VIEWING CELLS:
USING THE COMPOUND LIGHT
MICROSCOPE & STAINS
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I. Parts of the Microscope
1. Eyepiece:


Lens closest to the
eye
AKA “ocular”
2. Body Tube:

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Connects the
eyepiece to the
objectives
I. Microscope Parts (continued)
3.
Low Power
Objectives:
 Shortest lenses
4.
High Power Objective:
 Longest lens;
closest to the slide
 DO NOT USE WITH
COARSE FOCUS
KNOB
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I. Microscope Parts (continued)
5.
Stage:
 Where the slide
is placed
6.
Stage Clips:
 Clips that hold
the slide in
place
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I. Microscope Parts (continued)
7.
Diaphragm:

8.
Light Source:

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Adjusts the amount
of light entering
from the light
source onto the
specimen
Provides light to
illuminate the
specimen
I. Microscope Parts (continued)
9.
Arm:
 Where you
should always
hold & carry
the
microscope
Base:
 The bottom of
the
microscope
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I. Microscope Parts (continued)
11.
12.
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Coarse Adjustment
Knob:
 Roughly focuses
the specimen.
 USE ONLY WITH
THE LOW
POWER
OBJECTIVE
Fine Adjustment
Knob
 Sharply focuses
the specimen on
both low and
high power
.
.
Biology the Parts
II.Regents
Labeling
Ocular
Body tube
Nosepiece
Low Power Obj.
Arm
Med. Power Obj.
High Power Obj.
Stage Clips
Diaphragm
Stage
Course Adj. Knob
Fine Adj. Knob
Light
Base
Biology the Parts
II.Regents
Labeling
TOTAL MAGNIFICATION
 Powers of the eyepiece (10X) multiplied by
objective lenses determine total magnification.
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IV. Image Appearance
 When viewing a specimen through a
microscope, the image is distorted.

What does that mean?
 Images appear upside-down
AND backwards
 Example: The letter “e”:
Original
Image:
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Image Under
the
Microscope:
FIELD OF VIEW
 The area of the slide you view through
the microscope
 Magnification increase, FOV decreases
 As you zoom in you see LESS of the
specimen on the slide
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Wet Mount
 Wet Mount: liquid suspension observable
under a light microscope
1.Place your specimen on a glass slide.
2.Add 1-2 drops of liquid (water) to the
slide.
3.Gently lower a coverslip at an angle onto
your wet specimen. This reduces air
bubbles.
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Wet Mount Slide
Adding solution without removing coverslip:
1. Place pipette with stain near coverslip
2. Place piece of paper towel on opposite
side of coverslip
3. Add stain/solution from pipette
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What are stains? How can we test
substances for organic compounds?
 Chemical Stain:
 A chemical that is used to make a cell
visible (ex: iodine, BTB)
 Chemical Indicators:
 A substance which detects the presence
of a specific element or compound
 We can test for any organic compound
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Bromthymol Blue
 Can be a stain OR


indicator
Stains cells blue
Indicates presence
of Carbon Dioxide
by turning from
blue to yellow
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Lugol’s Iodine Test
 Can be a stain or
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indicator
 Tests for the
presence of Starch
 A positive test results
in the iodine
changing in color
from red/brown to
BLACK
 As a stain, makes
cells appear amber
Benedict’s test
 Tests for the

presence of
glucose
The solution
changes from
clear blue to
opaque
ORANGE in a
positive test
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Measuring Cell Size
We can use microscopes to estimate the size of
cells we are looking at
If we know the diameter of the field of our field of
view we can then estimate the size of the cells
1 meter (m) = 1000 millimeters (mm)
1 millimeter (mm) = 1000 micrometers (µm)
1 meter (m) = 1,000,000 micrometers (µm)
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MICROMETERS
 μm =



MICROMETER
WHAT DOES A
MICROMETER
EQUAL?
1,000 μm = 1 mm
Conversion:
___mm * 1000 =
____μm
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Measuring Field of View
1. Place metric ruler on the microscope
stage we can determine how many
millimeters the diameter of the FOV is
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Estimating the size of a cell: Using your
estimate of the diameter of the FOV, you can
estimate the size of a cell.
Use the formula:
Size of cell = diameter of field
# of cells
How many cells fit across the
diameter of the field? ________
If the diameter of the field is 1.5
mm, estimate the size of
each cell:
_______ mm
_______ µm
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a) if the field of view = 1 mm
Field of
view
Onion cell
1mm (1000 µm)
then onion cells are
0.5
__________ mm
500 microns
or ______________(µm)
in length
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b)if the field of view = 0.5 mm or 500µm
then these cheek cells would be
500
5
100
mm or ______________
µm in length
Human
cheek cell
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0.5 mm (500 µm)