Review of the Cell TheoryReview of the Cell Theory

3 statements make up the cell theory:

1.All living things are composed of one or more cells.

2.Cells are the basic structural and functional units of life.

3.All cells arise from the division of other cells.

The MicroscopeThe MicroscopeThere are many different types of

microscopes, we will learn about 4 types.

1.The Simple Light Microscope

2.The Compound Microscope

3.The Transmission Electron Microscope (TEM)

4.The Scanning Electron Microscope (SEM)

1. The Simple Light Microscope1. The Simple Light MicroscopeHand held, made of a

single lens

Used by 17th century biologist Anton van Leeuwenhoek

2. The Compound Light 2. The Compound Light MicroscopeMicroscope 2 lenses: ocular and objective

Illuminated with a bulb

Total Magnification = ocular x objective

Cannot resolve parts of a specimen closer together than 200 nm

3. Transmission Electron 3. Transmission Electron MicroscopeMicroscope

An invisible beam of electrons pass through a very thin specimen

Specimen is coated in plastic and shaved very thin...only dead specimens!

Designed and built in 1937 at U of T

Magnify 5 000 000 x and resolve up to 0.2nm

TEM cont’dTEM cont’d

4. Scanning Electron Microscope4. Scanning Electron MicroscopeThicker, whole specimens can be

usedThin stream of electrons scans

surface of specimen to produce a 3D image

Less mag and resolution than TEM, but greater contrast and depth

Mag up to 300 000x and resolution of 10nm

SEM cont’dSEM cont’d