Middleton- virus structure, classes

Question 1

_____ are smaller than bacteria, fungus, and other microorganisms

Answer 1

viruses

Question 2

Viruses need what to replicate?

Answer 2

a host

Question 3

T/F: viruses are autopoeitic

Answer 3

false

Question 4

what is the Cellular origin theory of viruses?

Answer 4

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

Question 5

what is the Autopoietic origin theory of viruses?

Answer 5

Proposes that viruses, once autopoietic entities, became dependent on cells for replication.

Question 6

which characteristics are used to classify viruses?

Answer 6

Virus particle structure
Genome
Replication features
Serology
Stability

Question 7

what is a nucleocapsid?

Answer 7

RNA or DNA in a core that is protected by a protein coat (capsid)

Question 8

Nucleocapsid is comprised of repeating protein subunits called _______

Answer 8

capsomeres

Question 9

what are envelopes?

Answer 9

virus-modified cellular membranes acquired upon exit from host

Question 10

what can render an enveloped virus noninfectious?

Answer 10

exposure to lipid solvents in the laboratory

Question 11

the ______ of enveloped viruses may differ between viruses

Answer 11

nucleocapsids

Question 12

what are the different types of single-stranded RNA?

Answer 12

Plus sense ssRNA
minus sense ssRNA
Ambisense

Question 13

name the different structures of viral genomes

Answer 13

Linear
Circular
Segmented
Diploid

Question 14

ssDNA hairpin is an example of what?

Answer 14

replication of viral genome

“rolling hairpin replication”

Question 15

_____ rolling circle replication takes place on circular genomes of viruses

Answer 15

dsDNA

Question 16

The positive strand RNA viruses’ function in same sense as ____

Answer 16

mRNA.

Question 17

Before negative strand RNA can be translated, they must serve as template for what?

Answer 17

an RNA polymerase

Question 18

the mirror image of a negative strand RNA will be the same as what?

Answer 18

positive strand RNA

Question 19

what is the definition of viral attachment?

Answer 19

Binding of a virus receptor to a cellular receptor

Question 20

T/F: viral receptors usually do not mimic cell receptors normal ligands

Answer 20

true

Question 21

the binding of a virus to a cell receptor can cause what?

Answer 21

signaling molecule release
cell adhesion
transport inside the cell

Question 22

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

Answer 22

Attachment

Question 23

____ ____ is a major factor in the eradication of a virus

Answer 23

Host range

Question 24

how does a virus typically enter the host cell?

Answer 24

receptor mediated endocytosis

Question 25

how can non-enveloped virus's can enter the host cell?

Answer 25

through: 1) pores 2) membrane disruptions

Question 26

which protein is responsible for the attachment & fusion of the influenza virus onto the host cell?

Answer 26

HA protein

Question 27

after uncoating in the host cell, what can happen to the viral genome?

Answer 27

Nuclear or cytoplasmic replication

Question 28

describe what happens during nuclear replication

Answer 28

- Genome and remaining protein coat (nucleocapsid) transported to the nuclear membrane - delivery of genome to nucleus

Question 29

describe cytoplasmic replication

Answer 29

- genome released into cytoplasm | - transported to intracellular site of replication

Question 30

___ templates are needed for protein synthesis

Answer 30

RNA (mRNA)

Question 31

DNA viruses rely upon cellular __ _____ to produce RNA templates

Answer 31

RNA polymerases

Question 32

the genome of (+)ssRNA viruses can serve as what?

Answer 32

mRNA

Question 33

(-)ssRNA and dsRNA viruses must bring their own _____ into the cell

Answer 33

polymerase

Question 34

viruses need the cell’s ribosomes to produce what?

Answer 34

proteins

Question 35

T/F: most viruses need a cells ribosomes to produce proteins

Answer 35

False- ALL viruses need them. no exceptions

Question 36

Viral protein production can be regulated at what levels?

Answer 36

transcription (mRNA) level translation level

Question 37

_____ proteins are produced in high quantities during viral translation

Answer 37

structural

Question 38

with (+)ssRNA viruses, the ______ serves as a template for translation

Answer 38

the genome

Question 39

_______ is needed in (-)ssRNA viruses to copy the template for a new genome

Answer 39

Polymerase

Question 40

when (-)ssRNA and dsRNA replicate, the Virus particle must include what?

Answer 40

the viral polymerase

Question 41

what is the role of Polymerase?

Answer 41

makes messenger RNA for translation

Question 42

dsRNA induces what so that the genome stays inside the particle?

Answer 42

innate immune response

Question 43

the mRNA serves what function during dsRNA replication?

Answer 43

serves as (+) strand in virus genome the (-) strand synthesized during assembly

Question 44

both ssDNA and dsDNA must gain access to the ____ for replication

Answer 44

the nucleus

Question 45

what proteins aid in assembly of the virus?

Answer 45

localize structural proteins

Question 46

during assembly, the genome contains what?

Answer 46

packaging signals

Question 47

how are adenoviruses assembled?

Answer 47

the empty protein coat imports the genome

Question 48

how are Reoviruses assembled?

Answer 48

RNA packaged during capsized assembly

Question 49

how is a retrovirus assembled?

Answer 49

pre-assembly on a membrane

Question 50

what are the 2 ways viruses are released from a host cell?

Answer 50

Lysis | Budding

Question 51

name the 3 phases of virus replication

Answer 51

1) eclipse 2) exponential growth 3) plateau

Question 52

what is meant by the "time for one step growth"?

Answer 52

the length of time between start of infection and beginning of plateau phase

Question 53

Fluorescent focus assays use a stain with a labeled ______

Answer 53

antibody

Question 54

plaque assay's use a cell monolayer, which when infected leads to what?

Answer 54

the death of cells and the formation of cleared areas (plaques)

Question 55

infectious dose assays use what type of systems?

Answer 55

tissue cultures, eggs, animals

Question 56

what are the 2 particle assays?

Answer 56

A) electron microscopy B) hemagglutinin assay

Question 57

viruses bind to red blood cells in which assay?

Answer 57

hemagglutinin assay

Question 58

name the 2 genome assays

Answer 58

A) PCR- polymerase chain reaction B) southern (DNA) & northern (RNA) blots

Question 59

name the serological assays

Answer 59

1) virus neutralization 2) enzyme link immunosorbant (ELISA) 3) western (protein) blot