Viewing Bacterial Cells

Question 1

List 7 types of microscopes

Answer 1

1) compound
2) inverted
3) phase contrast
4) confocal
5) fluorescence
6) Electron (TEM & SEM)
7) Scanning probe ( SPM & STM)

Question 2

Bright Field Microscopy

Answer 2

renders dark image against a lighter background

Question 3

Dark Field Microscopy

Answer 3

increases contrast, renders brighter image against darker background

Question 4

What are the 3 important parameters of microscopy

Answer 4

1) magnification
2) resolution
3) contrast

Question 5

Total magnification=

Answer 5

Objective Magnification x Ocular Magnification

Question 6

What is Resolution

Answer 6

ability to distinguish to points that are close together or
clarity in image

Question 7

What is contrast?

Answer 7

difference between object and its background
or difference in intensity between 2 objects

Question 8

What is Magnification?

Answer 8

ratio of image to its real size

Question 9

what is path of light for a compound microscope?

Answer 9

illuminator-condenser lenses-specimen-objective lens-body-prism that separates light into ocular lens- line of vision

Question 10

What does the addition of immersion oil do when using compound light microscope?

Answer 10

increases magnification and resolution

Question 11

How does immersion oil work

Answer 11

light bends as it enter glass and as it leaves it into air. some of that scattered light does not go into objective lens. with immersion oil light travels at same speed of glass and does not refract which allows more light to enter objective lens

Question 12

what is dark field microscope best used for?

Answer 12

live or unstained biological samples or single cell organism

Question 13

What is a darkfield stop?

Answer 13

opaque light stop that is inserted into bright field microscope which is used to create a darkfield image

Question 14

how does a darkfield stop work?

Answer 14

it blocks light traveling from the illuminator to the objective lens which allows only light that was reflected off sample to reach eye

Question 15

How are the pieces placed in an inverted microscope?

Answer 15

inverted position compared to regular compound

Question 16

What is an inverted microscope used for

Answer 16

viewing of biological material in tissue culture or petri dish
living cells or organism in more natural environment

Question 17

How does Phase microscope work?

Answer 17

uses phase contrast in specimen to create high resolution images w/o staining

Question 18

What are Phase Microscopes best used for?

Answer 18

viewing live unstained specimens and structures (i.e endospores and organelles)

Question 19

how does fluorescence microscopy work

Answer 19

uses UV light to fluoresce objects. contrast is imporved

Question 20

how does fluorescence microscopy work

Answer 20

uses UV light to fluoresce objects. contrast is improved

Question 21

What is fluorescence microscopy best used for

Answer 21

1) ID Pathogens
2) distinguish between dead/living cells
3) find particular species
4) find location of specific molecule w/in a cell
5) immunofluorescence

Question 22

How does direct immunofluorescence work

Answer 22

stain is absorbed by primary antibody which binds to antigen

Question 23

How does indirect immunofluorescence work?

Answer 23

stain absorbed by 2ndary antibody which binds to primary antibody which in turns binds to antigen

Question 24

How does a Confocal microscope work?

Answer 24

users laser to scan multiple Z-planes to produce multiple 2D images that can be constructed in 3D image

Question 25

What are confocal microscopes best used for

Answer 25

viewing thick specimens i.e biofilms

Question 26

How does Electron microscope works

Answer 26

uses electron beams focused with magnets to produce image

Question 27

List 2 types of Electron Microscope

Answer 27

Transmission Electron Microscope Scanning Electron Microscope

Question 28

How does the Transmission Electron Microscope (TEM) work and what is it best used for

Answer 28

uses electron beam that passes through specimen to see small images best used to see small/thin specimens and subcellular structures

Question 29

How does the Scanning Electron Microscope (SEM) work and what is it best used for

Answer 29

uses electron beam to visualize surfaces best used to observe 3D surface detail of specimens

Question 30

What is an ultramicrotome

Answer 30

machine that slices specimen into thin slices

Question 31

how does a scanning electron microscope work

Answer 31

uses sharp probes that are passed over surface of specimen and interact directly with it

Question 32

scanning electron microscopes can produce magnification up to...

Answer 32

100,000,000x

Question 33

what are the 2 types of scanning electron microscopes

Answer 33

Scanning Tunneling Microscope (STM) Atomic Force Microscope (AFM)

Question 34

Why do microorganisms need to be stained

Answer 34

they need to be stained in order to increase visibility and accentuate specific morphological features

Question 35

Define a Dye and its composition

Answer 35

its organic contains Benzene ring + chromophore + auxochrome group

Question 36

In a dye, what is Chromgen composed of?

Answer 36

Benzene ring + Chromophore

Question 37

In a Dye, what is the Benzene ring

Answer 37

Organic, colorless substance

Question 38

In a Dye what is. Chromophore

Answer 38

chemical that imparts color to Benzene (the coloring compound)

Question 39

In a Dye, what is Auxochrome?

Answer 39

the ionization agent. allows salt to form to bind to tissues and fibre

Question 40

list the 4 types of dye classification

Answer 40

Origin Purpose Activity Based on charge

Question 41

list the types of origin dyes (2)

Answer 41

1) naturual 2) Synthetic

Question 42

List the types of dyes based on their purpose

Answer 42

1) direct 2) indirect 3) selective 4) differential

Question 43

List type of dye-based on staining activity

Answer 43

1) nuclear 2) cytoplasmic 3) Histological

Question 44

List dye types based on charge

Answer 44

1) Acid (-) 2) base (+) 3) Salts of acid and base

Question 45

what is a Mordant

Answer 45

substance that forms insoluble compound w/stain to help fix color on cell

Question 46

Explain purpose for Schaeffer-Fulton stain and whats it used for

Answer 46

* Used for endospore staining * primary dye that is used is Melachite Green, then heat so it can fix dye so it acts like a mordant. 2ndary dye safranin that dyes pink or red