Microbiology summer 2015 Lab practical > Study guide > Flashcards

Study guide Flashcards

(40 cards)

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1
Q

Know the general lab procedures

Test tubes- _____________________________________

Plates/pipets and anything sharp- ______________________

A

1) separate into agar and broth test tubes in the racks where the hazardous waste bins are at
2) go in the sharp hazardous disposal bucket

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2
Q

what are the basic types of growth media?

A
  • Broth slant- liquid media in a culture tube
  • Agar slant- solid slanted
  • Agar deep- solid, upright media in a culture tube
  • Agar plates- solid agar in a petri dish
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3
Q

What is aseptic technique? Why is it important?

A

The transfer of bacteria from one media to another, without introducing contamination to either the bacterial culture or the media it is being transferred to.

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4
Q

How is the Aseptic technique performed?

A
  • Flame inoculating loop/needle until red hot, Cool ~15 seconds
  • Remove tube cap and pass tube opening (mouth) through flame
  • ***Hold bacteria tube in hand not holding inoculating loop/needle
  • Take bacteria from tube
  • Reflame tube opening, and recap
  • Take sterile tube, uncap and flame tube opening (mouth)
  • Place bacteria in/on new medium (inoculation)
  • Reflame tube opening and recap
  • LASTLY, REFLAME YOUR LOOP/NEEDLE!
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5
Q

calculate total magnification

A

10 times the lense magnification

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6
Q

how to properly care for the microscope.

A
  • One hand on bottom of the base and one at the arm
  • Make sure the eyepiece is at the right position
  • Lower stage all the way down
  • Set the objective lense to the lowest magnification
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7
Q

Know the difference between prokaryotic and eukaryotic cells.

Prokaryotic- _________________________________________

Eukaryotic- _________________________________________

A

1) 1-5 micrometers, no memebrane bound organelles, single chromosome, binary fission
2) covers domains archaea and bacteria, 10-100 micrometers,

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8
Q

identify the morphology of a prokaryotic cell?

A

1) Cocci, bacilli, spirochaete

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9
Q

What techniques were used in lab to isolate colonies?

A

Streak plate and Spread plate

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10
Q

What is the difference between the two methods of isolation?

A
  • Streak plate – Obtain isolated colonies by DILUTING bacteria on plate
  • Spread plate – Obtain isolated colonies by DILUTING bacteria in tubes first, then spreading each tube on a plate.
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11
Q

What are the three categories of stains?

A
  • Morphological – size, shape, arrangement
    • Simple stain and Negative stain
  • Differential – cell wall composition
    • Gram stain and Acid-fast stain
  • Structural – cell structures
    • Endospore stain and Capsule stain
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12
Q

Why is a smear prep done?

___________________________________________

How is it done?

A

1) To fix a thin layer of cells to the microscope slide prior to staining.
2) Aseptically add bacteria

Air dry

Heat fix

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13
Q

What is a basic stain?Which basic stains did we use in lab?

A

1) They’re stains that have a positively charged dye that is attracted to the slightly negative cell walls
2) Methylene Blue and Crystal Violet

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14
Q

What is an acidic stain?Which acidic stains did we use in lab?

A

1) Negatively charged stains that are repelled off the slightly negative cell wall and stain the background
2) India Ink

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15
Q

What is a simple stain useful for?

A

To Determine the morphology and arrangement

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16
Q

What is a negative stain useful for?

A
  • Not heat fixed
    • Cells maintain original shape and size without becoming distorted.
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17
Q

What is the principle behind the Gram stain?

Study These Flashcards
A

Separate bacteria into 2 groups (gram + and -)

18
Q

Study studyguides tables

19
Q

What is a capsule?

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A

Protective structure that surrounds some bacteria, protects from phagocytosis

20
Q

How is the presence of capsules confirmed?

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A

Look for a white halo around the cell (look at part W for stains)

21
Q

What is an endospore?

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A

A dormant bacteria enclosed within a tough keratin coating that is awaiting for a good environment to turn vegetative

22
Q

Under what conditions is an endospore formed?

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A

When it’s in a poor environment that it doesn’t like

23
Q

Why is steaming used in the endospore stain and the acid-fast stain?

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A
  • To force the stain into the cell
    • Acid fast- let mycolic acid “melt” and allow entrance of the stain
24
Q

What types of bacteria form endospores?

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A
  • Bacillus & Clostridium –
    • Bacillus Anthracis (anthrax)
    • Clostridium tetani (tetanus)
    • Clostridium botulinum (botulism)
    • clostridium perfringens (gas gangrene)
25
What is special about acid-fast bacteria?
It has mycolic acid, a waxy substance that prevents dehydration and chemical damage
26
What types of bacteria are acid-fast positive?
Mycobacterium- Mycobacterium leprae (leprosy), Mycobacterium Turbeculosis (tuberculosis)
27
What is fermentation?
Partial breakdown of the organic molecules and does not require oxygen
28
What are hydrolytic enzymes?
Enzymes capable of breaking down materials inside the bacterial cell or in its environment
29
What are the products of hydrolysis used for?
* Energy metabolism substrates * building new proteins (amino acids), and materials for replication (amino acids and nucleic acids)
30
Many of these enzymes worked extracellularly. Why would these enzymes not be very effective inside the bacterial cell?
Because they’re are made to break down materials found outside the cell
31
What is the IMViC (MR-VP Tests) series of tests?
* Indole (sim), * methyl red (MR-VP), * Vogues – Proskauer (MR-VP) * citrate
32
TSI test for fermentation of several sugars. Can we differentiate between which sugars are fermented?
No because the tube turns yellow when glucose alone is fermented or glucose and lactose or sucrose are fermented (24)
33
What is a selective media?
Media that encourages the growth of some organisms and prevent the growth of others
34
What is a differential media?
Media that undergoes an obvious change when a certain bacteria is present (pH changes/ Fermentation)
35
What makes EMB selective?
The salt agar, Eosin Y, and Methylene Blue don’t allow the gowth of gram + bacteria
36
What does EMB select for?
Eosin Methylene blue (the dyes used)
37
What makes EMB differential?
The carbohydrate lactose/sucrose that lets us see the ability to ferment lactose/sucrose
38
What does EMB differentiate between?
Rapid fermenters and slow fermenters
39
What pH indicator is used in EMB?
* EOSYN Y AND METHYLENE BLUE * Lower pH= slow fermenters=pink * Further Lowered pH= rapid fermenters=green metallic sheens
40
What causes the indicator to change color?
Fermentation speed
Microbiology summer 2015 Lab practical
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