1. Microscopes & Cell theory

2. Microscope development:
Hans and Zacharis Janssen: 1590 –simple microscope; 2 lens in a tube
Anton van Leeuwenhoek: early 1660’s- used microscope to observe nature & recorded it.

3. Describe the properties of microscopes.
Microscope: magnifies images
Magnification: increase in size
Resolution: increase in detail
Two types:
Light microscopes
Electron microscopes

4. Light Microscopes
Magnifies objects using light
Simple microscopes: have only one lens (magnifying glass)
Compound light microscope: has two lenses

5. Using the microscope:
Find total magnification: multiply power of eyepiece (usually 10X) x power of objective lens
When focusing: always start with LOW POWER objective
Move nosepiece all the way down and focus slowly UPWARD using the coarse adjustment

6. Electron Microscopes 1940’s, uses electron beams instead of light
Allows more detail, but specimens are usually killed in the staining process
Two types:
TEM: beam goes through specimen
SEM: scans surface only

7. Parts of a microscope Ocular lens: lens near eye
Eyepiece: holds ocular lens
Objective lens: lens near specimen
a. high power lens: longer, usually 40 X
b. low power lens: shorter, usually 10 X
Nosepiece: holds objective lenses
Stage: platform supporting specimen
Diaphragm: regulates amount of light
Fine adjustment/coarse adjustment: used to focus on object
Arm: supports microscope
Illuminator: light source

8. How did the Cell Theory come about?
Robert Hooke discovered cells in 1665
Examined a wine cork(tree)
looked like his monastery cell so he named them “cells”

9. Schleiden and Schwann (1838-1839) examined many types of cells
Schleiden: botanist, discovered that all plant parts are made of cells
Schwann: zoologist, discovered that all animals parts are made up of cells
Both observed / different types of cells performed different functions
Schwann 
Schleiden

10. Rudolph Virchow (1855)
Physician that stated all living cells come only from other living cells

11. The Cell Theory All organisms are made up of cells
Cell is the basic unit of organization
Cells come from pre-existing cells

12. Stem Cell Research Website-stem cell animation