1. Microscopes

2. Compound Light Microscope – Use lenses to magnify the image of an object by focusing light – Cell structures as small as 1 millionth of a meter – Magnification up to 2,000x – Classroom microscopes go up to 400x How Big? Animation

3. Magnification

4. Exploring the Cell Why are chemical stains/dyes used in microscopy? – Most living cells are nearly transparent – Stains allow the cells to be seen under the microscope – Some reveal only certain compounds and structures within the cell – Fluorescent dyes Different colors attached to different molecules Allows scientists to observe how materials move throughout the cell

5. Dissecting Microscope Also referred to as the stereo microscope designed for low magnification observation of a sample, typically using light reflected from the surface of an object rather than transmitted through it. 3D images used to study the surfaces of solid specimens or to carry out close work such as dissection, microsurgery, watch-making, and circuit board manufacture or inspection

6. Electron Microscopes – 2 types: Transmission (TEM) and Scanning (SEM) – Sends an electron beam through a vacuum to illuminate a specimen and produce a magnified image – Smaller cell structures as small as 1 billionth of a meter DNA Protein molecules Viruses

7. SEM vs. TEM SEM (Scanning Electron Microscope) 3D images up to 200,000x magnified focuses the electron beam to a very small point on the sample and scans over the sample to produce an image TEM (Transmission Electron Microscope) sends an electron beam through a thin sample, projecting an image on a fluorescent screen Cannot view the surface of specimens Up to 50 million times magnified Cool Electron Microscope Images