Microbiology 2 Flashcards

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1
Q

The general steps in viral replication (in order) are?

A

adsorption, penetration, synthesis, assembly, release.

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1
Q

A major difference in the replication of animal viruses and bacteriophages is the ______ step

A

Penetration

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1
Q

Viral cycles that end in release of the new phages and immediate destruction of the host bacterial cell are referred to as _______.

A

Lytic

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1
Q

How does bacteriophage DNA get into the host cell?

A

It’s injected

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2
Q

the statement that best describes the role of viral surface proteins or spikes.

A

Viral spikes provide means of attachment to host cell surface.

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3
Q

What term describes the type of bacteriophage infection in which the host bacteria are lysed and killed as a result of the infection?

A

Lytic

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3
Q

What term describes the type of bacteriophage infection cycle where the bacteriophage DNA is inserted into the host cell DNA as a prophage and the infected bacteria can continue to grow and divide?

A

Lysogenic

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3
Q

Please order the following steps to reflect the order in which they occur in the replication cycle of an animal virus.

A

Adsorb, penetration, synthesis, assembly, release.

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4
Q

Which of the following descriptions fits a chronic viral infection?

A

Characterized by continuous production of low levels of viral particles, even in the absence of disease symptoms. The organism is usually still highly infectious during this time.

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5
Q

Which of the following describes a latent viral infection?

A

Long periods of time with essentially zero viral replication, punctuated by outbreaks of active replication and disease manifestation. Infected individuals are largely non-infectious between outbreak periods.

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6
Q

Steps of lytic cycle or typical bacteriophage?

A
  1. Attachment:
    Phage attaches to specific receptors.

2: Genome Entry:
Tail contracts, DNA is injected into the bacterial cell.

  1. Synthesis:
    Phage genome is transcribed, proteins are translated. Phage DNA is replicated.
  2. Assembly:
    Phage components are assembled into mature virion particles.

5: Release:
Bacterial cell lyses, many new infectious virions are released.

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7
Q

Please place the steps for animal virus replication in the correct sequence.

A

1: Virus attaches to receptors on the host cell cytoplasmic membrane.

2: Virus enters the host cell by fusion or endocytosis.

3: Viral genome is uncoated.

4: Structural and catalytic viral genes are expressed.

5: Multiple copies of the viral genome are synthesized.

6: New viral particles assemble and mature.

7: Viruses are released from the host cell by budding or during apoptosis of the host cell.

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8
Q

Some phages are medically important for all of the following reasons EXCEPT

A

they also infect eukaryotic cells.

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9
Q

A virus usually infects only certain types of cells due to

A

interactions between viral and cellular surface molecules.

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10
Q

Which of the following is required for prion replication?

A

Abnormal prion protein

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11
Q

Nematode characteristics?

A

Roundworms, cylindric body, an example is pinworms, digestive tract including mouth and anus.

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12
Q

Cestode characteristics?

A

Lack digestive system; absorb nutrients from host. Flat-ribbon shaped bodies. An example is a tapeworm. Intermediate hosts include cattle and pigs.

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13
Q

Trematode characteristics?

A

Flukes. One opening for nutrient intake and exit of wastes. Flat-leafed shaped bodies. An example is schistosomes.

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14
Q

Which of the following statements about fungal structure are TRUE?

A

Can be both unicellular and multicellular.

Group of cells together or a series is called a hyphae or (Hyphal mass).

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15
Q

Which of the following statements about the economic impact of fungi is FALSE?

A

Fungi commonly cause serious human diseases that lead to loss of work hours.

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16
Q

Which of the following statements about the medical importance of algae are TRUE?

A

Some algae produce powerful neurotoxins that accumulate in shellfish.

Examples of algal toxins that impact humans are saxitoxins and gonyautoxin.

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17
Q

Which of the following about fungi is FALSE?

A

All fungi are unicellular.

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18
Q

Limited host range?

A

The range of host cells that a virus can infect.

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18
Q

Helminths are most commonly transmitted to humans by

A

the gastrointestinal route.

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19
Q

Not alive viruses

A

inactive outside host cell, no cellular structure, no physiology. Cannot infect host.

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19
Q

Obligate intracellular parasites?

A

Require a host cell (and host machinery) to reproduce.

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20
Q

Alive viruses

A

No physiology but viruses alter the physiology of the host. Able to infect host.

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21
Q

Species virus

A

Specific bacteriophages

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21
Q

Structure of virus

A

Protein shell (capsid), genome (DNA or RNA), no ribosomes, mitochondria and no metabolism

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22
Q

Narrow virus

A

Identity of spikes on the virus.

Spikes will then find matching receptors on host cell surface.

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23
Q

Classification of viruses?

A

Classification strategy

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24
Q

Virus sizes?

A

Viruses are very small, the size of nanometers (nm). Nanometers are 1/100th of a micron.

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25
Q

Smallest virus?

A

Porcine circovirus–> causes wasting disease in pigs 17nm.

26
Q

What is a virion?

A

Complete, fully developed virus particle.

27
Q

What is nucleic acid genome?

A

DNA or RNA; double or single stranded; linear or circular.

28
Q

What is a capsid?

A

A protein coat made of capsomeres (subunits).

29
Q

What are spikes?

A

Surface receptors.

30
Q

What is enveloped?

