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Medical And Microbiology > Unit 1 C > Flashcards

Unit 1 C Flashcards

1
Q

Pasteur developed a vaccine for the ________virus.

A

Rabies

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2
Q

Viruses were discovered by filtering infectious fluid through a filter designed to trap

A

Bacteria

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3
Q

Using your textbook, describe the significance of viruses being recognized as “filterable.”

A

This showed that something “living” (at least pathogenic things) that was smaller than bacteria existed, though we could not yet see it.

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4
Q

Are there any organisms on the planet that are not targeted by at least one virus?

A

No, all organisms are targeted by at least one virus.

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5
Q

Infectious particle

A

classification of viruses, rather than organisms

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6
Q

Active or inactive

A

rather than alive or dead

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7
Q

Virion

A

infectible form of a virus outside of a host cell.

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8
Q

Obligate intracellular parasites

A

cannot multiply unless they invade specific host cell types.

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9
Q

What percent of the human genome originated from viral infections?

A

8% of our DNA is viral genes.

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10
Q

What percent of bacterial genomes, on average, originate from viral infections?

A

10-20% of bacteria genome is from viruses.

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11
Q

Using your textbook, summarize arguments on both sides of the debate regarding the classification of viruses as living organisms.

A

Viruses as living organisms; they have genes (many of which are shared with living organisms) and they enter into other organisms and use them to live and grow.

Viruses as nonliving organisms: they are acellular meaning they do not have cells. Living things by definition have cells.

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12
Q

Using your textbook, summarize the properties of viruses in your own words.

A

Not cells

Are obligate parasites

Do not have all characteristics of life

Inactive unless inside a host cell

Protein shell surrounding nucleic core

Found everywhere and has a major impact on all life

Small between 20-1000 nm

Has either DNA or RNA be not both
Can be double-stand or single-
standed

Carries moleucules to determine specificity to attach to host cells

Takes host cells genes to multiply

Lack enzymes for metabolic processes

Lack machinery to make proteins.

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13
Q

What is the size range of most viruses?

A

0.02 m to 1 m

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14
Q

Viruses lack protein synthesizing machinery, so how do they get their proteins made?

A

They rely on their host cells. They control and invade host cells

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15
Q

Capsid

A

shell surrounds the nucleic acid.

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16
Q

Nucleocapsid

A

capsid & nucleic acid together

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17
Q

Envelope

A

outside of the capsid, not found in all viruses. Usually a modified piece of the host cell membrane.

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18
Q

Capsomere

A
  • identical protein subunits that spontaneously self-assemble to form the capsid
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19
Q

Compare & contrast the structures of a naked icosahedral virus & an enveloped icosahedral virus.

A

An enveloped icosahedral virus has an envelope surrounding the capsid; whereas a naked icosahedral virus lacks an envelope.

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20
Q

Helical

A

Rod-shaped capsomere that form a continuous helix around the nucleic acid

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21
Q

Complex

A

found in bacteriophages, have multiple types of proteins, take shapes that are not symmetrical.

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22
Q

Icosahedral

A

Three-dimensional, 20-sided figure with 12 evenly spaced corner (most common).

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23
Q

What are spikes & what do they do? Where are they located on a naked virus? On an enveloped virus?

A

Spikes allow viruses to dock with their host cells, they are found wither on the nucleocapsid or envelope. They are protruding glycoproteins essential for attachment to the host cell.

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24
Q

Why don’t viruses need as many genes as cells?

A

Viruses do not need as many genes because they are obligatory parasites, they do not need to have all the machinery genes because it uses the hosts machinery genes.

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25
Q

What types of genomes can viruses have? (You should know nucleic acid types, strand number, etc.)

A

Double-stranded DNA

Linear Double-stranded DNA

Single-stranded DNA

Single-stranded + sense RNA

Single-stranded - sense RNA

Double-stranded RNA

Single-stranded RNA reverse transcriptase

26
Q

Polymerase

A

synthesize DNA & RNA

27
Q

Replicases

A
  • copy RNA
28
Q

Reverse transcriptase

A

synthesizes DNA from RNA

29
Q

How were viruses originally classified, & what problems arise from this initial classification scheme?

A

They were originally classified by size only (also pathogenic properties or ecological/transmission characteristics) multiple different viruses would have originally been grouped together.

30
Q

Know the suffixes use to define viral scientific names.

A

-virales: order
-viridae: family
-virinae: subfamily
-virus: genus

31
Q

Describe the purpose of the ICTV.

A

To combat the problem with viruses being named multiple things. Their task was to create a universal system of viral classification. Used by all virologists.

32
Q

Viral strain

A

different isolates of the same virus that come from different geographic locations.

33
Q

Viral variant

A

a virus whose phenotype differs from the original wild-type strain.

34
Q

Use Table 6.3 in your textbook to learn the scientific name (order, family, genus, & species) of 2 viruses.

A

Caudovirales -> Myoviridae -> SPO1-like virus -> Bacillus phage (host is Bacterium)

Herpesvirales -> Hepesviridae -> Simplexvirus -> Human herpesvirus 2 (host is Animal)

35
Q

What are the six steps of viral replication cycles?

