Final; Virus Biology Flashcards Preview

SP14 Microbiology > Final; Virus Biology > Flashcards

Flashcards in Final; Virus Biology Deck (62):
1

What are the two theories of virus origin

cellular origin
autopoietic origin

2

This proposes that viruses were once cellular components but over time they evolved separately

cellular origin

3

This proposes that viruses, once autopoietic entities, became dependent on cells for replication

autopoietic origin

4

What are the attributes that viruses are classified on

particle structure
genome
replication features
serology
stability

5

What are the components of virus particle structure

composition
stucture
size

6

This is RNA or DNA in a core that is protected by a protein coat

nucleocapsid

7

A virus is defined by what

the nucleocapsid structure

8

What are the different nucleocapsid structures

helical
pleomorphic
icosahedral

9

A nucleocapsid is comprised of what

repeating protein subunits called capsomeres

10

This is a virus-modified cellular membrane acquired upon exit from the host

envelopes

11

This renders enveloped viruses noninfectious

exposure to lipid solvents in the laboratory

12

True or False
Enveloped viruses may have nucleocapsids with different structures

True

13

What are the lengths of the smallest and largest virus particle

smallest; 18nm
largest; 300nm

14

What are the different combinations of the viral genome

double or single stranded
DNA or RNA

15

What different types of single stranded RNA can you have

plus sense ssRNA
minus sense ssRNA
ambisense

16

Which type of ssRNA can be used directly for translation

plus sense

17

What must happen to minus sense ssRNA before translation

a positive (plus sense) copy must be made

18

What are the different structures (gene arrangement) of the viral genome

linear
circular
segmented
diploid

19

How can viruses not follow the central dogma

They are able to revert from RNA to DNA via reverse transcriptase

20

What do most DNA viruses need that RNA viruses do not

access to the nucleus

21

What do RNA viruses need that DNA viruses do not

the ability to make positive/negative strands
reverse transcriptase

22

What is the process of viral replication

attachment
entry
transcription
translation
replication
assembly
release

23

How does a virus attach to a cell

via receptors
the cell does not have viral receptors, the virus binds to already functional receptors on the cell

24

What type of cell receptors do viruses bind to

signaling
cell adhesion
transport

25

How to viruses attach to the cell receptors

do not mimic cell receptor ligands
typically spike like projections
may require co-receptor

26

This is a major determinant of virus tropism (host range)

attachment

27

True or False
Viruses are only specific to humans

False; viruses are known to infect essentially all forms of life

28

This is a major factor in eradication

host range

29

What are the pathways of viral entry

receptor mediated endocytosis
direct penetration of plasma membrane

30

How can non-enveloped viruses entry the cell

its not well understood
perhaps through pores or membrane disruption

31

In what ways can enveloped viruses enter the cell

membrane fusion
receptor conformational change (pH; receptor induced)

32

How does nuclear replication occur

the genome and remaining protein coat are transported to the nucleus to deliver the genome

33

How does cytoplasmic replication occur

genome is released into cytoplasm to site of replication
many RNA viruses replicate in MACs

34

dsRNA viruses never release what

their genomic material from the entering particle

35

DNA viruses rely on what for transcription

cellular RNA polymerases

36

The genome of what can serve was mRNA

+ssRNA

37

These RNA viruses must bring their own polymerases into the cell

-ssRNA
dsRNA

38

All viruses need what to produce proteins

the cells ribosomes

39

Non-structural proteins are only seen where

inside the infected cell

40

The order of genomic replication of viruses depends on what

virus genome

41

This induces innate immune response so the genome stays inside the particle

dsRNA

42

The dsRNA mRNA is synthesized where

inside the particle and is then transported to the cytoplasm

43

Why are poxviruses an exception to the DNA viruses needing access to the nucleus

virion contains the necessary RNA polymerase and the genome encodes the DNA polymerase for replication

44

What is the function of viral assembly

to package new genomes into functional particles

45

What aids in assembly

localized structural proteins; cellular viral "factories"
the genome contains packaging signals

46

How does an adenovirus undergo assembly

empty protein coat imports genome

47

How does a reovirus undergo assembly

RNA packaged during capsid assembly

48

How does a retrovirus undergo assembly

reassembly on a membrane

49

What are the different types of viral releases

lysis
weak lysis (impair membrane repair)
budding (enveloped only)

50

What are the kinetic phases of viral replication

eclipse; attachment and uptake
exponential growth; replication and assembly
plateau; cell death

51

True or False
There is a variety of the length of time it takes for a virus to go from the start on an infection to the beginning of a plateau

True;
bacteriophage; 30 mins
vaccina; 24 hours

52

What is the productivity of a virus

measure amplification
vesicular stomatitis virus (VSV) 1:1000
vaccina 1:100

53

What methods are used to initially discover a virus

disease in host
contaminant in cell culture

54

What methods are used to confirm a virus

purification
confirmation of disease; animals, eggs, or cell culture (preferred)

55

What are the principle of detection and quantification methods

infectivity
physical
genome
serological

56

These methods are useful for viruses that cannot be cultivated

molecular methods

57

What are four types of infection assays

cytopathic effect (CPE)
fluorescent focus assay
plaque assay
Infectious dose

58

What are two types of particle assays

electron microscopy
hemagglutinin assau

59

What are two types of genome assays

PCR
southern (DNA) and northern (RNA) blots

60

What are three types of serological assays

virus neutralization
enzyme linked immunosorbant assay (ELISA)
western (protein) blot

61

True or False
Different methods of viral detection and quantification give different answers

True

62

What is the average diameter of a human virus

30-300nm