Using the Microscope
Laboratory 1
Biology 170
What did the invention of the
microscope enable?
• To study what organisms are made of
• 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
– A typical cell may be approximately 0.02 mm in
diameter and our eye is only able to see things as
small as 0.2 mm in diameter.
Today in Lab
Exercise 1: The Compound Microscope
Activity A: The parts of the Compound Microscope
Activity B: Using the Compound Microscope
Activity C: Depth of Focus
Exercise 2: Observing Cells
Activity A: Animal Cells
Activity B: Plant Cells
Exercise 3: The Stereoscopic Dissecting Microscope
Activity A: The Parts of the Dissecting Microscope
Activity B: Using the Dissecting Microscope
Exercise 4: Observing an Animal Specimen
Culture Microorganisms for Next Week…
Today in Lab
Exercise 1: The Compound Microscope
Activity A: The parts of the Compound Microscope
Activity B: Using the Compound Microscope
Activity C: Depth of Focus
Exercise 2: Observing Cells
Activity A: Animal Cells
Activity B: Plant Cells
Exercise 3: The Stereoscopic Dissecting Microscope
Activity A: The Parts of the Dissecting Microscope
Activity B: Using the Dissecting Microscope
Exercise 4: Observing an Animal Specimen
Culture Microorganisms for Next Week…
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
Magnification vs. Resolving Power
• Magnification
Def: ratio of image size to actual size; an apparent
enlargement of an object.
• Resolving Power
Def: a microscopes ability to distinguish between two
objects that are very close together as separate; what
allows us to see detail.
Why don’t our microscopes have more and/or higher
powered objectives?
Activity A: Parts of the Compound
Microscope
Activity B: Using the Microscope
ATTENTION! Important to follow these steps:
1. Plug in and turn on the light source. Adjust light source as needed.
2. Move the stage to its lowest position.
3. Make sure the lowest objective is in place (4x).
4. Place the slide on the stage and secure it with the slide clips/holder.
5. 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.
6. Looking through the eyepieces, use the course adjustment knob to bring
the slide toward the objective. Soon you will see the image come into
view.
7. After you get the image as clear as possible with the course adjustment,
use the fine adjustment knob to further focus the image.
8. 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
Activity C: Depth of Focus
Def: the thickness of the specimen that can be
seen in focus at any time
Preparing a Wet Mount
Today in Lab
Exercise 1: The Compound Microscope
Activity A: The parts of the Compound Microscope
Activity B: Using the Compound Microscope
Activity C: Depth of Focus
Exercise 2: Observing Cells
Activity A: Animal Cells
Activity B: Plant Cells
Exercise 3: The Stereoscopic Dissecting Microscope
Activity A: The Parts of the Dissecting Microscope
Activity B: Using the Dissecting Microscope
Exercise 4: Observing an Animal Specimen
Culture Microorganisms for Next Week…
Activity A: 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.
Oil Immersion
• PLEASE be very careful!!
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!!
Cheek Cells
• Stained with
methylene blue
• Only attaches to
DNA, so only see
nucleus
http://waynesword.palomar.edu/lmexer1.htm#cheek
Activity B: Plant Cells
In addition to the
nucleus, we will
also be able to see
the cell wall and
chloroplasts.
Elodea Leaf
http://waynesword.palomar.edu/lmexer1.htm#elodea
Elodea cytoplasmic streaming
http://www.youtube.com/watch?v=8edk6nGMwMs
Today in Lab
Exercise 1: The Compound Microscope
Activity A: The parts of the Compound Microscope
Activity B: Using the Compound Microscope
Activity C: Depth of Focus
Exercise 2: Observing Cells
Activity A: Animal Cells
Activity B: Plant Cells
Exercise 3: The Stereoscopic Dissecting Microscope
Activity A: The Parts of the Dissecting Microscope
Activity B: Using the Dissecting Microscope
Exercise 4: Observing an Animal Specimen
Culture Microorganisms for Next Week…
Exercise 3: Stereoscopic Dissecting
Microscope
Use when your
specimen is too large
or thick to see using a
compound microscope.
Activity A: Identify the
parts of the dissecting
microscope
Activity B: Using the
dissecting microscope
Exercise 4: Observing an Animal
Specimen
• Observe a hydra on a
depression slide (that you
will prepare)
• You will be feeding the
hydra liver juice and
Daphnia.
Hydra eating Daphnia
Today in Lab
Exercise 1: The Compound Microscope
Activity A: The parts of the Compound Microscope
Activity B: Using the Compound Microscope
Activity C: Depth of Focus
Exercise 2: Observing Cells
Activity A: Animal Cells
Activity B: Plant Cells
Exercise 3: The Stereoscopic Dissecting Microscope
Activity A: The Parts of the Dissecting Microscope
Activity B: Using the Dissecting Microscope
Exercise 4: Observing an Animal Specimen
Culture Microorganisms for Next Week…
Culturing Microorganisms for next week…
Purpose: We will be sampling microorganisms
in from our environment and observing the
effectiveness of antimicrobial agents.
– Be creative! – go inside the building, outside, UC,
etc.
– 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)
Using Antimicrobial Agents
• Divide your plate in half – put an
antimicrobial agent on half of the
plate
– Examples: listerine, vinegar, pine sol,
mikro-quat 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
Name
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
• Return materials in the same condition you
found them
• Ask questions if you do not understand
• Take thorough notes, draw pictures, and
answer all questions in your lab notebook
• Before you leave make sure your work station
is in the same condition as you found it.