Using the Microscope
Laboratory 1
Biology 171
Today in Lab
Microscope
Exercise 1: The Compound microscope
- Parts of the Compound microscope
Exercise 2: Technique
- Field of view, depth of field, magnification
Exercise 3: Using the microscope
- prepping a wet mount slide, looking at Elodea
Exercise 5: Cell organization and complex processes
- Trichonympha, symbiosis
- cell types (animal and plant)
Bacteriology
Culture microorganisms for Next Week…
What did the invention of the
microscope enable?
• DUH…. to look at tiny stuff
• Individual cells could be observed
– Allowed scientists to see that all cells
are very similar, but often take on
different functions
• Allowed us to see very small things
– Typical cell = 0.02 mm
– Our eyes can only see 0.2 mm
• Invented around 1675; telescopes
around 1605.
• Fundamentally changed how we
saw ourselves and nature.
Dutch Inventor: Antoni van
Leeuwennhoek
Determining Total Magnification
Multiply the magnification of each set of lenses:
Total magnification =
magnification of objective
X
magnification of eyepiece
Scanning power:
10
4
eyepiece ______x
times objective _____x
Low power:
eyepiece ______x times objective _____x
High power:
eyepiece ______x times objective _____x
Oil immersion power:
eyepiece ______x times objective _____x
40
= _____x
= _____x
= _____x
= _____x
Page 4, lab manual
Parts of the Compound Microscope
Note: know these parts for the quiz!
Using the Microscope
ATTENTION! Important to follow these steps:
1. Plug in and turn on the light source. Adjust light source as needed.
2. Clean the objective lens with lens paper and Windex
3. Move the stage to its lowest position.
4. Make sure the lowest objective is in place (4x).
5. Place the slide on the stage and secure it with the slide clips/holder.
6. Use the stage controls to center the slide over the light source. Look at the slide from
the side of the microscope, not through the eyepieces.
7. Looking through the eyepieces, use the coarse adjustment knob to bring the slide
toward the objective. Soon you will see the image come into view.
8. After you get the image as clear as possible with the coarse adjustment, use the fine
adjustment knob to further focus the image.
9. You may now go to a higher objective if you want, but be sure to ONLY use the fine
adjustment knob to focus. (Also, be sure you are going to the next highest objective
and NOT the oil immersion). The microscope objectives should be parfocal, as an
image is focused with one objective, it will also be in focus in the other objectives.
Field of View
We will be using a ruler to measure the field of view.
What is the field of view in this image?
7 mm
Micrometer
The images we will be looking at under the microscope are
often too small to be measured in millimeters.
Thus, we use the micrometer…
1 mm = 1000 µm
1 µm = 0.001 mm
7 mm = ? µm
Remember our conversions:
1 mm = 1000 µm
1 µm = 0.001 mm
1 µm = 1 x 10-3 mm
7 mm (1000 µm/1 mm) = 7000 µm
7 mm (1 x 10-3 µm/mm)= 7000 µm
*Note: about 1/3 of previous students miss this question on the quiz.
Depth of Focus
Def: the thickness of the specimen that can be
seen in focus at any time
Preparing a Wet Mount
Pro tip: Use a Kimwipe to absorb extra water. This will suck the cover slip
down to the slide and prevent “wobble.”
Quick note:
Oil Immersion
• PLEASE be very careful!!
• 100 x objective ONLY
Procedure:
1. After focusing in the high power objective, move
the nosepiece half way between this and the oil
immersion objective.
2. Place a small drop of oil on the coverslip.
3. Move the oil immersion objective into and
through the oil and secure in position.
4. ONLY use the fine adjustment (and only a little
bit) to focus
Oil Immersion cont.
• After you are finished, be sure to wipe the oil immersion lens
with LENS paper and LENS CLEANER to remove the oil. ONLY
use lens paper or else you will damage the objectives.
• Seriously. Use lens paper, not Kimwipes.
