Observing Microorganisms Through a Microscope (chapter 3)

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1

Microorganisms are measure in

LM = > or Micrometers um (10-6 m) is equal to 0.000001m.

EM = < or Nanometers um (10-9 m)

2

A virus measures 100 nm in length. What is its length in um?

0.01 um

3
  1. lm=106 mm
  2. lm= 10 9mm
  3. lm= 1012 m
  4. lm= 10-6m
  5. lm=10-9m
  6. lpm=10-12m
  1. micro meter
  2. nano meter
  3. pico meter
4

A microorganism measures 5 um in length. Its length in mm would be

0.005 mm

5

Simple microscope consists of

One Lens

6

A compound microscope has

Multiple lenses

7

Simple staining is necessary to improve contrast in which microscope?

compound light microscope

8

The most common microscope used in microbiology is

The compound light Microscope

9

The total magnification of an object is calculated:

Multiplying the Ocular magnification X Objective magnification by the magnification of the ocular lens.

10x x 40x = Total magnification 400x

10

The compound light microscope uses

Visible Light

11

The maximum resolution, or resolving power

(ability to distinguish between two points)

Compound light microscope is 0.2 um,maximum magnification is 2000x.

12

Specimens are stained to increase the difference between

The refractive indexes of the specimen and the medium

13

Immersion oil is used with the 100x objective lens of the compound light microscope to ______.

Reduce light loss between the slide and lens

14

Brightfield illumination is used for

Used for stained smears

15

Which microscope produces an image of a light cell against a dark background; internal structures are presence of extremely small organisms.

Darkfield Microscope

16

Which of the following types of microscopy is most useful for viewing the internal structures of unstained specimens? It brings direct and reflection.

Phase Contrast Microscope

17

Which microscope provides a colored,three-dimensional image of the object being observed.

Differential Interference Contrast Microscope

18

Which microscope is used to observe a specimen that emits light when illuminated with an ultraviolet light?Allows organisms to be identified base on antigens,even if the organisms are inside a cell.

Fluorescence Microscope

19

Which microscope is used a computer to process the images,two-dimensional three- dimensional images of cells can produced.

Confocal Microscope

20

Which microscope is based on the Interpretation of sound waves through a specimen. It is used to study living cells attached to surfaces such as cancer cells,artery plaque,and biofilms.

Scanning Acoustic Microscopy

21

A student is observing an object that displays the internal detail on virus at great magnification. Which type of microscope is used for this image?

Transmission Electron Microscopy

22

A microscopist is studying the surface pores on a bacterial specimen.

Which microscope provides the best three-dimensional surface structure image?

Scanned -Probe Microscopy

23

What is the 3 lenses system in a 10 pound LM?

  1. Ocolar lenses
  2. Condenser lenses
  3. Objective lenses
24

2 Types of electron microscopes?

  1. Scanning- SEM
  2. Transmission-TEM
25

Electron Microscopes use?

A beam of electrons instead of light.

26

Preparing means coloring a microorganism with a dye to make some structures more visible.

Fixing uses heat or alcohol to kill and attach microorganism to a slide.

A smear is a thin film of material used for microscopic examination.

Bacteria are negatively charged, and the colored positive ion of a basic dye will stain bacterial cells.

The colored negative ion of an acidic dye will stain the background of a bacterial smear;a negative stain is produced.

Preparing Smears for Staining

27

What are 2 types of staining?

  1. Simple Stain
  2. Differencial
28
  1. Simple stain is an aqueous or alcohol solution of a single basic dye.
  2. It is used to make cellular shapes arrangements visible.
  3. A mordant may be used to improve bonding between the stain and the specimen.

Simple Stains

29
  1. Such as the Gram stain and acid-fast stain,differentiate bacteria according to their reactions to the stains.
  2. The Gram stain procedure uses a purple stain (crystal violet),iodine as a mordant,an alcohol decolorizer, and a red counterstain.
  3. Gram-positive bacteria retain the purple stain after the decolorization step;gram-negative bacteria do not and thus appear pink from the counterstain.
  4. Acid-fast microbes,such as members of the genera Mycobacterium and Nocardia,retain carbolfuchsin after acid-alcohol decolorization and appear blue.

Differential Stains

30

What are the 2 types of differential stains?

  1. Gram Stain ( positive,negative)
  2. Acid Fast Stain
31

Gram Positive Cell Wall is ?

Thicker than gram negative

32

What are 3 types of dyes ?

  1. Methylene (Blue)
  2. Crystal (Violet)
  3. Safrarin (Bright Red)
33

Gram Stain and Acid Fast Stain is used for ?

Identification

34

Special Structone Stain is used for?

Classification

35

What color is Gram postive?

What color is Gram negative?

Gram postive - purple

Gram negative- red

36

Gram postive is kill by?

Gram negative is?

  1. Penicillin and detergents
  2. Resistant to antibiotics
37

What two Acids do not respond to gram stain?

Mycobacterium: mycolic acid

Nocardia: mycolic acid

38

What is mordants used for?

To hold stain or coat the specimen to enlarge. (EX: Iodine)

39

What are the 3 characteristics of simple stain?

  1. Size
  2. Shape
  3. Cell arrangement
40

Staining Help?

View details of specimen with dye.

41

Special Stains

Negative staining is used to make microbial capsules visible.

The endospore stain and flagella stain are special stains that color only certain parts of bacteria.

42

What are the 3 stains of special structural stain?

  1. Endospore
  2. Capsule
  3. Flagella
43

What does endospores produce?

Toxins

44

Acid-Fast Stain Binds?

Strong only to bacteria that have waxy material in their cell walls.

45

You are performing a Gram stain on gram positive bacteria and you stop after the addition of the first dye. What is the appearance of the bacteria at this point?

purple

46

You are performing a Gram stain on gram negative bacteria and you stop after the addition of the mordant. What is the appearance of the bacteria at this point?

purple

47

You are performing a Gram stain on gram negative bacteria and you stop after the descolorizer. What is the appearance of the bacteria at this point?

colorless

48

You are performing a Gram stain on gram positive bacteria and you stop after the addition of the counterstain. What is the appearance of the bacteria at this point?

purple

49

Which type of stain is useful in helping clinicians to decide which antibiotic to prescribe for a bacterial infection?

Gram stain

50

Which step in the Gram stain is the critical step in differentiating gram positive cells from gram negative cell?

alcohol-acetone

51

Which of the following steps of the Gram stain are in correct order?

a) Crystal Violet

b) Iodine

c) Alcohol acetone

d) Safranin

52

You find colorless areas in cell in a gram stained smear. What should you apply next?

an endospore stain

53

Which microscope is used to see intracellular detail in a living cell?

two-photon microscope

54

The courterstain used in the Gram stain is a basic dye

True