1. Tools of the Biologist The Incredible World of Microscopes video

2. History Anton Von Leeuwenhoek Born in Holland 1632
First to observe living bacteria & drew them.
Also looked at protists, sperm, blood
Used a simple scope
Made over 500 "microscopes"

4. Robert Hooke (1665)
Used compound scope to examine cork.
Coined the term “cell” referring to the many little boxes. Actually saw dead plant cells.

5. Types of Microscopes
1. Simple microscope – Hand lens (magnifying glass)
3 – 40 times magnification

6. Compound Light Microscope Most commonly used microscope
The type we use in our labs
Most commonly used microscope
Uses light and lenses to magnify & view the specimen
Has two sets of lenses – Ocular (eye piece) & Objective (near the object being viewed)
Total magnification on our scopes = 40 – 1000 times
Total magnification = Ocular (10X) x Objective (40X)

7. Ocular – Eye piece
Neck – Supports the eyepiece.
Objectives – 4 – 100x magnification
Arm – Supports neck and objectives. Carry by this
Stage and clips – Holds slides in place
Adjustments – Coarse & Fine. Focuses image
Diaphragm – Controls the amount of light coming through the stage
Light – Electric light source
Base – Bottom of scope. One hand goes underneath

9. The Diaphragm Use the Diaphragm to adjust the amount of light
Image of pollen grain under good brightness (left) and poor brightness (right)
Image of pollen grain with good contrast (left) and poor contrast (right)

10. Focusing Use the Adjustment knobs to focus the image
Coarse adjustment brings the image into near focus
Fine adjustment (smaller knob) brings it into fine focus

11. Resolution
Ability to clearly distinguish two objects that are close together.
Image of pollen grain with good resolution (left) and poor resolution (right)
Resolving power of our scope = 0.2um

12. Rules for using the Microscope
Use only the assigned microscope
Carry & place the scope properly (6cm from edge of table)
Do not let the cords dangle or get into the sinks
Clean lens only with lens paper. NO FINGERS!
Do not reuse the same spot on your lens paper
Start on low (4x) power when you start your observations
Always focus (move the stage) away from the slide
Use the coarse adjustment first then the fine adjustment
Be careful when switching to high (40x) power to se that there is enough clearance between the objective and the slide
Do not use the coarse adjustment knob on high (40x) power
When you are done with the scope, turn off the light switch
Always put scope away with cord wrapped around it, cover on & the low power objective in place
Put scopes away with the numbers facing out into the proper slot
Clean and dry all slides and cover slips before putting them away

13. Wet Mount Clean slide View specimen Add drop of water to specimen
Put coverslip at a right angle into the side of the water
View specimen

14. Making a Wet Mount Slide
1. Gather a thin slice/piece of whatever your specimen is. If your specimen is too thick, then the coverslip will wobble on top of the sample like a see-saw:
2. Place ONE drop of water directly over the specimen. If you put too much water over the specimen, then the coverslip will float on top of the water, making it harder to draw the specimens as they float past the field of view!
3. Place the coverslip at a 45 degree angle (approximately), with one edge touching the water drop, and let go.

15. The Letter “e”
40x x

16. Threads
100x

17. Beware of Air Bubbles!!

18. Compound Microscope images
Diatom
Paramecium
Amoeba
Vorticella
Daphnia
Hydra budding

19. 3. Binocular (Has two oculars)
Gives a 3D image.
Also called a Dissecting scope or Stereo scope
Monocular (1 ocular) Light Microscope
2D image

20. Since most of the specimens we observe will be clear to near clear, what could be done to enhance the image we view through the scope?
Adjust the diaphragm to allow less light to come through
Use a Stain to make transparent specimens visible. Ie. Iodine, methyl blue
Specimens must be sliced very thin. Use a Microtome to make thin slices

21. Calculating Fields of View
Once you have your field of view for Low Power, you will no longer use the ruler: GIVE BACK THE RULER
For Medium Power:
Low Power Field of View (um) = Medium Power Mag
Medium Power Field of View (um) Low Power Mag
For High Power:
Low Power Field of View (um = High Power Mag
High Power Field of View (um) Low Power Mag
Medium Power Field of View
Low Power Field of View

22. Field of View 4 cells fit across field Diameter = 3.75 mm
Specimen = 3750um 4
Diameter = 3.75 mm
or 3750 um
Length of Specimen =937.5um

23. Electron Microscopes
Uses electromagnets and streams of electrons to view a specimen
Limit of Resolution is 1000x finer than light microscope
200,000 – 1,000,000x magnification

24. Two types
Transmission Electron Microscope (TEM) (Germany) Side
Image is seen on a fluorescent screen
Specimen must be thinly sliced and coated with Au or Ag.
Gives a 2D image of specimen
Specimen must be dead

25. Herpes simplex viruses
Staphylococcus aureus
These have all had color added to them!!!
E. coli bacteria

26. Scanning Electron Microscope (SEM) – 1935 (Germany)
Gives a 3D image
Electrons scan around specimen
Shows only the outside of the specimen
Gives very clear surface details

28. Images
Diatom
Weevil
Tick
Radiolarian

29. Gold coater - $1,950 used
Transmission Electron Microscopes (TEM):$90,000 - $2,000,000
UsedScanning Electron Microscopes (SEM):$45,000 - $200,000 Used

31. Limitations of Electron Microscopes
Specimens must be very thin (TEM)
Specimens must be stained or coated
Specimens must be dried out (Mounting chamber is vacuum sealed)
Specimens must be dead
Black and white images only! Any color you may see is added in