Lecture 2

Question 1

name the 5 types of light microscopes

Answer 1

bright field
dark field
phase contrast
flourescence
differential interference contrast

Question 2

how many occular lenses can a bright field microscope have?

Answer 2

one

Question 3

occular lenses come in these 4 sizes

Answer 3

5x
10x
15x
20x

Question 4

how many objective lenses can a bright field microscope have?

Answer 4

as many as available

Question 5

objective lenses come in which sizes?

Answer 5

4x
10x
40x
100x

Question 6

which objective power is used for scanning? which is used for oil immersion?

Answer 6

4x

100x

Question 7

what is necessary for an organism to be seen under a bright field microscope?

Answer 7

high contrast

Question 8

how can you make an organism easier to see under a bright field microscope?

Answer 8

staining

Question 9

how do you calculate the total magnification?

Answer 9

ocular lens multiplied by the objective lens

Question 10

what is numerical aperture (NA)?

Answer 10

it tells you how much light bends

Question 11

how can a clearer image be achieve?

Answer 11

use a lower resultion/increase the numerical aperture

Question 12

what is the smallest thing visible under a bright field microscope?

Answer 12

.2 micro meter or 200 nano meters

Question 13

what color light should you use to see the smallest objects?

Answer 13

violet light

Question 14

can you use the bright field microscope to see mycoplasma?

Answer 14

only under the best conditions

Question 15

can you use the bright field microscope to see viruses?

Answer 15

no

Question 16

can you use the bright field microscope to see bacteria?

Answer 16

yes

Question 17

what modification does the dark field microscope have?

Answer 17

a dark field stop located just under the condensor which blocks the light except for the light around the edges

Question 18

using a dark field microscope removes the need for __________

Answer 18

staining

Question 19

can you use live specimens with the bright field microscope?

Answer 19

no

Question 20

can you use live specimens for the dark field microscope?

Answer 20

yes

Question 21

can you use live specimens for the phase contrast microscope?

Answer 21

yes

Question 22

Name a specific example of an organism which can be seen under a dark field microscope

Answer 22

syphilis treponema pallidum

Question 23

Can you seen mycoplasma under a dark field microscope?

Answer 23

yes

Question 24

Name the two modifications on the phase contrast microscope that differ it from the bright field microscope

Answer 24

annular diaphragm

phase shifting element

Question 25

what does the annular diaphragm do?

Answer 25

Generates a ring of light which initiates the bending of the light (incident rays). Located below the condenser (lets through a rind of light that helps the light to bend)

Question 26

what does the phase shifting element do?

Answer 26

controlls the speed of the light by manipulating the brightness

Question 27

using the phase contrast microscope can you see mycoplasma?

Answer 27

yes

Question 28

Name the 3 modifications that a fluorescence microscope from a bright field one

Answer 28

exciter filter, barrier filter, fluorescent dye

Question 29

what does the exciter filter do?

Answer 29

blocks out wavelengths greater than 400nm (lets through UV light only)

Question 30

what does the barrier filter do?

Answer 30

blocks out wavelengths less than 500nm (protects eyes from UV light and gives a black field)

Question 31

what does the fluorescent dye do?

Answer 31

absorbs high energy of the light and releases visible light. Stains things with high amounts of lipids

Question 32

can you see mycobacterium tuberculosis?

Answer 32

yes

Question 33

what is immunofluorescence?

Answer 33

the fluorescence antibody technique | Uses antibodys and flourescent dye for staining if there is not enough lipid for the dye to stick to the organism

Question 34

what can you use immunofluorescence to diagnose?

Answer 34

syphilis

Question 35

what modification does a differential interference contrast microscope compared to a bright field one?

Answer 35

uses a prism to split the light and then recombine it

Question 36

can you see in 3D using the differential interference contrast microscope?

Answer 36

yes