

33

Hos-independent growth has never been observed in either the bacterial or archaeal viruses

FALSE

34

The size of a helical capsid is influenced by both its protomores and the nucleic acids enclosed within the capsid

TRUE

35

The icosohedral capsid maximizes efficiency and requires few genes for its coding

TRUE

36

An envelope is present in all viruses

FALSE

37

Spikes can be used to identify many types of viruses

TRUE

38

All virions lack enzymes

FALSE

39

Most DNA viruses use dsDNA as their genetic material

TRUE

40

Many RNA viruses have segmented genomes with each segment coding for a protein

TRUE

41

Viral attachment to the host cell is a random process

FALSE

42

Variation in receptors used by a virus for attachment is partly responsible for host specificity

TRUE

43

All viruses inject their nucleic acid into the cytoplasm of their host, leaving the capsid outside and attached to the cell wall

FALSE

44

Human immunodeficiency virus (HIV) enters the host cell by fusing directly with the host cell plasma membrane

TRUE

45

DNA and RNA viruses replicate using the same processes

FALSE

46

Bacteriophages are assembled in the host cytoplasm

TRUE

47

All animal viruses are assembled in the cytoplasm

FALSE

48

Many nonenveloped viruses lyse their host cells at the end of the intracellular phase

TRUE

49

When viral cells are released via budding, the host cell may survive and continue releasing virions for some time

TRUE

50

Actin filaments in the cytoskeleton can aid in the release of eukaryotic viruses

TRUE

51

Temperate phages must release from the host cell via lysis

FALSE

52

Temperate phages can integrate their genome with the host genome

TRUE

53

Host cells that are infected with a temperate virus cannot be infected by other virions of the same type

TRUE

54

temperate phages can alternate between lysogenic and lytic stages

TRUE

55

Lysogeny enables survival of host cells in an environment with low multiplicity of infection (MOI)

FALSE

56

A chronic infection is a situation in which a virus slowly releases virions without killing the cell

TRUE

57

Most human viruses associated with cancer have dsDNA genomes

TRUE

58

Some strains of human papillomavirus (HPV) can cause cervical caner

TRUE

59

Tumor activator proteins promote formation of tumors in human dsDNA viruses

FALSE

60

Viruses are easily cultivate in agars and broths, much like bacteria

FALSE

61

Plaque assays determine viral numbers based on infectivity of the virus

TRUE

62

The number of plaque-forming units (PFUs) is equal to the number of viruses because all virions are infective

FALSE

63

The infectious dose (ID60) of a virus is the dose that, when given to a number of hosts, causes and infection of 50% of the hosts under particular conditions

TRUE

64

Viroids, or infectious RNAs, cause many important plant diseases

TRUE