Chapter 1 continued …… Microscopes (It would be difficult to study our cells and bacteria cells if we could not see them!!!)

The specimen scientists want to look at determines the types of microscopes they will use. Types of Microscopes: 1. Compound Light Microscope - Uses light to view specimen - Uses 2 lenses: ocular and objective lenses to focus and magnify specimen - Used for viewing live or dead thin specimens, can see a single cell. - Magnifies up to ~1000x

Chloroplasts in plant cells Chloroplasts in plant cells Figure 4.5Bx2

2. Stereoscope or Dissecting Microscope - Gives a 3-D image - Uses light to view specimen - Can be used to view larger live or dead specimens - Not capable of high magnification

Stereoscope/Dissecting Microscope

Sea lice on the skin of Atlantic salmon (Salmo salar L.) Sea lice on the skin of Atlantic salmon (Salmo salar L.) 5x

3. Electron Microscopes - Uses a beam of electrons to view specimen - Capable of high magnifications - Uses electromagnets to magnify and focus image - Can only view dead specimens!!!!

Photos of bacteria from SEM and TEM TEMSEM

-There are 2 types: - SEM: Scanning Electron Microscope - Scans the surface of the specimen - Gives a 3-D image of a whole specimen

Scanning electron microscope (SEM) Scanning electron microscope (SEM) Figure 4.1B Scanning electron micrograph of cilia Scanning electron micrograph of cilia Copyright 2003 Pearson Education, Inc as Benjamin Cummings

Transmission electron microscope (TEM) Transmission electron microscope (TEM) Figure 4.1C Transmission electron micrograph of cilia Transmission electron micrograph of cilia Copyright 2003 Pearson Education, Inc as Benjamin Cummings

- TEM: Transmission Electron Microscope - Sends a beam of electrons through a thin specimen. - Gives a 2-D image of internal cell parts.

Prokaryotic cells, Bacillus polymyxa Prokaryotic cells, Bacillus polymyxa Figure 4.4x1 Copyright 2003 Pearson Education, Inc as Benjamin Cummings