Virology

Question 1

what is a virus

Answer 1

genetic element that can replicate only inside a living cell

Question 2

what do viruses rely on the host cell for

Answer 2

energy , metabolic intermediates, and protein synthesis

Question 3

what is the extracellular form of a virus

Answer 3

virion

Question 4

a virus cannot replicate until it has done what

Answer 4

infect a host cell

Question 5

how large are viruses

Answer 5

20-300nm

Question 6

how many base pairs do viruses have

Answer 6

less than 700kbp

Question 7

what is essential to the survival of a virion

Answer 7

the capsid

Question 8

what is a capsid

Answer 8

a protein sheath containing the virus genome

Question 9

what types of host does a virus use if it doesnt have a capsid

Answer 9

probably bacterial

Question 10

if a virus has a capsid, what will it most likely use as its host

Answer 10

animal

Question 11

what is it called when a virus has no envelope

Answer 11

naked

Question 12

what is the envelope of a virus made of

Answer 12

protein plus lipid

Question 13

what is the purpose of the virion

Answer 13

to protect the virus when it is outside of a host cell

Question 14

what is a nucleocapsid

Answer 14

inner structure of nucleic acid plus the capsid protein (the whole thing)

Question 15

what are the two ways a virus can infect the host

Answer 15

lytic or lysogenic

Question 16

what is lytic infection

Answer 16

virus redirects hosts metabolism to support virus replication (host cell destroyed)

Question 17

what is lysogenic infection

Answer 17

host cell is not destroyed but is genetically altered and the virus genome becomes part of the host genome

Question 18

what is the protein that a capsid is made up of

Answer 18

capsomers

Question 19

what is the nucleic acid for viruses

Answer 19

DNA OR RNA

Question 20

how are virus nucleic acids further divided

Answer 20

single or double stranded, plus sense or minus sense

Question 21

what is the shape of viral genomes

Answer 21

circular or linear

Question 22

what is viral plus sense RNA synonymous to

Answer 22

exact same base pairing as viral mRNA

Question 23

what is viral minus sense RNA

Answer 23

complimentary base pairing to viral mRNA

Question 24

what types of viruses typically have the smallest genomes

Answer 24

RNA have smaller genome than DNA

Question 25

what is another name for bacterial viruses

Answer 25

bacteriophages

Question 26

virion assembly being a spontaneous process what is it called

Answer 26

self assembly

Question 27

what are the two primary shapes for a virus

Answer 27

rod or spherical

Question 28

what kind of symmetry do rod shaped bacteria have

Answer 28

helical

Question 29

what kind of symmetry do spherical viruses have

Answer 29

icosahedral symmetry

Question 30

where does a non-enveloped virus get its envelope from

Answer 30

it gets it from the host cell upon infection (takes host cell membrane)

Question 31

how many faces does an icosahedron have

Answer 31

20 triangular faces and 12 vertices

Question 32

axes of symmetry divide an icosahedron into how many segments

Answer 32

5, 3, or 2

Question 33

is an icosahedron or a rod preferable to a virus

Answer 33

icosahedron is preferred because it takes less capsomers to make

Question 34

what is the most complex viral shape

Answer 34

head-plus-tail

Question 35

most enveloped viruses affect what

Answer 35

animals

Question 36

why do you not find enveloped viruses in bacteria and plants

Answer 36

because they have cell walls and these are much more difficult tp penetrate

Question 37

why are envelopes so important to viruses

Answer 37

its what comes into contact with animal cells and the two membranes must fuse before penetration

Question 38

what on the virus envelope allows for attachment to the host cell

Answer 38

there are embedded proteins in the virus envelope (often glycoproteins)

Question 39

what do naked viruses use to attach to the host cell

Answer 39

peplomers

Question 40

what must a virus do first in order to replicate itself

Answer 40

it must take infect a host cell

Question 41

why can a virus not use a dead host cell in order to replicate

Answer 41

there are energy requirements so it needs a living cell to get energy from

Question 42

what are the 5 steps of viral replication

Answer 42

attachment, penetration, synthesis, assembly, release

Question 43

what happens in attachment of a viral cell

Answer 43

virus attaches to host

Question 44

what happens in penetration of a virus

Answer 44

enters host cell and injects its genome

Question 45

what happens in synthesis of a virus

Answer 45

makes new genetic material using the host cell energy and nutrients

Question 46

what happens in assembly of a virus

Answer 46

package genomes into new individual viruses

Question 47

what happens in the release of viruses

Answer 47

viruses are released from the host cell (lysis)

Question 48

what are the ways virions can be released from a cell

Answer 48

lysis, budding, excretion

Question 49

when we treat viral infections what are we trying to do

Answer 49

trying to use antibodies to block attachment of virus to host cells

Question 50

what are two ways that a virus can resist the defenses of the host

Answer 50

restriction endonucleases | nucleic acid modifications

Question 51

what is a temperatre virus

Answer 51

double stranded DNA virus that can infect host long term in a stable relationship

Question 52

what nucleic acid does class 3 viruses have

Answer 52

double stranded RNA

Question 53

what nucleic acid does class 4 viruses have

Answer 53

single strranded positive RNA

Question 54

what nucleic acid does class 5 viruses have

Answer 54

single stranded negative RNA

Question 55

what nucleic acid does class 6 viruses have

Answer 55

single stranded positive RNA

Question 56

what nucleic acid does coronaviruses have

Answer 56

ssRNA (+)

Question 57

what nucleic acid does the polio virus have

Answer 57

ssRNA(+)

Question 58

what kinda of viruses have ssRNA(-)

Answer 58

rhabdoviruses, orthmyxovirus, paramyxovirus

Question 59

how are viruses identified for immunizations

Answer 59

H_N_

Question 60

what does H refer to

Answer 60

hemagluttinin

Question 61

what does N refer to

Answer 61

Neuraminidase

Question 62

what kind of nucleic acid does class 1 and 7 viruses have

Answer 62

dsDNA

Question 63

what kind of nucleic acid does class 2 viruses have

Answer 63

ssDNA(+)

Question 64

what class of viruses uses reverse transcriptase

Answer 64

class 6 viruses

Question 65

what is reverse transcription

Answer 65

process of copying RNA into DNA

Question 66

what is the phenomena of overlapping genes

Answer 66

insufficient DNA to encode all viral-specific proteins unless parts of the genome are read multiple times in different reading frames

Question 67

why is hemagluttinin so important in immunizations

Answer 67

hemmaglutinin is highly immunogenic

Question 68

what is the function of neuraminidase

Answer 68

breaks down sialic acid in host cytoplasmic membrane

Question 69

why does antigenic shift occur

Answer 69

RNA makes mistakes and cannt go back and fix them like DNA can

Question 70

why does antigenic drift happen

Answer 70

more so mutations to the virus over time (much slower than shift)

Question 71

what are the two sub viral particles

Answer 71

viroids and prions

Question 72

what do viroids typically infect

Answer 72

plants

Question 73

what are viroids most importantly missing

Answer 73

proteins

Question 74

what do prions infect

Answer 74

only animals

Question 75

what important thing are prions lacking

Answer 75

no nucleic acid

Question 76

what do prions transmit

Answer 76

spongiophore enecephalopathies (mad cow disease, scrapie)

Question 77

how do prions do their damage

Answer 77

cause proteins in host cells to fold incorrectly, losing their function