3 domains of life
Inside Eukarya
- Most (but not all!) organisms
are unicellular
- If it’s not a plant, animal, or
fungus, it’s called a protist
- Protists are “paraphyletic” and
make up the vast majority of
eukaryotic diversity.
Amoebas – page 15
Amoeba proteus
Pseudopodia –
temporary extensions of
amoeboid cells, function
in moving and engulfing
food
Phagocytosis – The act of
engulfing food
Where does this
organism get its energy
from?
Physarum (plasmodial stage)
Is slime mold smarter than Japan's
railway engineers? check it out at
home. It’s pretty neat. 1 point EC on
the quiz next week possible.
Slime Mold Life Cycle
Trichonympha – pg 16
• Lives in the intestine of the termite
• Bacterial endosymbionts inside Trichonympha
digest cellulose
- Termite > Trichonympha > Spirochetes
Procedure
1.
2.
3.
4.
5.
6.
Place a couple of drops of Ringer’s solution on a clean slide.
Transfer a termite into the drop of solution.
(Troika dolls)
Place slide under a dissecting microscope.
Place the tips of dissecting needles at either end of the termite and pull in
opposite directions.
Locate the long tube that is the termite’s intestine.
Place a cover slip over the specimen and lightly press down on coverslip to
release the Trichonympha from the intestines. Observe with a compound
microscope.
Can you see the spirochetes, too? If so, show me!
A word on symbiosis…
An interaction between
organisms that is mutually
beneficial.
Protococcus & Scenedesmus, pg 17
(Do this part last, if you’ve got time).
Plant Cells
In addition to the
nucleus, we will
also be able to see
the cell wall and
chloroplasts.
Elodea Leaf, pg 19
http://waynesword.palomar.edu/lmexer1.htm#elodea
Elodea cytoplasmic streaming
Moves nutrients, genetic info, raw
material throughout the cell using
actin proteins.
Why does this happen?
Animal Cells
Most structures in
animals cells are
too small to see.
We will be able to
see the plasma
membrane and the
nucleus today.
Cheek Cells, pg 20
• Stained with methylene
blue
• Only attaches to DNA, so
only see nucleus
• Fun fact: methylene blue
may be a treatment for
malaria, cancer, alzheimer’s
and cyanide poisoning.
http://waynesword.palomar.edu/lmexer1.htm#cheek
Culturing Microorganisms, pg. 45
Purpose: We will be sampling microorganisms in from our
environment and observing the effectiveness of antimicrobial
agents.
– Be creative! – The UC! Outside! Between your toes!
– Find a unique area to sample
– Or a few groups could sample the same surface and test
the effectiveness of different antimicrobial agents
Work in pairs 
(not enough agar plates)
(Note: we may not do this portion of the lab)
Using Antimicrobial Agents
• Divide your plate in half – put an
antimicrobial agent on half of the plate
– Examples: listerine, vinegar, pine sol, mikroquat disinfectant
• Only need a little bit so it doesn’t diffuse
over to other half of plate
• Write on the BOTTOM of the plate (not on
lid) and indicate what half has the
antimicrobial agent
What to include on BOTTOM of plate
Antimicrobial
agent
Names
Lab Section
Surface Sampled
Date
NO antimicrobial
agent
Culturing Microorganisms
Procedure:
1. Wet a cotton swab with sterile water and swab the environmental
surface
2. Inoculate an agar plate on both halves of the plate – do the side
WITHOUT the antimicrobial agent FIRST
3. After innoculation…
• Put the lid on the petri dish
• Flip the whole dish upside down
• Make sure your name and lab section (day) are on the bottom
• Make a pile on the front desk
REMINDERS:
• Work productively and efficiently
• Think creatively, critically, and freely. ASK QUESTIONS!
• Take thorough notes, draw pictures, answer all questions in your lab
notebook, and come up a QHM based on microorganisms or something
you saw today.
• Before you leave, make sure the lab is in the same condition as you found
it.
• Don’t forget! QHM – Question, Hypothesis, Methods
• Also: be sure you know how to access the website, and have spoken with
me personally if you are concerned about your writing ability and the
research paper.