Viruses and Prions

Question 1

viruses are

Answer 1

submicroscopic infectious particles

Question 2

virus characteristics

Answer 2

acellular (no cells)
obligate intracellular pathogens
DNA or RNA
infect all known life
no metabolism

Question 3

when were viruses discovered

Answer 3

1898

Question 4

virus size

Answer 4

20 - 1000 nm long

Question 5

virion

Answer 5

single infectious virus particle

Question 6

virion parts

Answer 6

exterior protective protein capsid
genetic material

Question 7

capsid

Answer 7

protein shell
bulk of a vision
capsomere subunits

Question 8

animal viruses can be

Answer 8

helical
icosahedral
complex

Question 9

bacteriophage

Answer 9

complex capsids
attach to cell surface to inject genetic material

Question 10

envelope

Answer 10

lipid-based
arises from budding off host cell
animal viruses may be enveloped
bacteriophages are not enveloped

Question 11

naked (nonenveloped)

Answer 11

viruses that lack an envelope
cell lysis (bursting)

Question 12

spikes

Answer 12

peplomers
protrusions from capside or envelope
glycoproteins
aid in attachment and entry to host cell

Question 13

glycoprotein

Answer 13

proteins with sugars

Question 14

stages of animal virus replication

Answer 14

1. attachment
2. penetration
3. uncoating
4. replication
5. assembly
6. release

Question 15

attachment

Answer 15

naked viruses attach to host cells using capsid proteins
other viruses use spike proteins

Question 16

host range

Answer 16

collection of species a virus can infect

Question 17

tropism

Answer 17

range of tissues or cells a virus can infect inside a given host
specificity - “lock and key”

Question 18

penetration

Answer 18

enveloped - endocytosis or fusion
naked - endocytosis

Question 19

uncoating

Answer 19

capsid is digested by enzymes

Question 20

replication needs to do 2 things

Answer 20

1. replicate nucelic acid
2. produce new structural proteins

Question 21

DNA virus replication

Answer 21

replicates DNA and makes RNA
RNA produces viral proteins
proteins and new DNA make virions

Question 22

RNA virus replication

Answer 22

RNA makes new proteins
RNA-dependent RNA polymerase produced more RNA molecules
these work together to build new virion

Question 23

retrovirus (RNA)

Answer 23

reverse transcriptase to produce DNA
then follows DNA replication process

Question 24

assembly

Answer 24

formation of new virions
packaging of genome

Question 25

release

Answer 25

enveloped - budding naked - lysis of host cell

Question 26

viral infection types

Answer 26

acute chronic latent systemic

Question 27

acute infection

Answer 27

continuous viral replication

Question 28

chronic infection

Answer 28

slow release of viral particles may or may not kill host cell

Question 29

latent infection

Answer 29

acute, but virus enters quiescent period (dormant) no new viral progeny produced reactivation

Question 30

systemic infection

Answer 30

in plants the plant rarely recovers

Question 31

oncogenic viruses

Answer 31

causes ~ 10 - 15% of cancers stimulate uncontrolled host cell division decreases host cell responsiveness to death signals ex. HPV

Question 32

what do bacteriophages infect

Answer 32

bacteria

Question 33

bacteriophage replication

Answer 33

lytic or lysogenic

Question 34

lytic replication pathway

Answer 34

1. adsorption 2. penetration 3. replication 4. assembly 5. maturation 6. release

Question 35

temperate phages

Answer 35

can be lytic or lysogenic (both are possible)

Question 36

lysogenic replication pathway

Answer 36

1. adsorption 2. penetration 3. integration (cell division or lytic cycle entry) 4. replication 5. assembly 6. maturation 7. release

Question 37

integration

Answer 37

prophage - viral genes in host chromosomes

Question 38

prophage conversion

Answer 38

confer new pathogenicity factors to bacteria

Question 39

prions

Answer 39

infectious, misfolded proteins

Question 40

prion characteristics

Answer 40

no genetic material do not replicate in classical sense made from proteins most abundant in brain

Question 41

what do prions cause

Answer 41

transmissible spongiform encephalopathies

Question 42

prions in sheep cause

Answer 42

scrapie

Question 43

prions in cows cause

Answer 43

bovine spongiform encephalopathy (BSE) "Mad Cow Disease"

Question 44

prions in humans cause

Answer 44

kuru (from cannabalism) Creuzfeldt-Jakob disease (CJD)

Question 45

prions come from

Answer 45

PrPC (made by all mammals)

Question 46

prions form

Answer 46

amyloids - abormal aggregates

Question 47

infectious form on PrPC

Answer 47

PrPSc

Question 48

prion transmission

Answer 48

acquired - direct exposure genetic - familial sporadic - unknown (85% of cases)