3 Microscopy
1. What is a millimeter?
1 thousandth of a meter (1m / 1,000)
10-3meter
denoted by mm
2. What is a micrometer?
1 millionth of a meter (1m / 1,000,000)
10-6meter
denoted by µm
3. What is a nanometer?
1 billionth of a meter (1m / 1,000,000,000)
10-9meter
denoted by nm
4. What is 1 meter equivalent to in millimeters?
1m = 1,000mm
5. What is 1 meter equivalent to in micrometers?
1m = 1,000,000 µm
6. What is 1 meter equivalent to in nanometers?
1m = 1,000,000,000 nm
7. What is 1mm equivalent to in µm ?
1mm = 1,000µm
8. What is 1mm equivalent to in nm ?
1mm = 1,000,000nm
9. What is 1µm equivalent to in nm?
1µm = 1,000nm
10. What size are Bacteria?
Bacteria are about 1µm or smaller
1 millionth of a meter
10-6meter
11. What size are viruses?
Viruses are about 1nm
1 billionth of a meter
10-9meter
12. How many Viruses could fit into one
1,000 Viruses could fit into 1 Bacterium
Bacterium?
13. What are the two commonly used types of
Simple and Compound
microscopes?
14. How many lenses does each microscope have? Simple has one (ocular)
Compound has one or more (ocular plus objective)
15. Give an example of a compound microscope.
Brightfield
16. What are the different types of compound
microscopes?
17. What type of microscope is used to look at
large objects?
18. When is a brightfield microscope used?
19. When is darkfield illumination needed?
Light microscope and Electron microscope
Dissecting microscope
a. It is used for looking at live organisms with no
stain.
b. It can also be used for stained tissues.
a. It is used for live organisms with no stain.
b. It is also used to look at fluorescent organisms.
1
3 Microscopy
20. What is the difference between brightfield
and darkfield illumination?
Brightfield Illumination:
Darkfield Illumination:
21. What is Phase Contrast Microscopy used for?
22. What is Differential Interference Contrast
used for?
23. 19. Describe Fluorescence Microscopy
24. What is difference between regular
microscopes and Transmission Electron
Microscopes?
25. Are cells live or dead with a Transmission
Electron Microscope?
26. What is the difference between a Scanning
Electron Microscope and a transmission
electron microscope?
27. What happens in a Scanning Probe
Microscope and how does it affect the color?
Used for seeing organelles in live organisms, 2D
Used for seeing organelles in live organisms in three
dimensions
Cells are stained with fluorescent dyes (called
fluorochromes). UV Light is shined on the
specimen. Fluorescent substances absorb UV light
and emit visible light
Transmission Electron Microscopes have a much
higher resolution than regular microscopes.
You can only view dead cells under the transmission
electron microscope.
Scanning Electron Microscope has a very high
resolution like a transmission electron microscope
except it makes images in three dimensions.
Scanning Probe Microscope passes a scan over the
specimen, line by line. The surface dimensions are
recorded and sent to a computer, which shows the
image in false color.
28. Brightfield microscopy:
BrightfieldAre cells live or dead?
Cells are either live and unstained or dead and
Are cells stained?
stained.
How does the object and background appear? Dark objects are visible against a bright background.
2
3 Microscopy
29. Darkfield microscopy:
Are cells live or dead?
Are cells stained?
How does the object and background appear?
What cell structures can be seen?
30. Phase-Contrast
Are cells live or dead?
Are cells stained?
Are images three dimensional?
What cell structures can be seen?
31. DIFFERENTIAL INTERFERENCE CONTRAST
Are cells live or dead?
Are cells stained?
Are images three dimensional?
What cell structures can be seen?
How is resolution?
32. FLUORESCENCE
Are cells live or dead?
Are cells stained?
When is this used?
33. TRANSMISSION ELECTRON
Are cells live or dead?
Are cells stained?
Are images three dimensional?
What cell structures can be seen?
How is resolution?
34. SCANNING ELECTRON
Are cells live or dead?
Are images three dimensional?
What structures can be seen?
35. SCANNING PROBE
Describe how it works
What are 2 drawbacks?
DarkfieldCells are live
No stain is used
Light objects are visible against dark backgroundCan see signs of motility from cilia and flagella
Phase-ContrastCells are live
No stain is used
Not three-dimensional
Can see signs of motility from cilia and flagella more
clearly than darkfield
DIFFERENTIAL INTERFERENCE CONTRASTCells are live
No stain is used
Shows three dimensions
Can see signs of motility from cilia and flagella more
clearly than darkfield or phase contrast
Best resolution for live cells
FLUORESCENCECells are dead
Stain is fluorescent dye- creates visible light
Quick diagnosis of TB & Syphilis
TRANSMISSION ELECTRONCells are dead
Stain with heavy metal salts is used
Images are not 3D
Can see organelles in cells
Best resolution of all microscopes
SCANNING ELECTRONCells are dead
Images are 3D
Surface view only
SCANNING PROBESpecimen is scanned, image is sent to computerDrawback: Slower in acquiring images
Drawback: Max image size is smaller
3