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infc 180 > LO 1 > Flashcards

LO 1 Flashcards

0
Q

What are the four groups of microorganisms?

A

Protozoa, Fungi, Bacteria, Viruses

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1
Q

What is a microorganism?

A

An organism that is too small to be seen without the aid of a microscope - simple in structure and often unicellular

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2
Q

Define: Protozoa

A
  • Unicellular creature that moves by flagella or in ameboid motion - Has a nucleus and a plasma membrane - Live in water and soil, by feeding on bacteria and sm particles
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3
Q

What is a Giardia infection?

A

‘Beaver fever’ disease - the Protozoa attach to the intestinal wall by two sucking discs and cause diarrhea **antiprotozoal drugs are used as treatment

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4
Q

Define: Amoebae

A

A type of Protozoa - can invade the intestinal wall causing diarrhea and move into deeper tissue - in poor countries with poor sanitation - move by pseudopods, no flagella

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5
Q

Define: Fungi

A

A non-photosynthetic plant - has a nucleus and is enclosed by a rigid cell wall

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6
Q

What are the two types of fungi?

A

Yeasts and moulds

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7
Q

What is candida?

A

Candida sp. is a yeast disease that may cause vaginal discharge, skin infections, pneumonia and even death **antifungal drugs are used as treatment

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8
Q

Define: Yeasts

A

Unicellular oval structures that reproduces by budding

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9
Q

What type of infections are caused by moulds?

A

Atheletes foot and ringworm are infections caused by the fungus mould **antifungal drugs are used as treatment

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10
Q

Define: Moulds

A

Multicellular structure that form visible clumps of growth - Moulds start with long tubular structures (hyphae) that produce spore (responsible for the blue green color)

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11
Q

Define: Bacteria

A

Unicellular organisms typically surrounded by a rigid cell wall - No organized nucleus but can grow and reproduce

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12
Q

What can bacteria cause?

A
  • Strep throat is caused by the bacteria streptococcus which cause skin abscesses called boils - Food poisoning is caused by the bacteria salmonella from poultry ** bacterial infections are treated with antibiotics
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13
Q

T or F: there is bacteria in our pee

A

False; there is no bacteria in our pee, it’s sterile

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14
Q

Define: Viruses

A

-Smaller than bacteria and have a very simple structure - unable to grow and reproduce on their own and must rely on a living host cell to replicate the viral parts - animal, plant and bacterial cells serve as host cells for viruses

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15
Q

What are some diseases caused by viruses ?

A
  • Influenza and colds are viral infections - hepatitis, rabies and aids are more serious viral infections ** viral infections are treated with antiviral drugs
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16
Q

How are microorganisms measured?

A

In metric units called micrometers * 1 micrometer = 0.001 of a millimetre ** all microorganisms are smaller than 0.1mm=100 micrometers

*Micrometre= um

* 1000 micrometres in 1 millimetre

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17
Q

What is the size of a Protozoa? Fungi? Bacteria? Viruses?

A

Protozoa = 15-20 micrometers Fungi = 5-10 micrometers Bacteria = 0.3-5 micrometers Viruses = 0.02-0.2 micrometers

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18
Q

What is the most common microorganism found in the hospital setting?

A

Bacteria

19
Q

Bacteria:

Cocci (pleural) or Coccus (singular)

A

Spherical or round cells

20
Q

Bacteria:

Rods or Bacilli (Bacillus=singular)

A

Rectangular shaped boxes

21
Q

Bacteria:

Spirilla (Spirillum=singular)

A

Curved or spiral shaped rods

22
Q

How can bacteria be divided based on their gram stain?

A

1) Gram positive - dark bluish-black or purple colour
2) Gram negative - pink-red colour

23
Q

Why is the Gram reaction important? (3 reasons)

A

1) Identification - by gram stain and shape, 6 groups (ex. gram positive cocci, gram negative cocci)
2) Effectiveness of certain antibiotics - Penicillin G kills gram positive bacteria, but not gram negative bacteria
3) Effectiveness of certain disinfectants

24
Q

Define: Endospores

A

A structure formed by some bacteria that allows the bacterium to remain dormant for years without nurtients or moisture

* More resistant to destruction then vegetative bacteria

A small number of Gram positive rods that are able to produce a special type of spore within the bacterial cell

  • bacteria in dust, cereals, grains, and soil exist as endospores
25
Q

Define: Vegetative cells

A

Bacterial cell that do NOT contain endospores

* Gram positive rods that are able able to form spores can still exist as vegetative cells when they are actively growing and multiplying

26
Q

Define: Sporulation

A
  • Stress on cell
  • Happens when certain nutrients are depleted
  • One copy of the genetic material and a tiny amount of cytoplasm is enclosed by a layer of insulating material and the whole structure is covered with several compact layers of spore coat

Vegetative cell –> Endospore formation in cell –> free endospore

27
Q

Define: Germination

A

Spore –> Germination –> Vegetative cell

The process where a endospore germinates into a vegetative bacterium cell when moisture and nutrients are provided

28
Q

Endospores have a significant impact on ____ and ______

A

Sterilization and disinfection

29
Q

What are endospores resistant to?

