1. Introduction to the Cell

2. Cell Theory All living things are composed of 1 or more cells.
In organisms, cells are the basic unit of structure & function
Cells are produced only from existing cells.

3. MICROSCOPES Light Microscope Electron Microscope (1950’s)
Transmission Electron Microscope
Scanning Electron Microscope

4. Light Microscope
works by passing visible light through a thin section of specimen and then through glass lenses
resolving power = 0.2 µm (size of small bacteria)
magnification about 1000x

6. Advantages of using Light Microscope:
Color image instead of monochrome
Larger field of view
Easily prepared sample material
Possible to observe living material & observe movement

7. Electron Microscope (1950’s)
uses electron beams which have shorter wavelengths of light
resolving power = 0.2 nm (most cell structures)
magnification up to 40,000x
Advantages

8. Electron Microscope Transmission Electron Microscope
electrons transmitted through specimen are focused and image is magnified using electromagnets
used to study internal cell structure
Scanning Electron Microscope
electron beam scans the surface of a spec.
useful for studying the surface of specimen in 3-D.

9. IMAGES
PINHEAD
Moth wing scales; Madagascan moon moth, Argema mittrei

10. Disadvantages to EM… can only view dead cells (elaborate preparation)
very expensive
zooxanthellae cells cultured from coral Aiptasia pulchella in a Scanning Electron Microscope

11. WE CAN ALSO STUDY CELLS BY...
Cell Fractionation = disrupting cells to separate out cell organelles
Centrifugation = spinning mixtures of cells and their parts at very high speeds; separates the components