Microscopy and Staining

Question 1

What is magnification?

Answer 1

The capacity of a microscope to enlarge an image uising the lenses in the microscope.

Question 2

What is resolution?

Answer 2

It allows to distinguish between two adjacent objects and separate them into two objects.

Question 3

What is resolution limit?

Answer 3

The limit depends on the numerical aperture. It is highly dependent on light and power.

Question 4

What is contrast?

Answer 4

It allows to differentiate between the cell and surroundings in absorbing or scattering light.

Question 5

Oragnisms are (blank) so there is a need to create (blank).

Answer 5

tranpsarent, contrast

Question 6

How is contrast achieved?

Answer 6

Through various stains and dyes

Question 7

This microscope uses illumination from visible light.

Answer 7

Bright Field Microscope

Question 8

Light in BFM may come from (blank) or (blank).

Answer 8

external, microscope

Question 9

How do we see images in BFM?

Answer 9

Light source concentrates light into the condenser, projecting it to the objective lens

Question 10

How does the condenser work in Dark Field Microscope?

Answer 10

Condenser prevents light from passing through. Light is directed to the sides of the specimen.

Question 11

What is the Dark Field Microscope used for?

Answer 11

To observe motility

Question 12

Phase Contrast Microscope relies on?

Answer 12

The refractive indices of cells (ability of cells to alter the speed of light) and the background

Question 13

True or false. Cells have unique refractive indices, resulting to different brightness.

Answer 13

True

Question 14

How does Phase Contrast Microscope work?

Answer 14

Amplified by the phase ring in the condenser

Question 15

What is Phase Contrast Microscope used for?

Answer 15

Used for living organisms that cannot be stained

Question 16

The Nomarski Microscope is also called?

Answer 16

Differential Interference Contrast [DIC]

Question 17

This microscope uses a polarizer in the condenser to produce polarized light.

Answer 17

Nomarski

Question 18

In Nomarski, light passes through a (blank) generating (blank) with different refractive indices.

Answer 18

prism, 2 beams

Question 19

How does Nomarski work?

Answer 19

Light interfere w/ one another, creating a 3D optical effect, enhancing the subtle differences in cell structures

Question 20

True or false. Nomarski cannot show internal cell structures and is used to observe motility.

Answer 20

False. Nomarski is used for unstained cells, revealing internal cell structures invisible by BFM without staining.

Question 21

Fluorescence Microscope uses (blank) that can activate fluorescence molecules in cells.

Answer 21

UV light

Question 22

Example of naturally occuring activated fluorescence

Answer 22

chlorophylls

Question 23

Examples of stain that can activate fluorescence?

Answer 23

fluorochromes, DAPI

Question 24

How does Fluorescence Microscope work?

Answer 24

Filters eliminate other wavelengths of light other than the fluorescent light

Question 25

What is the use of Fluorescence Microscope?

Answer 25

Visualizing certain cell structures

Question 26

Computer assembles multiple layers to create a single high-resolution, 3D image.

Answer 26

Confocal Scanning Laser

Question 27

Best for thick specimens.

Answer 27

Confocal Scanning Laser

Question 28

In Confocal Scanning Laser, dead cells are stained (blank) and viable are stained (blank).

Answer 28

red, green

Question 29

Electron microscopy uses (blank) as lenses.

Answer 29

electromagnets

Question 30

Electron microscope is opened in a (blank).

Answer 30

vaccum

Question 31

* allows you to visualize the internal cell structures * magnification up to 500,000x | proteins & nucleic acids are visible

Answer 31

Transmission Electron Microscope

Question 32

Samples in TEM are stained using (blank) with (blank) to improve contrast. | shadow-casted

Answer 32

atom, high atomic weights

Question 33

- used to visualize external structures or surfaces of the cell - magnification up to 100,000x

Answer 33

Scanning Electron Microscope

Question 34

Specimen in SEM is usually coated in (blank).

Answer 34

thin sheet of heavy metal

Question 35

How does SEM work?

Answer 35

Electron beams scan the surface then direct it back to the computer

Question 36

Tiny stylus positioned extremely close to the specimen surface

Answer 36

Atomic Force Microscopy

Question 37

Which microscope can be used at the surface of live specimens?

Answer 37

Atomic Force Microscopy

Question 38

Wet mounts don't need to be stained with dyes. What is used to see the specimen?

Answer 38

hay infusion, pond water

Question 39

Addition of (blank) can create a viscous environment to slow down movement.

Answer 39

carboxymethylcellulose

Question 40

If carboxymethylcellulose is not avaiable, what can we use to create "tents" to trap organisms incone area?

Answer 40

cotton fiber

Question 41

True or false. E. coli is motile.

Answer 41

True

Question 42

What will the cell arrangement look like if you smeared too much?

Answer 42

Cell arrangement won’t be too visible | cells will be on top of each other

Question 43

What will the cell arrangement look like if your smear is too thin?

Answer 43

Arrangement will be scattered everywhere

Question 44

Examples of positively charged dyes:

Answer 44

crystal violet, methylene blue, safranin

Question 45

Why do we need to heat fix?

Answer 45

To attach bacteria on slide

Question 46

True or false. Positive staining include acidic dyes.

Answer 46

False. Positive staining dyes are basic/cationic. | methylene blue, crystal violet, safranin

Question 47

Example of acidic dyes:

Answer 47

nigrosine black, India ink, and Congo red

Question 48

True or false. We need to heat fix everytime.

Answer 48

False. No need for heat fixing if dye is negative. | Organisms are heat-sensitive

Question 49

Three different types of staining:

Answer 49

simple, structural, differential

Question 50

Highlights certain structures of the cell

Answer 50

structural staining

Question 51

Schaeffer-Fulton Method is also called?

Answer 51

Endospore staining

Question 52

Primary stain for endospore staining

Answer 52

Malachite green

Question 53

Endospore wall becomes permeable to malachite green due to (blank).

Answer 53

steaming

Question 54

Gram staining differentiate betwen (blank) and (blank).

Answer 54

positive, negative

Question 55

Acid fast staining is also called?

Answer 55

Ziehl-neelsen Stain Method

Question 56

You can see the presence of (blank) in Ziehl-neelsen Stain Method

Answer 56

mycolic acids | retains primary stain: carbolfuchsin

Question 57

Primary stain for Ziehl-Neelsen

Answer 57

carbolfuchsin

Question 58

Counter stain of Ziehl-Neelsen

Answer 58

methylene blue