A

1) Heat - most bateria are killed by heat of 60-80 degrees Celcius for 10 mins; BUT spores need to be exposed to heat of 121 degrees Celcius for 12-15 minutes for destruction
2) Disinfectants - can only kill endospores with high level of disinfectants after being used for extended periods of time

30
Q

Define: Binary Fission

A

The process by which bacteria reproduce

  • Elongation, Replication (of genetic material), Genetic material (moves to each end of cell as it grows inward), Seperation of cell (into 2 daughter cells)
31
Q

Define: Generation time

A

Time for binary fission to take place; time for population to double

  • Can be affected by temperature and the available nutrients
  • With ideal condition= 15-20 minutes
  • the quicker the generation time, the quicker the onset of symptoms
32
Q

Define: Colony

A

A visble mass of bacteria on a solid medium that have grown from one bacterial cell

33
Q

Define: Growth curve

A

The phases of growth (lag, log, stationary, death) bacteria go through when introduced into a culture medium

34
Q

Growth curve:

Define: Lag phase

A

Phase where bacteria are placed in a new environment and there is little to no increase in numbers for a short period of time

* cells are adapting to their new environment

  • lag phase time varies
  • Lag phase is 2 hours in food which means it can be left out for 2 hours before bacteria begin to grow

**Also called incubation period where there are no symptoms

35
Q

Growth curve:

Define: Log phase

A

Period of maximum growth of bacteria

  • cells are dividing at a constant rate

**also called Acute stage: Full blown symptoms; also part of incubation period

36
Q

Growth curve:

Define: Stationary phase

A

Phase where bacteria exhaust their supply of nutrients and stop growing and multiplying

* # of live bacteria stays constant during this period

*Symptoms are no better, no worse but still no sign of recovery

37
Q

Growth curve:

Define: Death phase

A

Phase where the bacterial cells start to die and the number of live cells decreases

-most die in a short amount of time, others can linger for years

*Those that survive the longest are the ones that form spores

**Also called convalescent period where the symptoms subside and it covers the time until complete recovery

38
Q

How do viruses vary from bacteria?

A

1) They are obligate intracellular parasites and only multiply when inside a living host
- Can’t grow in foods, water, bacterial culture or medications
2) They contain a single type of nucleic acid (either DNA or RNA) *other forms of life contain both*

39
Q

What are viruses composed of?

A

1) They possess a protein coat surrounding the nucleic acid
2) Some also have an envelope composed mainly of lipids, while others have spikes protruding from the lipid envelope.

*Lipid viruses are generally easier to kill with disinfectants

40
Q

What has to happen in order for animal virsues to multiply?

A

1) In order for a virus to multiply in a host, it must attach to complementary receptor sites on the surface of the host’s cells
2) The virus is then taken in by endocytosis where the membrane folds inwards trying to contain the virus
3) As the host cell attempts to destroy the contents of the vesicle, the outer protein coat is digested and the nucleic acid is released inside the host cell

41
Q

Multiplication of a DNA virus

A

p.11

42
Q

Infection of a host cell with virus usually kills the host cell due to which 3 things?

A

1) Lysis of the cell when it fills with virus particles
2) Diversion of the cell’s metabolic pathways to the manufacture of viral particles
3) Destruction of the virus-infected cell by the lymphocytes of the cellular immune system

43
Q

Define: Oncogenic viruses

A

Viruses that can alter the nucleic acid of the host cell in such a way that the cell is transformed to a tumour cell

  • ex. hepatitis B virus because it can lead to liver cancer
44
Q

Do antibiotics have an effect on viral replication?

A

NO; antibiotics are directed against metabolic pathways of bacteria NOT viruses

45
Q

Are there many drugs used to inhibit the replication of viruses?

A

No because they cannot be used or they would destroy host cells

  • only a few antiviral drugs such as Acyclovir to control genital herpes
46
Q

Enveloped virus vs. Unenveloped (naked) virus

A

Enveloped - a virus particle surrounded by a lipid envelope

Unenveloped - a virus consisting of nucleic acid and protein but no lipid envelope

infc 180 (4 decks)

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