1. Review of the Microscope

2. Who Invented the Microscope?
Some scientists have credited Zacharias Janssen of the Netherlands for inventing the optical microscope in the early 1600’s.
Anton van Leeuwenhoek, a Dutch biologist, has gotten more of the glory since his 18th century single-lens microscopes worked better and were more widely used. He was also the first to discover bacteria and protozoans.
From (History of the Microscope)

3. (Ocular)
Diaphragm

4. Microscope Parts & Functions
The lens you look through, magnifies the specimen.
Ocular Lens
Supports the microscope.
Base
Holds objective lenses.
Revolving nosepiece
Magnify the specimen.
Objective lenses
Supports upper parts of the microscope, used to carry the microscope.
Arm
Used to focus when using the high power objective.
Fine focus
Where the slide is placed.
Stage
Controls the amount of light reaching the objective lens.
Diaphragm
Used to focus when using the low power objective.
Coarse focus
Provides light.
Illuminator
Hold slide in place on the stage.
Stage Clips

5. Biological Drawing Rules
Drawing is neat and LARGE. Must take up most of the paper
Diagram is drawn in pencil and “coloured” using stipples (little dots)
All diagram labels are printed to the right of the drawing and are lined up in a straight line
Name and date are written in the upper right hand corner of the diagram
An appropriate title is given to the diagram
Lines between label and feature are drawn using a ruler
Lines do not cross
Calculations and qualitative observations are included at the bottom of the diagram
Mr. Kass
September 9, 2011
Amoeba
Endoplasmic reticulum
Mitochondria
Nucleus
Vacuole
M = ocular x objective
M = (10X) x (40X)
M = 400X
Specimen was transparent.
Nucleus appeared to be a pink/purple colour

6. 1) Magnification (M)
Definition: how many times bigger an image appears to the eye
Formula: M = ocular lens x objective lens
Ocular Power (eye piece)

7. Example
A student uses high power (40X) to look at a cell. The ocular lens has a power of 10X. What is the total magnification she is using?
M = ocular lens x objective lens
M = (10X) x (40X)
M = 400X 6 8

8. 2) Field of View (FV)
Definition: the diameter of the circle you see when you look down a microscope. (how much you can see)

9. Field of View (FV) Low FV = measured with a ruler (in mm) on low power
Use formulas for medium and high power:
Medium FV = FVLOW X (MLOW/MMEDIUM)
High FV = FVLOW X (MLOW/MHIGH)
Where “M” stands for magnification
Why can’t we use a ruler to measure FV for medium and high power?

10. 3) Specimen Size (SS)
Definition: the actual size of the object you are looking at (measure the greatest length you can find)
Formula: SS = FV / # of specimens that will fit across your FV
Example: The field of view in the diagram below is 27μm. What is the approximate size of the amoeba?
SS = 27 μm / 3
SS = 9 μm

11. 4) Diagram Magnification (DM)
Definition: how many times bigger your diagram (drawing) is compared to the actual specimen
Formula: DM = size of drawing (mm) / SS (in mm)

12. Skill 1: The Microscope In-Class Assignment
Work in pairs, hand in an individual assignment
For the paramecium OR animal cell slide, locate the specimen on your microscope and sketch a biological diagram
Use the biological diagram rules we discussed earlier as a checklist/rubric
Use the formulas you learned to calculate the actual size of the specimen
Will be marked out of 10 for communication
Key areas to remember:
Quality of the diagram counts
Correctness of calculations
Label any 3 cell parts (use the checklist/exemplar)
Sophistication of observations