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Microbiology summer 2015 Lab practical > Study guide > Flashcards

Study guide Flashcards

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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?

A

Separate bacteria into 2 groups (gram + and -)

18
Q

Study studyguides tables

A
19
Q

What is a capsule?

A

Protective structure that surrounds some bacteria, protects from phagocytosis

20
Q

How is the presence of capsules confirmed?

A

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

21
Q

What is an endospore?

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?

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?

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?

A
  • Bacillus & Clostridium –
    • Bacillus Anthracis (anthrax)
    • Clostridium tetani (tetanus)
    • Clostridium botulinum (botulism)
    • clostridium perfringens (gas gangrene)
25
Q

What is special about acid-fast bacteria?

A

It has mycolic acid, a waxy substance that prevents dehydration and chemical damage

26
Q

What types of bacteria are acid-fast positive?

A

Mycobacterium- Mycobacterium leprae (leprosy), Mycobacterium Turbeculosis (tuberculosis)

27
Q

What is fermentation?

A

Partial breakdown of the organic molecules and does not require oxygen

28
Q

What are hydrolytic enzymes?

A

Enzymes capable of breaking down materials inside the bacterial cell or in its environment

29
Q

What are the products of hydrolysis used for?

A
  • Energy metabolism substrates
  • building new proteins (amino acids), and materials for replication (amino acids and nucleic acids)
30
Q

Many of these enzymes worked extracellularly. Why would these enzymes not be very effective inside the bacterial cell?

A

Because they’re are made to break down materials found outside the cell

31
Q

What is the IMViC (MR-VP Tests) series of tests?

A
  • Indole (sim),
  • methyl red (MR-VP),
  • Vogues – Proskauer (MR-VP)
  • citrate
32
Q

TSI test for fermentation of several sugars. Can we differentiate between which sugars are fermented?

A

No because the tube turns yellow when glucose alone is fermented or glucose and lactose or sucrose are fermented (24)

33
Q

What is a selective media?

A

Media that encourages the growth of some organisms and prevent the growth of others

34
Q

What is a differential media?

A

Media that undergoes an obvious change when a certain bacteria is present (pH changes/ Fermentation)

35
Q

What makes EMB selective?

A

The salt agar, Eosin Y, and Methylene Blue don’t allow the gowth of gram + bacteria

36
Q

What does EMB select for?

A

Eosin Methylene blue (the dyes used)

37
Q

What makes EMB differential?

A

The carbohydrate lactose/sucrose that lets us see the ability to ferment lactose/sucrose

38
Q

What does EMB differentiate between?

A

Rapid fermenters and slow fermenters

39
Q

What pH indicator is used in EMB?

A
  • EOSYN Y AND METHYLENE BLUE
  • Lower pH= slow fermenters=pink
  • Further Lowered pH= rapid fermenters=green metallic sheens
40
Q

What causes the indicator to change color?

A

Fermentation speed

Microbiology summer 2015 Lab practical (4 decks)

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