A
  1. Adsorption
  2. Penetration
  3. Uncoating
  4. Synthesis
  5. Assembly
  6. Release (from the host cell)
36
Q

For each of the RNA virus genome types discussed, understand how each type of virus gets to a point where mRNA is produced, as well as how that virus gets its genome copied.

A
37
Q

For each of the DNA virus genome types discussed, understand how each type of virus gets to a point where mRNA is produced, as well as how that virus gets its genome copied.

A
38
Q

Define adsorption vs. absorption.

A

Adsorption- to attach (like a virus)

Absorption- to soak in (like a paper towel)

39
Q

Which step in a viral replication cycle accounts primarily for a virus’ host range or cell tropisms?

A

Step 1 (adsorption) determines host range.

40
Q

In what two ways do animal viruses penetrate/uncoat within cells?

A

Endocytosis followed by uncoating: entire virus is engulfed by the cell & enclosed in a vesicle, where enzymes uncoat, or dissolve, the envelope/capsid

Fusion of the viral envelope allows entry & uncoating of the virus in the cytoplasm of the cell.

41
Q

In what two ways do animal viruses exit cells?

A

Budding
Exocytosis
Naked viruses do lysis

42
Q

Provide two examples of cytopathic effects caused by viral infection in animal cells.

A

Syncytia: fusion of multiple hot cells into single large cells

Inclusion bodies: compacted masses of viruses or damaged cell organelles in nucleus or cytoplasm

43
Q

Describe how persistent infections arise within humans & provide 3 examples of viruses capable of doing this.

A

Carrier relationship- hide in cell’s nucleus, the cell harbors the virus. Provirus- viral DNA is incorporated into the DNA of the host. There are called retroviruses, HIV, Herpes, and measles.

44
Q

If you get herpes cold sores or chickenpox, does the virus ever “go away” from your body?

A

No, although you are not always sick these viruses stay in your body for life.

45
Q

Describe three ways in which some viruses can be oncogenic.

A

Viral oncogenes incorporate into host cell DNA and produce proteins that lead to uncontrolled cell growth. (some retroviruses)

Viral genes affect expression of host oncogene leading to uncontrolled cell growth. (other retroviruses)

Viral genes directly produce proteins that lead to uncontrolled cell growth. (DNA Tumor Viruses)

46
Q

Define “bacteriophage.”

A

Viruses that infect bacteria. (known as bacteria eaters)

47
Q

Be able to make a simple diagram showing a lytic & lysogenic bacteriophage replication cycle.

A
48
Q

How do bacteriophage infections sometimes make bacteria more pathogenic to humans?

A

Sometimes they cause the production of toxins and enzymes that cause pathology in humans.

49
Q

Provide an example of a bacterial infection that is worsened by lysogenic conversion. You may need to research how a particular toxin causes damage in the body.

A

Diphtheria toxin- this toxin enters into the cell cytoplasm and inhibits protein synthesis.

50
Q

Why is the number of viral infections so hard to calculate?

A

Most cause acute infections that do not result in hospitalization.

51
Q

Discuss why antiviral drugs are more difficult to design than antibacterial drugs.

A

Viruses mutate at a rapid rate and viruses blend in with our cells better than bacterium.

52
Q

What are the features of spongiform encephalopathies?

A

Implicated in chronic, persistent disease.

Brain tissue removed from affected animals resembles a sponge.

Mental derangement, loss of muscle control, universally fatal

Cause by prions

53
Q

Describe how prions lead to brain damage?

A

It causes brain shrinkage and deterioration.

54
Q

Sporadic disease

A

Sporadic fatal insomnia

Misfolded protein

Difficulty falling asleep, difficulty waking, weight loss, and excessive tears in the eye.

55
Q

Genetic prion disease

A

Familial Creutzfeldt-Jakob Disease (fCJD)

Inherited mutation in the prion protein gene (PRNP)

Balance and coordination problems, memory loss, and impaired thinking.

56
Q

Acquired prion disease

A

Variant Creutzfeldt-Jakob Disease (vCJD)

Linked to eating beef contaminated with bovine spongiform encephalopathy (mad cow disease)

Personality changes and psychiatric symptoms (depression/withdrawal) and stumbling, falls, and difficulty walking.

57
Q

Scrapie

A

sheep, goats

58
Q

Bovine Spongiform encephalopathy (‘’mad cow disease”)

A

cows

59
Q

Chronic wasting disease (CWD)

A

deer, elk, etc.

60
Q

In what ways can prion diseases be acquired/transmitted?

A

Genetics (increased risk with diagnosis in a blood relative)

Age (sporadic prion diseases tend to develop in older adults, who have had more time to experience the protein misfolding event)

Animal products (consuming contaminated animal products, especially nervous tissue)

Medical procedures (contaminated medical equipment or contaminated nervous tissue from various graft/transplant procedures)

Medical And Microbiology (16 decks)

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