Viruses

Question 1

Obligate intracellular parasites lacking the capacity to make energy or substrates

Answer 1

Viruses

Question 2

How do viruses replicate?

Answer 2

By assembly of parts
NOT binary fission

Question 3

The basic structure of a virus is nucleic acid surrounded by a _____ coat

Answer 3

Protein coat

Question 4

Is viral nucleic acid circular or linear?

Answer 4

Can be either

Question 5

Outer protein coat of viruses made of capsomeres (subunits forming pentons and hexons)

Answer 5

Capsid

Question 6

The viral capsid is an outer protein coat made of these

Answer 6

Capsomeres (subunits forming pentons and hexons)

Question 7

What gives viruses their shape?

Answer 7

Capsid

Question 8

Viral architecture that is resistant to drying, acid, detergents, and bile

Answer 8

Capsid

Question 9

Protein coat with the nucleic acid inside

Answer 9

Nucleocapsid

Question 10

Lipid membrane acquired from a host cell membrane through budding
Susceptible to organic solvents

Answer 10

Envelope

Question 11

The viral envelope is susceptible to this

Answer 11

Organic solvents

Question 12

The viral envelope is this

Answer 12

Lipid membrane acquired from host cell membrane through budding

Question 13

The space between the capsid and the envelope

Answer 13

Tegument

Question 14

The tegument is the space between these

Answer 14

Capsid and envelope

Question 15

Are host proteins found in isolated enveloped viruses?

Answer 15

No

Question 16

These can associate with the glycoproteins in the viral envelope to localize capsid formation to the appropriate location

Answer 16

Viral matrix proteins

Question 17

What localizes viral capsid formation to the appropriate location?

Answer 17

Viral matrix proteins that associate with glycoproteins in the envelopes

Question 18

Complete infectious virus particle

Answer 18

Virion

Question 19

For naked viruses, this is the virion

Answer 19

Nucleocapsid

Question 20

For enveloped viruses, this is the virion

Answer 20

Nucleocapsid with the envelope

Question 21

6 stages of the lytic replication cycle for animal viruses

Answer 21

1. Attachment
2. Penetration and uncoating
3. Targeting to the site of reproduction
4. Synthesis (txn and tln)
5. Assembly
6. Release

Question 22

2 enzymes required for some viruses that are not found in human cells

Answer 22

RNA-dependent DNA pol (make DNA from RNA)
RNA-dependent RNA pol (make RNA from RNA)

Question 23

Do DNA viruses require extra enzymes not found in the host?

Answer 23

No; just use host enzymes

Question 24

In the early phase of viral genome replication, these products are made first

Answer 24

Early gene products: non-structural proteins
Viral polymerases and regulatory molecules needed for further replication

Question 25

In the late phase of viral genome replication, these products are made

Answer 25

Structural proteins, mainly capsid proteins Genome replication triggers this step

Question 26

What type of host cells are required for viral genomic replication and expression?

Answer 26

Rapidly growing host cells

Question 27

Do small or large viruses typically use host polymerases?

Answer 27

Small

Question 28

Do small or large viruses typically encode their own polymerases?

Answer 28

Large

Question 29

Type of virus that can be directly translated by host cell machinery to make virus proteins

Answer 29

+ssRNA

Question 30

All RNA viruses except retroviruses require this enzyme for genome replication

Answer 30

RNA-dependent RNA pol

Question 31

3 types of viruses that require their own RNA-dependent RNA pol

Answer 31

+ssRNA, -ssRNA, and dsRNA

Question 32

Type of virus that must encode an RNA-dependent RNA pol that is packaged in the capsid

Answer 32

-ssRNA

Question 33

Difference in polymerase requirements between +ssRNA and -ssRNA viruses

Answer 33

Both require their own RNA-dep RNA pol, however -ssRNA must have it packaged in the capsid

Question 34

Type of RNA virus that can be directly translated

Answer 34

+ssRNA

Question 35

A retrovirus virion contains these 3 things

Answer 35

2 identical +ssRNA molecules 2 tRNA molecules Reverse transcriptase (RNA-dep DNA pol)

Question 36

How does reverse transcriptase replicate retroviral genome?

Answer 36

Produces cDNA copy of the RNA genome in the cytoplasm cDNA enters the nucleus and integrates into the host genome Host txn makes viral mRNAs from the integrated cDNA template

Question 37

Reverse transcriptase produces cDNA from the viral RNA genome in this intracellular location

Answer 37

Cytoplasm cDNA then enters the nucleus and integrates into the host genome

Question 38

When does viral assembly begin?

Answer 38

Begins when viral “pieces” reach a high enough concentration to induce self assembly

Question 39

Scaffolding proteins may be involved in this step of viral replication

Answer 39

Assembly

Question 40

DNA viruses assemble in this intracellular location

Answer 40

Nucleus

Question 41

RNA viruses assemble in this intracellular location

Answer 41

Cytoplasm

Question 42

Type of viruses that assemble in the nucleus

Answer 42

DNA

Question 43

Type of viruses that assemble in the cytoplasm

Answer 43

RNA

Question 44

Step of viral replication where enveloped viruses acquire the lipid membrane in a process known as budding

Answer 44

Release

Question 45

Enveloped viruses acquire the lipid membrane during release in a process known as this

Answer 45

Budding

Question 46

Budding (process where enveloped viruses acquire the lipid membrane) can occur in these 4 cellular locations

Answer 46

Plasma membrane Nuclear membrane ER Golgi

Question 47

Viruses cause pathologic effects, called cytopathic effect, by these 4 mechanisms

Answer 47

Lysis Vacuolization Inclusion bodies Cell fusion (syncytia)

Question 48

Viral infections that fail to produce any symptoms in the host are called:

Answer 48

Inapparent or subclinical

Question 49

2 components of viruses that can be identified in cytologic examination

Answer 49

Syncytia and inclusion bodies

Question 50

Laboratory diagnosis method: May not be a standard clinical laboratory technique but can be used to detect and identify a virus

Answer 50

Electron microscopy

Question 51

Laboratory diagnosis method: Is usually unnecessary and avoided to reduce the risk to laboratory personnel

Answer 51

Virus isolation

Question 52

In serology, a ______ -fold increase in antibody titer is needed between acute phase and convalescent sera

Answer 52

4 fold increase

Question 53

Detection of this Ab is likely an active acute infection

Answer 53

IgM

Question 54

Proteinaceous infectious agent, linked to a number of fatal human diseases

Answer 54

Prion

Question 55

Prions cause this

Answer 55

Brain degeneration Brain tissue develops sponge-like holes termed transmissible spongiform encephalopathies Symptoms may not appear for years after infection (slow infection)

Question 56

Transmissible spongiform encephalopathies are indicative of this

Answer 56

Prions

Question 57

Do symptoms from prion infection appear rapidly or slowly?

Answer 57

Slow infection; symptoms may not appear for years after infection

Question 58

Normal cellular PrP protein has this secondary structure

Answer 58

Alpha helices

Question 59

PrP with alpha helices is this

Answer 59

Normal cellular PrP protein (made by all mammals)

Question 60

PrP with beta pleated sheets is this

Answer 60

Disease causing form called prion PrP

Question 61

Prion PrP (disease causing form) has this secondary structure

Answer 61

Beta pleated sheets

Question 62

Prion PrP (disease causing form) is resistant to these 3 things

Answer 62

Proteases, nucleases, and UV light

Question 63

Characteristic of prions that makes it a slow infection

Answer 63

Prion PrP changes shape of cellular PrP so it becomes prion PrP