microscopy

Question 1

Who created the microscope that allowed you to see bacteria?

Answer 1

Leeuwenhoek

Question 2

what magnification was the microscope Leeuwenhoek made?

Answer 2

300x

Question 3

What are the two main functions of the microscope?

Answer 3

magnification and resolution

Question 4

What is the ocular lens responsible for?

Answer 4

inverts what you are seeing

Question 5

What is the parfocal responsible for?

Answer 5

ensures you don’t have to adjust your focus when switching between objectives

Question 6

how many lenses are there on a microscope? what are they?

Answer 6

2, objective lense, ocular lense

Question 7

what are the 4 objectives lenses?

Answer 7

4x, 10x, 40x, 100x

Question 8

what magnification does the ocular lens have?

Answer 8

10x

Question 9

how do you determine total magnification?

Answer 9

objective lens x ocular lens

Question 10

what is resolution?

Answer 10

defined as the ability to distinguish two adjacent objects as distinct and separate

Question 11

Resolution was mathematically done by whom? when?

Answer 11

ernst abbe, 1870’s

Question 12

what are the two things resolution depends on?

Answer 12

physical property of light (wavelength) and numerical aperture

Question 13

what does numerical aperture (NA) refer to?

Answer 13

light gathering capabilities of a lens

Question 14

what is the equation for resolution?

Answer 14

R= 0.61λ / NA

Question 15

how do you enhance resolution?

Answer 15

you have a better image when R is small

Question 16

how do you make R small?

Answer 16

decreased the wavelength of light used and increase numerical aperture

Question 17

what is the equation of numerical aperture?

Answer 17

NA= n x sin(theta)

Question 18

why can you see better on 40x and 100x objectives?

Answer 18

they allow for more light so you can see your image more clearly

Question 19

As you move through objectives you are increasing ________ and thus enhancing the ________ through the ocular.

Answer 19

numerical aperture, resolution

Question 20

what is the 100x referred to as?

Answer 20

oil emergent objective

Question 21

why does oil help enhance the image?

Answer 21

because oil has a higher refractor index of 1.5 than opposed to air 1.0

Question 22

why doe you start with the 4x objective when looking at a sample?

Answer 22

it has the widest field of view

Question 23

how is dark field microscopy different?

Answer 23

uses the opaque light stop, and uses a dark background

Question 24

T/F you cannot use staining procedures when using dark field microscopy.

Answer 24

true

Question 25

when do you use dark field microscopy? example?

Answer 25

when samples are hard to stain, spirochetes

Question 26

what would you use phase contrast microscopy for?

Answer 26

use to look at unstained organisms that are ALIVE. Gives you the ability to watch motility and inclusion bodies of cells

Question 27

why cant you use stains on bacteria you want alive?

Answer 27

stains kill bacteria

Question 28

immunofluorescence microscopy typically requires a ______ attached to an _____.

Answer 28

flourophore, antibody

Question 29

confocal microscopy

Answer 29

when you concentrate the excitation light to a specific focal point. this can create 3D images of the cells

Question 30

z series

Answer 30

allows you to have that 3D image of the cells

Question 31

what is the advantage of using electron microscopy?

Answer 31

electrons have a much smaller wavelength of light which equals much higher resolution

Question 32

what level of magnification can electron microscopes have?

Answer 32

100,000x - 300,000x

Question 33

T/F electrons can go through glass

Answer 33

false, they cannot so we use electromagnetic lenses

Question 34

what do electromagnetic lenses do? what do they require when using them?

Answer 34

Control the beam of electrons, require a vacuum which protects them form vibrations

Question 35

what are the two types of electron microscopes?

Answer 35

transmission, scanning

Question 36

what kind of sample does the transmission electron microscope require?

Answer 36

extremely thin specimen (20-100nm)

Question 37

are you able to see some internal structures using the transmission electron microscope?

Answer 37

yes, but in 2D

Question 38

scanning electron microscope

Answer 38

electrons don’t pass through the sample, they just hit the sample.
the microscope collects what comes back at us (back scattered electrons and secondary electrons)

Question 39

back scattered electrons

Answer 39

electrons that originate from the beam

Question 40

secondary electrons

Answer 40

electrons from atoms within your sample