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Microbiology T2 > Test 2 > Flashcards

Test 2 Flashcards

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1
Q

Size of lens aperture

A

As the magnification increases, the aperture size of the lenses decreases. Resolution is higher, more details will be revealed.

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2
Q

Working Distance

A

The space between the objective lens and the slide/specimen/stage.

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3
Q

Length of the body tube

A

160mm (16cm)

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4
Q

Body Tube Length

A

Body tubes transmits image from objective to ocular. Longer the tube, increase in magnification.

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5
Q

Refraction

A

The ability of transparent media to bend light and in the process alter the appearance of the image formed by light.

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6
Q

Refractive Index

A

Different materials have different degrees of refraction. Compares how much each material alters the appearance of light.

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7
Q

Relationship in refractive index

A

The higher the refractive index, the stronger the refraction.

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8
Q

What is the effect/benefit of Immersion oil on refraction?

A
  • Removes air from the working distance
  • Makes refractive indexes appear more even
  • Enables the lens to trap previously refracted light
  • Allows the image to fit within the aperture of the lens
  • Focusses the final image better
  • Achieves a higher image resolution
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9
Q

Bright Filed Microscope: Design and Image

A

It is typically binocular with a condenser, Objective, and Ocular Lenses. It shows an image of a specimen by contrasting it against a brightly-lit background, which can be fine-tuned with an Iris-Diaphragm.

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10
Q

Darkfield Microscope : Design and Image

A

Compound Light Microscope that uses an opaque disc to limit transmission of light through the condenser. The resulting dark background creates adequate contrast; transmitted light is reflected off the surface of unstained, transparent, live specimens that appear to glow in the dark.

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11
Q

PHASE CONTRAST MICROSCOPY

a. Explain how it works
b. Determine how it is designed differently from other Microscopes
c. Describe appearance of the image formed

A

a. Has an Annular Diaphragm that breaks a single beam of light into multiple rays of light shades to highlight details of structure.
b. The Objective Lens has a Phase Ring (or Diffraction Plate) that creates several phases and shades from a single light beam.
c. This produces high final image definition and contrast without staining.

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12
Q

DIFFERENTIAL INTERFERENCE CONTRAST MICROSCOPY

a. Explain how it works
b. Determine how it is designed differently from other Microscopes
c. Describe appearance of the image formed

A

a. The two light beams pass through a special condenser. No staining is required; however, a special condenser splits the beam of light with a prism and the individual light rays travel at different speeds that is transmitted as different colors. This ‘rainbow effect’ floods the specimen with colored-light that produces a brightly-colored image. Another prism in the objective lens maintains the color of the image.
b. It uses two light beams to form the final image.
c. The two light beams create a 3-D image, the prisms add color, and the lenses produce depth and high resolution.

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13
Q

FLUORESCENCE MICROSCOPY

a. Explain how it works and describe its final image

A

a. uses the short wavelength of (UV) light to form an image. Images formed are not visible without a special dye called Fluorochrome that makes them glow in UV-light. It is especially valuable for observing positive reactions between antibodies and antigens: the fluorescent dye binds to antibodies and makes a positive reaction visible by attracting billions of glowing antibodies to surface antigens. In a negative result, antibodies, which are only about 15 nm, will not be visible or glow.

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14
Q

How wavelength and Resolution are related

A

The speed is expressed as wavelength, which is measured in (nm). In general, resolution is higher at shorter wavelengths. Although better image quality is produced if light is manipulated properly, the highest useful magnification of a light microscope is about 2,000X. At this magnification, resolution is limited to 200 nanometers (nm) and viruses are not visible.

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15
Q

Determine how fluorescent microscopy is designed differently from other Microscopes

A

Images formed are not visible without a special dye called Fluorochrome that makes them glow in UV-light.

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16
Q

Differentiate Fluorochrome and Chromophore

A

chromophore is chemistry thats part of the molecule of a dye responsible for its color, while fluorophore is biochemistry molecule or functional group which is capable of fluorescence.

