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BMS 212 > Chapter 2: How We See the Invisible World Slides > Flashcards

Chapter 2: How We See the Invisible World Slides Flashcards

1
Q

What effect does the wavelength of radiation have on microscopy?

A

Shorter wavelengths have better resolution and higher magnification.

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2
Q

What causes magnification?

A

The light spreading out from the microscope.

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3
Q

What is refraction?

A

The change of light rays as it passes through one medium to another.

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4
Q

What is magnification?

A

How close the object appears.

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5
Q

What is resolution?

A

How close 2 objects can be and still look apart.

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6
Q

What are the two things that affect resolution?

A

Wavelength and numerical aperture.

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7
Q

What is numerical aperture?

A

How much light actually makes it to your eye.

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8
Q

What is contrast?

A

Differences in intensity between two objects, or an object and its background.

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9
Q

What can we do to increase contrast?

A

Staining.

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10
Q

True or False: Contrast is not important in determining resolution.

A

False.

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11
Q

How many lenses does a simple microscope contain?

A

One.

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12
Q

Who used simple microscopes to discover microorganisms?

A

Leeuwenhoek.

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13
Q

How may lenses does a compound microscope contain?

A

A series of lenses for magnification.

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14
Q

How do we determine the total magnification of a compound microscope?

A

Magnification of objective lens times the magnification of the ocular lens.

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15
Q

How does light pass through the microscope?

A

Light passes through specimen into objective lens.

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16
Q

How many ocular lenses are in a compound microscope?

A

One or two.

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17
Q

What do most compound microscopes have to direct light through a specimen?

A

Condenser lenses.

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18
Q

What does oil immersion do?

A

Reduces light scattering
Increases resolution

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19
Q

When is the use of a dark-field microscope best?

A

When observing pale objects.

20
Q

What light rays enter the objective lens?

A

Only light rays scattered by the specimen.

21
Q

How does the specimen appear in the microscope?

A

Specimen appears light against a dark background.

22
Q

Why do we use dark-field microscope?

A

Increases contrast and enables observation of more details.

23
Q

What do fluorescence microscopes do?

A

Direct UV light source at specimen.

24
Q

What does UV light increase?

A

Resolution and contrast.

25
Q

True or False: Some cells are naturally fluorescent; others must be stained.

A

True.

26
Q

Why do we use fluorescence microscopy in immunofluorescence?

A

It is used to identify pathogens and to make visible a variety of proteins.

27
Q

True or False: In fluorescence microscopy, the specimen radiates energy back as a shorter, visible wavelength.

A

False: It radiates energy back as a longer, visible wavelength.

28
Q

What do confocal microscopes do?

A

Use fluorescent dyes
Use UV lasers to illuminate fluorescent chemicals in a single plane

29
Q

What is increased with confocal microscopes?

A

Resolution is increased because emitted light passes through pinhole aperture.

30
Q

What constructs the 3D images in confocal microscopy?

A

A computer.

31
Q

What can an electron microscope see?

A

Detailed views of bacteria, viruses, internal cellular structures, molecules, and large atoms.

32
Q

What can electron microscopes do better than light microscopes?

A

They have greater resolving power and magnification.

33
Q

What are the two types of electron microscopes?

A

Transmission electron microscope (TEM)
Scanning electron microscope (SEM)

34
Q

Where does electron microscopy take place?

A

In a vacuum.

35
Q

How does a TEM work?

A

Electron beam will send electrons through the specimen against the lens, and it picks up the image.

36
Q

How does a SEM work?

A

Images are formed from electrons bounced off the specimen.

37
Q

Why do we use stains?

A

Coloring specimen with stain increases contrast and resolution.

38
Q

What is the colored portion of the dye for staining?

A

Chromophore

39
Q

What are simple stains?

A

One dye is used to create contrast.

40
Q

What are differential stains?

A

Dyes different organisms different colors.

41
Q

What are some common differential stains?

A

Gram stain
Acid-fast stain
Endospore stain
Histological stain

42
Q

What does an HE stain show?

A

Cell contents (cytoplasm, nucleus, organelles, extracellular, components).

43
Q

What are some simple stains?

A

Negative stains
Flagellar stains
Fluorescent stains

44
Q

What do stains for electron microscopy contain?

A

Chemicals containing heavy metals (gold).

45
Q

When do we use a GMS (gomori methenamine silver) stain?

A

On tissues.

BMS 212 (24 decks)

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