Test 1 Ch 3: Microscopes

Question 1

Metric System

Answer 1

• We use this
  1 meter/1,000,000 micrometer

Question 2

Compound light microscope naming

Answer 2

• Compound = more than 1 lens
• Light = the source of ilumination

Question 3

What is the pathway of light from the bottom of the microscope to the eye?

Answer 3

Illuminator –> condenser –> focuses light on specimen –> objective lens –> magnified by ocular lens –> eyeball

Question 4

Acidic dye

Answer 4

Negative ion has color

Question 5

Basic dye

Answer 5

Positive ion has color

Question 6

Immersion oil

Answer 6

Used for 1000x; traps and forces more light into the objective so you can see it

Question 7

Fixing

Answer 7

Prevents microbes from being washed off during staining; kills microbes :(

Question 8

Resolution

Answer 8

ability of a lens to distinguish 2 points that are a specific distance apart

Question 9

How do you calculate total magnification?

Answer 9

multiply: objective lens magnification and ocular lens magnification

Question 10

Basic dyes

Answer 10

The positive ion has color (chromophore)

Question 11

Acidic dyes

Answer 11

The negative ion has color

Question 12

What type of dye do you use to stain bacteria? (acidic or basic)

Answer 12

Basic

Bacteria has a slightly negative charge (pH is 7); positives and negatives attract

Question 13

Simple stain

Answer 13

Uses one basic dye so that the specimen has color and the background is white

Question 14

Negative stain

Answer 14

Uses one acidic dye so that the specimen is white, and the background has color

Question 15

What 3 things do simple and negative stains tell you?

Answer 15

1. Size
2. Morphology (shape)
3. Arrangement (position of cells in relation to each other)

Question 16

What are differential stains used for?

Answer 16

Used to differentiate bacteria based on other characteristics other than what a simple or negative stain tells you

Question 17

What are the 2 types of differential stains?

Answer 17

1. Gram stain
2. Acid-fast stain

Question 18

What is a gram stain?

Answer 18

• Created by Hans Christian Gram
• Divides bacteria into 2 groups: gram positive and gram negative, which are based on what color the cells end up

Question 19

What is the first step in a gram stain and what color is the specimen?

Answer 19

• Dye: Crystal violet
• Purple

Question 20

What is the second step in a gram stain and what color is the specimen?

Answer 20

• Chemical: iodine
• Color: purple
• Acts as a mordant –> enhances the stain
• All cells take up iodine and the purple cells stay purple

Question 21

What is the third step in a gram stain and what color is the specimen?

Answer 21

• Chemical: Decolorizer (alcohol)
• Gram positive cells stay purple, gram negative cells are colorless

Question 22

What is the fourth step in a gram stain and what color is the specimen?

Answer 22

• Chemical: dye called safranin
• Color: reddish/pink
• Gram positive cells are purple, gram negative cells are reddish/pink

Question 23

What is an acid fast stain?

Answer 23

• Type of differential stain
• Binds with bacteria that have a waxy cell wall
• Myobacterium (Leprosy, TB)
• Fushia dye, decolorizer, counterstained blue
• Decolorizer: acid alcohol

Question 24

What is a structural stain?

Answer 24

A stain that shows the presence or absence of specific structures that the bacterium may have

Question 25

What are the 3 examples of structural stains?

Answer 25

- Capsule staining - Endospore staining - Flagella staining

Question 26

What does brightfield microscopy use?

Answer 26

Light

Question 27

What is dark field microscopy?

Answer 27

- Direct light is blocked - Specimen is lit up - Used to examine specimens that are unstainable or distorted by staining

Question 28

What is phase-contrast microscopy?

Answer 28

- Detailed examination of living organisms - Combines dark and bright field microscopy - Gets a 3D image

Question 29

What is differential interference microscopy (DIC)

Answer 29

Similar to phase-contrast but has 2 light sources and prisms (color contrast)

Question 30

What is fluorescence microscopy?

Answer 30

- Uses UV light - Can use to differentiate between T and B cells - uses fluorochromes

Question 31

What is fluorescence microscopy?

Answer 31

- Uses UV light - Has properties of fluorescence - One plane of a specimen is illuminated at a time - Computer reconstructs into 3D image

Question 32

What is scanning acoustic microscopy (SAM)?

Answer 32

- Scanning = reflecting off specimen - Acoustic = sound waves instead of light - Works similar to ultrasounds

Question 33

What are 2 types of electron microscopy?

Answer 33

Transmission electron microscopy (TEM) and scanning electron microscopy (SEM)

Question 34

What is electron microscopy? ($$$)

Answer 34

- Uses beam of electrons instead of light - Electrons allow to see more detail because it has a smaller wavelength than that of light - Greater resolution, greater magnification, greater cost

Question 35

What is transmission electron microscopy (TEM)

Answer 35

- Transmission = what you use for illumination passes through the specimen - Electrons pass through specimen - Specimens must be super thin - 0.2 nm resolution; 10,000-100,000x magnification

Question 36

What is scanning electron microscopy? (SEM)

Answer 36

- Electrons are directed over the surface of the electron - Good for cell surface structures - 3D appearance - Lower quality than TEM - 0.5 nm resolution; 1,000-500,000x magnification