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BIO1337 - Microbiology > Bacterial Staining > Flashcards

Bacterial Staining Flashcards

1
Q

What is the product of magnification of the ocular lens of the magnification of an objective lens?

A

Magnification of a light microscope

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2
Q

When can oil immersion be using a light microscope?

A

Only use for samples that are fixed ordead

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3
Q

How do you calculate the resolution of a light microscope?

A

Resolution = 0.5 (wavelength) / numerical aperture

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4
Q

Which type of staining is the most used for staining procedure in microbiology?

A

Gram stain

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5
Q

What is the advantage of differential stain?

A

Does not stay in all kinds of cells the same colour

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6
Q

What colour does a Gram-positive bacteria show on the Gram stain?

A

Purple colour

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7
Q

What colour does a Gram-negative bacteria show on the Gram stain?

A

Pink colour

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8
Q

How do you prepare cells for Gram staining?

A
  • thin-film of cells from culture applied to slide
  • Air dried
  • flame fixes cells glass
  • first dye with crystal violet for one minute
  • rinse with water
  • flood with iodine for three minutes
  • rinse with water
  • flood with ethanol for 20 seconds
  • Purple colour will show if Gram-positive
  • For Gram-negative need to add safranin for 1-2 minutes
  • Rinse with water before viewing
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9
Q

Why do we use crystal violet?

A

Positively charged and binds with high affinity to negatively charged molecules

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10
Q

What does crystal violet an iodine form?

A

Complex

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11
Q

Why is it important to use crystal violet and iodine in a Gram stain?

A

Difficult to remove dye from the cells if complex formed

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12
Q

What does ethanol extract from the Gram-negative bacteria?

A

Crystal violet

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13
Q

Why does ethanol not extract the crystal violet from a Gram-positive bacteria?

A

Gram-positive have a thick peptidoglycan cell wall

Ethanal causes dehydration causing pores to close and prevent crystal violet from leaving

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14
Q

What solutions can be used for simple staying?

A

Crystal violet/safranin/methylene blue

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15
Q

How do use a simple stain?

A
  • Use stain

- Rinse of with water

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16
Q

Why do we use simple stain?

A

Size, shape and arrangement of cells

17
Q

How does crystal violet stain?

A

Stains most bacteria uniformly

18
Q

How does safranin stain?

A

Stains most bacteria pink or red

19
Q

How does methylene blue stain?

A

Stains bacteria light blue

20
Q

What are the different types of differential stains?

A
  • Gram stain
  • Acid-fast stain
  • Endspore stain
21
Q

What is the most used staining technique?

A

Differential stains

22
Q

What makes a differential stain different to simple staining?

A

Uses more than one type of dye

23
Q

Why do you use differential staining?

A

To distinguish between different structures

24
Q

What is the most frequently used differential stain?

A

Gram stain

25
Q

What is the procedure of an acid-fast stain?

A
  • Stain with carbol fuchsin with heat
  • Cooled and decolourised with hydrochloric acid
  • counterstain with methylene blue
  • Rinse with water
26
Q

Why do we use acid-fast stain?

A

Identify a subset of bacterium genes - Mycobacterium has a waxy material in cell wall

27
Q

Why do we use endospore stains?

A

To identify endospores inside of plasmids of bacteria

28
Q

Why do we have to use endospores staining techniques to identify endospores?

A

-Highly resistant to dissection, heat and radiation

29
Q

What is the procedure of an endospore stain?

A
  • Malachite green stain
  • Heat
  • Rinse with water
  • Counterstain with safranin
  • Rinse with water
  • Appears green if endospores present
30
Q

What are the different types of special stains?

A
  • Negative stains

- Flagellar stains

31
Q

Why do we use special staining procedures?

A

Interact with special features such as the capsules or flagellum

32
Q

What do negative stains do?

A

Negative stains stain the background leaving cells colourless as acid dye are repelled by negative charges on the surfaces of the cell

33
Q

What is the negative stain procedure?

A
  • Basic counterstain
  • Rinse with water
  • Eosin stain
  • Rinse with water

BIO1337 - Microbiology (18 decks)

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