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 Magnification: increase in size Resolution: increase in detail Two types: Light microscopes Electron microscopes

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

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 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 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 Schwann  Schleiden

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

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 Website-stem cell animation http://www.sumanasinc.com/webcontent/anisamples/stemcells.html