Chapter 5 - viruses

Question 1

Viruses are _____________ ________ _________ (meaning they cannot function outside of a host cell).

Answer 1

intracellular obligate parasites

Question 2

Viruses are typically between __ and ___ nanometers.

Answer 2

10 and 100

Question 3

Virus genomes are typically between a few thousand to ______ nucleotides in length.

Answer 3

200,000

Question 4

Viruses may contain ______ OR _______-stranded DNA or RNA.

Answer 4

single or double

Question 5

The protein shell around a genome is called a ______.

Answer 5

capsid

Question 6

Capsids are composed of many __________ proteins.

Answer 6

capsomere

Question 7

When a capsid and genome are together, the structure is called a ____________.

Answer 7

nucleocapsid

Question 8

Viruses could possibly have an ________ (plasma membrane taken from a host cell around the capsid).

Answer 8

envelope

Question 9

Capsids often exhibit either _______ or ___________ (sometimes called polyhedral) shapes.

Answer 9

helical, icosahedral

Question 10

If a plasma membrane surrounds the nucleocapsid, the virus is “_________.”

Answer 10

enveloped

Question 11

If there is no plasma membrane, the virus is “_____.”

Answer 11

naked

Question 12

Enveloped viruses are mostly associated with _______ (including ______) as their hosts.

Answer 12

animals, humans

Question 13

A virus must:
- stick to a host cell (______)
- get into the cell (_________) and release its genome (______)
- express its genes to make proteins (_________)
- replicate its genome (_________)
- put everything together (________) and get the new virus particles out (____)

Answer 13

adhere, penetrate, uncoat, synthesis, synthesis, assembly, exit

Question 14

In the replication cycle, _____ is arguably the most important part in the viral replication cycle.

Answer 14

entry

Question 15

_________ for entry vary depending on the host cell (animal viruses don’t have to contend with a cell wall structure)

Answer 15

mechanisms

Question 16

The most common mode of entry int an animal cell is ________ ______ of an enveloped virus.

Answer 16

membrane fusion

Question 17

Viruses can enter into animal cells through ________ ______ and ___________ of an enveloped or non-enveloped virus.

Answer 17

membrane fusion, endocytosis

Question 18

Entry into _____ cells depend on damage to tissues and open spots in the cell wall.

Answer 18

plant

Question 19

These factors can allow for viruses to enter into plant cells:

Answer 19

insects feeding on plants
wind damage
hail/rain damage
fire damage
human-induced damage

Question 20

Viruses enter into ________ by punching a hole into the cell wall and transferring DNAA through the hole.

Answer 20

bacteria

Question 21

In _____ replication cycle, phages replicate inside host cells and burst open/lyse them to spread.

Answer 21

lytic

Question 22

In _________ replication cycles, the phages integrate their genome into the host cell’s genome and is replicated each time the host cell replicates.

Answer 22

lysogenic

Question 23

When a phage integrates their genome into the bacterial host cells genome, it becomes a ________.

Answer 23

prophage

Question 24

To cultivate animal viruses, ______ _______ of host cells must be used to grow the targets for the viruses.

Answer 24

tissue culture

Question 25

Tissue cultures must be kept _______ and ________-____.

Answer 25

sterile, bacteria-free

Question 26

Structural changes in host cells that are caused by viral infections.

Answer 26

cytopathic effects (CPE)

Question 27

Viral ______________ is the measurement of the quantity of a virus.

Answer 27

quantification

Question 28

Viruses are usually measured as a _____, or concentration of a virus preparation.

Answer 28

titer

Question 29

Method of viral quantification where one counts the viruses within the material and scaling up to determine titer.

Answer 29

direct count

Question 30

Method of viral quantification that is useful in phages and plant viruses.

Answer 30

plaque assay

Question 31

The ____ ______________ ______ classify viruses based on Order, Family, Subfamily, Genus, and Species.

Answer 31

ICTV classification scheme

Question 32

ICTV =

Answer 32

International Committee on Taxonomy of Viruses

Question 33

The _________ ______________ ______ is based around mRNA production methods and separates viruses into seven classes.

Answer 33

Baltimore classification system

Question 34

_______ consists only of naked RNA (infectious RNA strands).

Answer 34

viriods

Question 35

Viroids are only a=observed to cause disease in ______.

Answer 35

plants

Question 36

_________ viruses require a helper virus for their replication (e.g. hepatitis).

Answer 36

satellite

Question 37

Satellite ____ also require helper virus for replication.

Answer 37

RNAs

Question 38

______ are thought to revolve around conversion of protein conformations from normal to abnormal form over time.

Answer 38

Prions

Question 39

Prions are responsible for _____________ ___________ ________________ (TSEs), such as mad cow disease and kuru.

Answer 39

transmissible spongiform encephalopathies

Question 40

Viruses are exploited to deliver working copies of genes to replace damaged versions =

Answer 40

gene therapy