Ch. 3 Observing Microbes Through The Microscope Flashcards Preview

Microbiology > Ch. 3 Observing Microbes Through The Microscope > Flashcards

Flashcards in Ch. 3 Observing Microbes Through The Microscope Deck (27):
1

mm (millimeter)

* 1 × 10^-3 m
* 1,000 of a meter

2

mcm (micrometer)

1 x 10^-6 m
1 millionth of a meter

3

nm (nanometer)

1 x 10^-9 m
1 billionth of a meter

4

What is the average size of a bacterium?

3 mcm

5

What is the highest magnification of a binocular Compound Light Microscope?

1000x

6

What magnification do you go to when observing bacteria?

Highest (1000x)

7

Bacteria are considered to be what type of cell?

Unicellular

8

When light from a microscope scatters, what does it do to your image?

• Compromises the image quality

9

What is refraction?

• Bending/scattering of light, includes air (higher the refractive index the more it bends)

10

What is the purpose of using pure mineral oil?

Causes the refractive index to lower, therefore causing less light to scatter (has a lower refractive index than air)

11

What’s resolution?

• Clarity and sharpness

12

What’s contrast?

Range of light and dark values in an image (the greater the range of light/dark values the higher the contrast)

13

Bright field

* The entire field of view is (lit up) illuminated uniformly
* Ex. paramecium
- Pellicle somewhat distinguishable
- Less distinguished between the inner and outer boarder
- Can see cilia
- Can’t observe nucleus

14

Dark field

Uses a special condenser with an opaque disk that blocks light from entering the objective lens directly.
- No cilia observed
- Vacuoles & nucleus can be seen
- Illuminated pellicle but the boarders a fuzzy
- Stain introduces and increases contrast
- Examine live microorganisms that are either invisible in the ordinary light microscope. Cannot be stained by standard methods

15

What are the different types of light illumination from the compound light microscope?

* Bright field
* Dark field
* Phase contrast

16

What are the two types of compound lens?

* Objective
- Highest magnification 100x (oil immersion lens)
- Light scatters bc it hits the small air space
- 4 diff magnification
* Ocular
- Fixed magnification @ 10x

17

What is the resolution limit?

* 0.2 mcm
* Amount of distance btwn two objects before they look like they’re touching

18

What are the two most common types of electron microscopy (EM)?

* Transmission
* Scanning

19

What color does each stain for the Gram Stain?

• Gram positive = purple
• Gram negative = pink

20

Name the two types of helminths?

• Worm & Flukes

21

What can you focus the electron beams and change their direction with?

Electromagnets

22

Where is fluorescence generated for the EM?

By the flow of electrons

23

Give examples of photosynthetic microbes?

Algae & Cyanobacteria

24

Phase Contrast

* Condenser containing an annular (ring-shaped) diaphragm
- Can observe sharpness and graininess of the internal structures of the cytoplasm
- More defined vacuoles
- Better resolution in the cytoplasm than in the dark field
Clear distinction of the inner and outer pellicle

25

What does staining introduce?

Contrast

26

Phase Contrast

* Condenser containing an annular (ring-shaped) diaphragm
- Can observe sharpness and graininess of the internal structures of the cytoplasm
- More defined vacuoles
- Better resolution in the cytoplasm than in the dark field
Clear distinction of the inner and outer pellicle

27

What does staining introduce?

Contrast