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Microscopes & Cell theory. 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. Describe the properties of microscopes. Microscope: magnifies images

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microscope development
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.
describe the properties of microscopes
Describe the properties of microscopes.
  • Microscope: magnifies images
  • Magnification: increase in size
  • Resolution: increase in detail
  • Two types:
  • Light microscopes
  • Electron microscopes
light microscopes
Light Microscopes
  • Magnifies objects using light
  • Simple microscopes: have only one lens (magnifying glass)
  • Compound light microscope: has two lenses
using the microscope
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
electron microscopes
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
parts of a microscope
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

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”

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




Rudolph Virchow (1855)

  • Physician that stated all living cells come only from other living cells
the cell theory
The Cell Theory
  • All organisms are made up of cells
  • Cell is the basic unit of organization
  • Cells come from pre-existing cells
stem cell research
Stem Cell Research

Website-stem cell animation