Virus Classification

Question 1

how is a virus different from a bacterium

Answer 1

Virus can NOT replicate w/out a host

-bacteria replicate autonomously

Question 2

how is a virus different from a toxin

Answer 2

Virus CAN replicate inside a host

-toxin can not replicate

Question 3

what is a bacteriophage

Answer 3

it is a virus that attacks then replicates inside a bacteria

Question 4

T/F Bacteria are smaller than viruses ?

Answer 4

F - virus are smaller from 18-300 um

Question 5

What are the two theories of Virus Origin

Answer 5

• Cellular origin - viruses were once cellular components and evolved separate over time
• Autopoietic Origin - viruses were originally their own independent entities and evolved to become dependent on other cells for replication

Question 6

What are the 5 ways to classify a virus

Answer 6

• virus particle structure (main)
• genome (main)
• replication features (main)
• serology
• stability

Question 7

using virus particle structure to classify a virus takes into account what 3 characteristics

Answer 7

• composition
• size
• shape

Question 8

what is a nucleocapsid

Answer 8

RNA or DNA core protected by a capsid

Question 9

what is a capsid

Answer 9

a virus’ protein coat

Question 10

a virus is defined by its ______ structure

Answer 10

nucleoplasmid

Question 11

nucleocapsids are composed of individual repeating protein subunits called ?

Answer 11

capsomeres

Question 12

A virus particle structure may have envelopes, what are they ?

Answer 12

its a virus-modified cellular membrane

Question 13

what are some disadvantages of an envelope

Answer 13

very susceptible to many lab solvents

Question 14

what are the different types of genomes that a virus can have that help to classify viruses

Answer 14

DNA - single or double
RNA - single or double
—-(+) sense ssRNA
—–(-) sense ssRNA

Question 15

what is the difference b/w (+) sense ssRNA and (-)sense ssRNA

Answer 15

(+)sense ssPNA is ready to be used to make proteins whereas (-)sense ssRNA must transcribe first

Question 16

in order for replication to start in ssDNA, what specific structure must be formed

Answer 16

ssDNA hairpin

Question 17

in order for replication of dsDNA to start, what structure must be formed

Answer 17

dsDNA rolling circle

Question 18

in order for a RNA virus to start replication, what does it require that a DNA virus does not

Answer 18

RNA dependent RNA polymerase

Question 19

what type of viral genome needs access to the nucleus to start replication

Answer 19

DNA virus

Question 20

what type of viral genome requires a RNA dependent RNA polymerase in order to start replication

Answer 20

RNA virus

Question 21

what is the major factor of eradication of a virus

Answer 21

host range (tropism)

• easier to eradicate if only infect human hosts
• hard to eradicate if host range is all mammals

Question 22

what is the major determinent of a virus’ host range (tropism)

Answer 22

attachment

Question 23

which needs an RNA dependent RNA polymerase in order to start replication,
(+) sense ssRNA or (-) sense ssRNA

Answer 23

(-)sense ssRNA

Question 24

all virus/ rely on what host organelle to produce their own viral proteins ?

Answer 24

ribosomes cuz virus have NONE

Question 25

What are the 3 ways of release after replication that help classify viruses

Answer 25

• Lysis
• weak lysis
• Budding

Question 26

what specific type of viruses are released via budding

Answer 26

enveloped viruses

Question 27

when examining the replication kinetics of viruses, what type of growth curves are used

Answer 27

one step growth curves

Question 28

T/F viruses are obligate intracellular parasites

Answer 28

T

Question 29

when are virus’ considered “alive”

Answer 29

when they are inside the cells