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17
Q

. ELECTRON MICROSCOPY

a. Explain how it works

A

Electron Microscope uses electrons for illumination because they have shorter wavelength and yield higher resolution than light. The better resolution permits higher useful magnification that reveals more details. However, electrons are 100,000 times beyond the range of visible light. Therefore, the final electro-micrograph image is not brightly-colored; instead, it shows shades between black and white, like an x-ray image. These shades of grey are assigned different colors artificially to highlight their diversity.

18
Q

. ELECTRON MICROSCOPY

b. Identify parts and functions

A

The Electron Microscope transmits the Electro-Micrograph through the tube and spreads the electron image using an Electromagnetic Objective Lens, resulting in magnification. The Electro-Magnetic Projector Lens re-magnifies the image, just like the Ocular Lens, projecting it to an Electron-sensitive screen. The electrons imprint a magnified image of the specimen on a Fluorescent screen, viewable with an Eyepiece. Since two sets of lenses magnify the final image, an Electron Microscope meets the criteria for a Compound Microscope.

19
Q

. ELECTRON MICROSCOPY

c. Describe image formation and view

A

The illuminator of the Electron Microscope is located at the top unlike the Light Microscope, where it is below. Electrons are accelerated down the air-tight tube from the electron source and focused on the specimen by an Electro-Magnetic Condenser. When the electrons interact with the specimen, and Electron image or Electro-Micrograph is formed.

20
Q

. ELECTRON MICROSCOPY

d. Determine how magnification and illumination occur

A

Uses Electro-Magnetic Fields. Glass lenses cannot be used in an Electron Microscope because electrons do not penetrate them very well. Therefore, Electron Microscopes operate under vacuum and samples must literally be “thinner than air” for proper processing.

The illuminator of the Electron Microscope is located at the top. Electrons are accelerated down the air-tight tube from the electron source and focused on the specimen by an Electro-Magnetic Condenser. When the electrons interact with the specimen, and Electron image or Electro-Micrograph is formed.

21
Q

. ELECTRON MICROSCOPY

e. Compare and contrast the two types

A
  1. The Electron Microscope transmits the Electro-Micrograph through the tube and spreads the electron image using an 2.Electromagnetic Objective Lens, resulting in magnification.
  2. The Electro-Magnetic Projector Lens re-magnifies the image, just like the Ocular Lens, projecting it to an Electron-sensitive screen.
  3. The electrons imprint a magnified image of the specimen on a Fluorescent screen, view able with an Eyepiece.
  4. Since two sets of lenses magnify the final image, an Electron Microscope meets the criteria for a Compound Microscope.
22
Q

RESOLUTION: Compare limits of Resolution for:

a. Human Eye (Normal vision)
b. Light Microscope (LM)
c. Scanning Electron Microscope (SEM)
d. Transmission Electron Microscope (TEM)

A

a. Human Eye (Normal vision)- (200 um) Micrometers
b. Light Microscope (LM)- (200 nm)
c. Scanning Electron Microscope (SEM)- (10 nm)
d. Transmission Electron Microscope (TEM)- ( 10 pm)

23
Q

DYES, STAINS, & MICROSCOPY

a. Recall what a dye is, how it is formed, and origin of its color

A

Dyes are permanently-colored organic salts that imprint their colors on biological materials like cells or microbes. Like every salt, including table salt, a dye is formed when an acid reacts with a base; therefore, the two ions of a salt come from an acid and a base. The Positively-charged Cation (+) and Negatively-charged Anion (–) have opposite charges that attract and react with each other to form new compounds.

24
Q

DYES, STAINS, & MICROSCOPY

b. Describe the reaction that forms a salt or dye

A

The Anion from the Acid and the Cation from the Base form a SALT. Left-over ions that did not form a salt, become Water. A SALT can only be a dye if any of its ions has color-“Chromophore”. A dye may acquire color from a colored Cation (+), colored Anion (-), or both ions.

