Tooth with plaqueMagnification: 10X

Toothbrush and ToothMagnification: 75X

Human Finger tipMagnification: 12X

Human Finger tipMagnification: 600X

Human Skin with BacteriaMagnification: 8,000X

MosquitoMagnification: 50X

Human CellsMagnification:10,000X

Embryonic HandMagnification 7X5 weeks

Embryonic HandMagnification 10X11 weeks

Human Embryo Magnification 10X16 weeks

Stomach Pit with Red Blood Cell and AcidMagnification: 3,000X

Human BrainMagnification: 5X

6 week Human EmbryoMagnification: 10X

The Microscope

• Microscope—tool used to study things too small to be seen by the unaided eye.

• History:– Invented by the Jansen

brothers in 1590.– Improved by Anton Van

Leeuwenhoek in the 1600’s.

• His first scope had a power of 270X.

• He made over 400 different microscopes.

• Known as the “Father of Microbiology.”

Anton Van Leeuwenhoek

Types of Microscopes• Compound Light Microscope —

uses lenses to magnify and light to illuminate. The most powerful can magnify 2000X. – Eyepiece —lens closest to the eye.– Objective lens —lens closest to the

object.– Total magnification —the power of

the eyepiece times the power of the objective.

– Example: 10X x 43X = 430X

Types of Microscopes

• Stereoscope —used to view larger objects. The light source is above the object, not below.

Types of Microscopes• Electron Microscope —uses magnets to focus a

beam of electrons.– Electrons are negatively charged particles.– Total magnification can be up to 1,000,000X.– Disadvantages—sometimes can not study living

organisms; expensive; too powerful– Types:

• Transmission Electron Microscope (TEM)—used to study internal parts of a specimen.

• Scanning Electron Microscope (SEM)—used to see the surface of whole objects.

• Scanning Tunneling Microscope—the most powerful. Invented in 1981. Has a magnification of 100 million times and a resolution of 1/100th the diameter of an atom.

Transmission Electron Microscope

• The TEM passes electrons through the object being studied. It can magnify as much as 200,000x but can not be used to observe living tissue.

• The TEM gives very detailed pictures of the internal structure of materials, either biological or non-biological.

Example: Golgi body of an a animal cell.

Scanning Electron Microscope• The SEM has a

magnification range of 15x to 200,000x and a resolution of 5 nanometers.

• It produces a detailed, three dimensional black and white image

35x 200x 1000x 35000x

• Specimens to be viewed by the SEM must be carefully dried to prevent shriveling and must be made to conduct electricity by coating them with a thin layer of gold in a machine called a sputter coater.

Sputter coater

Dried specimen

• Finally, the specimen is placed in the microscope’s vacuum column through an air-tight door. Air is pumped out and an electron gun emits a beam of high-energy electrons which is focused by a series of magnets.

• The Scanning Tunneling Microscope invented by John Wendelken and Joe Carpinelli. The microscope is nicknamed JEOL.

Eyepiece

Eyepiece Tube

BodyRevolving Nosepiece Objective lenses

Stage Stage Clips

Coarse Adjustment

Fine Adjustment

Diaphragm

Light

Base

Arm

Microscope Diagram

Microscope FlipchartActivity