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MBIO 1010 > Microscopy and Microorganism Staining > Flashcards

Microscopy and Microorganism Staining Flashcards

Lectures 5-15

1
Q

What are the 4 types of light microscopy?

A
  1. Bright Field
  2. Phase-Contrast
  3. Dark-Field
  4. Fluorescence
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2
Q

What is the magnification of an objective lense?

A

10x-100x magnification

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3
Q

What is the magnification of an ocular lense?

A

10x-20x magnification

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4
Q

How do you get total magnification?

A

Objective magnification x ocular magnification

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5
Q

What is the definition of magnification?

A

The ability to make an object larger.

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6
Q

What is the definition of resolution?

A

the ability to distinguish two adjacent objects as

separate and distinct.

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7
Q

What is the limit of resolution for a light microscope?

A

0.2 μm

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8
Q

True or false: when wavelength increases, resolution increases.

A

False: when wavelength increases resolution decreases.

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9
Q

True or false: light must pass through two points for them to be viewed as separate objects.

A

True

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10
Q

What is simple staining?

A

One dye used to colour specimen.

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11
Q

What is the coloured portion of staining dye called?

A

Chromophore

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12
Q

What are the two types of simple staining dye? What are their charges?

A

Basic dye- positively charged chromophore

Acidic dye- negatively charged chromophore

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13
Q

What does basic dye bind to?

A

The negatively charged molecules on a cells surface.

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14
Q

What does acidic dye bind to?

A

Acidic dye does not bind to anything, it’s repelled by the cells surface. It stain the background as a “negative” stain.

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15
Q

Give an example of a basic dye and acidic dye.

A

Basic: crystal violet
Acidic: nigrosin

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16
Q

Give the five steps of staining.

A

1.Prepare smear
2. Air fry
3 Heat fix
4. Flush with stain
5. Examine under microscope

17
Q

What is a differential stain?

A

Stain which separates bacteria into two groups.

18
Q

What type of staining is a gram stain? What does it do?

A

Differential stain- separates bacteria into two groups based on cell wall structure.

19
Q

What are the two types of gram bacteria? What colour are they?

A

Gram positive- retain primary stain (purple)

Gram negative- lose primary stain and takes the counter stain colour (red/pink)

20
Q

What type of stain is an acid fast stain? What does it to?

A

Differential stain- detects mycolic acid in the cell wall of the genus Mycobacterium.

21
Q

The two colours of an acid fast stain are fuchsia and blue. What does each colour mean?

A

Fuchsia- Mycobacterium that retains primary stain

Blue- anything else on the slide (counter stain)

22
Q

Another differential stain is an endoscope stain. What are the colours, and what do they represent?

A

Green: endospores that retain primary stain.
Pink: Cells counterstained

23
Q

Give an example of a bacteria that would undergo endospore stain.

A

Bacillus anthracis

24
Q

What is phase-contrast microscopy?

A

A type of light microscopy. Phase ring amplifies differences in the refractive index of cell and surroundings.

25
Q

What is a benefit to phase-contrast microscopy?

A

Can view live samples

26
Q

What is dark-field microscopy?

A

A type of light microscopy where specimen are illuminated by a hollow cone of light. Only refracted light enters the object.

27
Q

What is one reason we use dark-field microscopy? Give an example of a bacteria that requires it.

A

Used to observe specimen that don’t stain well.

Example: Treponema pallidum (syphilis)

28
Q

What is fluorescence microscopy?

A

A type of microscopy that visualizes bacteria that fluoresce. The bacteria emit light of one colour when illuminated with another colour of light.

29
Q

What is differential interference contract (DIC) microscopy used for? How does it work?

A

Used to image cells in three dimensions. Polarizer creates two distinct beams of polarized light which give structures such as endospores, vacuoles, and granitas a 3-D structure.

30
Q

What type of microscopy is Confocal scanning laser microscopy (CSLM)? How does it work?

A

Three dimensional microscopy- uses a computerized microscope and lasers to generate a 3-D image by layering multiple images.

31
Q

What is the resolution of CSLM?

A

0.1 um

32
Q

Electron microscopes use electrons instead of photons to view cells. Why is the resolution higher?

A

Electrons have a shorter wavelength then light.

33
Q

What are the two types of electron microscopes?

A

Transmission electron microscopes (TEM) and Scanning electron microscopes (SEM)

34
Q

What is the magnification and resolution of TEM? How thin must the specimen be?

A

Magnification and resolution: 0.2 nm

Cells must be 20-60 nm thin

35
Q

What must be done to a specimen before it undergoes TEM?

A

Must be stained with metals like lead or uranium.

36
Q

What must specimen do before undergoing SEM?

A

Be coated with a thin film of heavy metal (e.g., gold)

MBIO 1010 (14 decks)

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