25
Q

DYES, STAINS, & MICROSCOPY

c. Determine the fate of all ions in Acid-Base reactions

A

The Anion from the Acid and the Cation from the Base form a SALT. Left-over ions that did not form a salt, become Water. These are always the two products of Acid-Base reactions. A SALT can only be a dye if any of its ions has color. The colored ion of a dye is a Chromophore. A dye may acquire color from a colored Cation (+), colored Anion (-), or both ions

26
Q

. DYES, STAINS, & MICROSCOPY

d. Compare Negative and Direct/Positive Staining

A

The cells of microbes tend to have a net negative charge, as is the case with human, animal, or plant cells. This draws the opposite charges of the Cations from the Dye into the negatively-charged cell. If the Cation has color, the cell becomes stained. Rinsing removes the stain from the slide and background but the smear retains color, resulting in Direct or Positive Staining. Basic dyes are used for direct staining of the bacterial smears, leaving the background clear. Microbiology uses Basic dyes for 90% of staining procedures.

Some bacterial structures are, however, best seen if they remain clear. In this case, the cation, which is attracted to the cell, should not have color but the anion should, so that its chromophore can stain the background; this is Negative staining.

27
Q
  1. DYES, STAINS, & MICROSCOPY

e. Explain interaction between dyes and cells

A

Staining simply adds color to a cell so that it contrasts with its background.
Dyes are permanently-colored organic salts that imprint their colors on biological materials like cells or microbes.

28
Q

CHEMICAL GROUPS OF DYES

a. Name some dyes and their Chemical Groups

A
  • Methylene Blue
  • Safranin
  • Crystal Violet
  • Malachite Green
  • Carbol Fuchsin
    BASIC dyes are used a lot, ACIDIC dyes are used less, and NEUTRAL dyes are rarely ever used.
29
Q

CHEMICAL GROUPS OF DYES

b. Determine how each group is used

A

BASIC dyes are used a lot
ACIDIC dyes are used less
NEUTRAL dyes are rarely ever used.

30
Q

CHEMICAL GROUPS OF DYES

c. Define Simple Staining, the steps, and results

A

SIMPLE STAINING
Like a simple microscope, Simple Staining uses just one dye: by default, a basic dye is used, because it highlights the specimen with color in contrast to a clear background.

PROCEDURE
Make a smear of the specimen on a glass slide.
Air-dry the smear on the slide
Heat-Fix
Stain heat-fixed smear with a Single dye, like Methylene Blue or Safranin (1 min)
Rinse-off excess dye in the background with water.
Dry Slide and viewed with oil-immersion lens.

Simple staining shows the colored specimen against a clear background. Regardless of how many types of bacteria are present, Simple Staining colors them alike with a single dye. Therefore, Simple staining is not a decision-making technique. Rather, the procedure is useful for comparing cells by physical characteristics like
shape, size, arrangement, and texture.

31
Q

CHEMICAL GROUPS OF DYES

d. Describe how samples are prepared for staining

A

Therefore, it is spread thin on a transparent glass slide as a Smear. Since stains are liquids, there is always a risk that they could wash away the specimen. Therefore, the smear is air-dried before staining. Just before staining, the dried smear is fixed using a physical fixing agent, like heat, by rapidly passing it over open flame. Fixing secures the smear to the slide, prevents loss of specimen, and preserves its structure.

32
Q

CELLS AND KINGDOMS

a. Review history and Scientists linked to Cells, Microscopy, and Stains

A

*van Leuwenhoek- 1673
“First one to ever see a cell, because they were moving, called them animalcules. Discovered microorganism “Father of Microorganisms” Invented first microscope.”
*Robert Hook- 1665
“Built the first compound microscope. Saw back of a tree specimen and was able to identify a cell wall. Bunged together. “
*Matthias Schleiden-1838
“First one to conclude that all plants are made of cells.”
*Theodor Schwann- 1839
“Sliced the tissue/animal ect. and every slide of tissue was made of cells. Development of the cell theory.”
*Hans Christian Joachim Gram- 1884
“The Gram stain is the most important staining procedure in Microbiology. “

33
Q

Cell theory

A

All living things are made of cells. Theodor Schwann 1839

34
Q

CELLS AND KINGDOMS

b. Name major Cell types, Platforms, and compare their sizes

A

Cell type: Platforms: Sizes:
Prokaryotes 1 0.2-2.0 um
Eukaryotes: 10-100um
Human/animal 2
Plant/ Algea 3

35
Q

CELLS AND KINGDOMS

c. Compare characteristics of Cells
Contrast

A 
Common to all 3: 
Cytoplasm
Plasma Membrane
Robosomes
Nucleic Acid: 
DNA,RNA

Contrast:
Plant: Animal Cell:
1. Cell Wall 1. No Cell Wall
2. Vacuole 2. Lysosomes
3.Chloroplast 3.Centrioles
4.Basal Body/Flagella/ Cilia

36
Q

CELLS AND KINGDOMS

d. List the Kingdoms and identify the Cell Platform for each.