A

Portion of host cell derived membrane surrounding virus.

Only present in some viruses*

31
Q

What is helical morphology?

A

Hollow, cylindrical

32
Q

What is icosahedral/polyhedral morphology?

A

Many sided.

33
Q

What is complex morphology.

A

Head containing DNA, collar, sheath, base plate and tail fibers.

34
Q

What are preformed enzymes?

A

Quite common in certain types of HIV retroviruses.

35
Q

Order of virus taxonomy?

A

Ends in - virales

36
Q

Family of virus taxonomy?

A

ends in -viridae

37
Q

Sub family of virus taxonomy?

A

ends in -virinae

38
Q

Genus of virus taxonomy?

A

Ends in -virus

39
Q

Virus species?

A

viruses that have the same genetic info and host range.

40
Q

What is the Baltimore classification?

A

Classifies viruses into 7 groups in roman numerals. Determines lifecycle mechanics of viruses.

41
Q

What is the simplified virus lifecycle?

A
  1. invade host cell: receptors and spikes (need to match).
  2. take over the host cell machinery: cell’s machinery produces viral proteins and copies virus genome.
  3. assemble and release new virions
42
Q

Bacteriophage medical relevance?

A

Many bacteria will only be pathogenic when/if they are infected by a particular bacteriophage.

43
Q

Lytic cycle?

A

Attachment: the phage attaches to the surface of host cell.

Penetration: The viral DNA enters host cell.

Biosynthesis: Phage DNA replicates and phage proteins are made.

Maturation: New phage particles are assembled.

Lysis: The cell lysis releasing the newly made phages.

44
Q

Lysogenic cycle?

A
  1. The phage infects a cell
  2. the phage DNA becomes incorporated into host genome.
  3. cell divides, prophage DNA is passed on daughter cells.
  4. under stressful conditions the prophage DNA is excised from bacterial chromosome and enters the lytic cycle.
  5. Phage DNA replicates and phage proteins are made.
  6. New phage particles are assembled.
  7. The cell lyses releasing the newly made phages.
45
Q

What is transformation?

A

Genetic conversion that causes a cell to become cancerous.

46
Q

Oncogenic virus?

A

Viruses that insert DNA and cause cancer.

46
Q

What are oncogenes?

A

Normal genes that cause cancer when they’re mutated.

47
Q

What is latent?

A

Virus that remains asymptomatic for long intervals. “Outbreaks” during reactivation of virus-changes in immunity or stress.

48
Q
A
49
Q

What is persistent/chronic?

A

Illness occurs gradually, long term, and generally fatal.

49
Q

What is PrPSC?

A

Misfolded form = accumulates in brain tissue.

49
Q

What is the prion protein?

A

An otherwise normal protein becomes misfolded (changes structure.)

49
Q

What are prions?

A

They are inherited or transmissible (ingestion, transplants or surgical instruments) but not spread by breathing in/coughing on someone.

50
Q

What is Diarrhea?

A

Water-borne

Amebic dysentery

50
Q

What is PrPC?

A

Normal = cell surface receptor

50
Q

What are protozoa?

A

Single-cellular, free-living heterotrophs.

Require water for living and reproducing.

Classifcation in flux.

50
Q

What is Trypanosoma?

A

Some regions of African inhabitable because of things that came from this. (African sleeping disease)

50
Q

What are nematodes?

A

Many are parasitic, most are beneficial. Round bodies, unsegmented, separate sexes. Usually complete lifecycle in 1 host. Complex lifecycles.

50
Q

Insect vector?

A

Vectors are most infectious hosts to another

51
Q

What are platyhelminths (flatworms) and cestodes (tapeworms)?

A

Flat, segmented, hermaphroditic, no digestive tract. Must get nutrients from hosts. They have multiple hosts.

52
Q

What are platyhelminths (trematodes)(flukes)?

A

All parasitic; most are hermaphroditic.

53
Q

What is a definitive host?

A

Houses adult form, site of reproduction.

54
Q

What is fungal morphology?

A

Fleshy, Yeasts and dimorphic.

55
Q

What is fleshy morphology?

A

Thallus: Fungal body
Mycelium: Series of cells together (hyphae) or “hyphal mass”.

56
Q

What is yeast morphology?

A

Single-celled and look like bacteria

57
Q

What is dimorphic morphology?

A

Yeast or mycelium; T-dependent, pathogenic fungi.

58
Q

How are fungi classified?

A

Classification by strategy, based on how they reproduce.

59
Q

Sexual fungi reproduction?

A

Hyphal fusion –> mushroom –> Spores

60
Q

Asexual fungi reproduction?

A

Fragmentation, budding

61
Q

What is the medical relevance of fungi?

A

Allergy: Spores

Infectious (opportunists): tend to only infect when it’s favorable.
- Usually, superficial infections so on the outside of the body and not the inside.

Toxins: Aflatoxin and ergotism.

62
Q

Algae characteristics?

A

Single-cellular, aquatic, and photosynthetic (autotrophs)

63
Q

Toxins of algae?

A

Saxitoxin, gonyautoxin.

Bioaccumulation in shellfish.

Paralytic shellfish poisoning.

64
Q

Arthropods characteristics?

A

Mites:
- Demodex: inhabit at hair follicles
-Chiggers: get in skin
-Scabies: Adult form of mites

65
Q
A