A

Kingdoms: Prokaryotic: Euka-Animal: Euka-Plant:
Archaea √ X X
Eubacteria √ X X
Protista X √ √
Fungi X X √
Plantae X X √
Animalia X √ X

37
Q

CELLS AND KINGDOMS

e. How are cells in one Kingdom unique or different from others?

A

Protista is the only kingdom that is both animal and plant !

38
Q

CELLS AND KINGDOMS

f. How many Kingdoms are Prokaryotic, Eukaryotic, Unicellular, or Multi-cellular?

A

Kingdom Structure
Prokaryotes:-
Bacteria Unicellular
Archaea Unicellular

Eukaryotes:-
Protista		Unicellular	
Fungi		Unicellular or Multicellular	
Animalia		Multicellular	
Plantae		Multicellular
39
Q

Transmission Electron Microscopy vs. Scanning Electron Microscopy

A

Transmission Electron Microscopy, the specimen for electron microscopy is almost as thin as air, allowing the electrons to transmit the image as a 2- dimensional, high resolution, electro-micrograph.
Scanning Electron Microscopy also requires a very thin specimen but the electromagnetic lenses are not diffentiated but help to accelerate primary electrons through the tube to interact with the specimen and produce a scan of the sample by emitting secondary electrons from the surface of the specimen, which are analyzed in an Electron Collector that projects the image on a video screen. This final Scannning electro-micrograph (SEM) looks 3-dimensional

40
Q

Microscope parts and function:

A

Eyepiece: The lens the viewer looks through to see the specimen. The eyepiece usually contains a 10X or 15X power lens.
Body tube (Head): The body tube connects the eyepiece to the objective lenses.
Arm: The arm connects the body tube to the base of the microscope.
Coarse adjustment: Brings the specimen into general focus.
Fine adjustment: Fine tunes the focus and increases the detail of the specimen.
Nosepiece: A rotating turret that houses the objective lenses. The viewer spins the nosepiece to select different objective lenses.
Objective lenses: One of the most important parts of a compound microscope, as they are the lenses closest to the specimen.A standard microscope has three, four, or five objective lenses that range in power from 4X to 100X. When focusing the microscope, be careful that the objective lens doesn’t touch the slide, as it could break the slide and destroy the specimen.
Stage: The flat platform where the slide is placed.
Stage Control: These knobs move the stage left and right or up and down.
Aperture: The hole in the middle of the stage that allows light from the illuminator to reach the specimen.
Iris diaphragm: Adjusts the amount of light that reaches the specimen.
Condenser: Gathers and focuses light from the illuminator onto the specimen being viewed.

41
Q

Prokaryotes

A

lack a cell nucleus: two domains, bacteria and archaea.
Bacteria:They lack a nucleus and other membrane-bound organelles, and can function and reproduce as individual cells, but often aggregate in multicellular colonies
Archaea: are also single-celled organisms that lack nuclei.

42
Q

Eukaryotes

A

:contain organelles such as the cell nucleus, the Golgi apparatus and mitochondria in their cells
Protists: multicellular, and slime molds have unique life cycles that involve switching between unicellular, colonial, and multicellular forms.
Animals: multicellular but at least one animal group, include: dust mites, spider mites. ect
Fungi:(mushroom, large growth of fungis nasty looking) unicellular species, such as baker’s yeast, candida albicans.
Plants: (green chained, round fuzzy green splots) green algae are a large group of photosynthetic eukaryotes that include many microscopic organisms.

Microbiology T2 (1 decks)

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