1. Microscopes

2. There are two types of microscopes: 1) Light compound microscope – uses light to view specimens 2) Electron microscope – uses electrons to view specimens

3. Light compound microscope The light compound microscope has two lenses: - Objective lens: collects light passing through the specimen and forms a magnified image - Ocular lens: collects the magnified image from the objective lens and further magnifies this image

4. Electron microscope There are two types of electron microscopes: - Transmission microscope: electrons pass through the specimen - Scanning microscope: electrons rebound off the specimen Used to view smaller structures in cells that cannot be seen with a light microscope

5. The impact of technology Ongoing improvement of the light compound microscope meant higher quality images of cells The invention of electron microscopes (1933) led to the discovery of smaller structures within cells which provided greater knowledge and understanding Improvement in the preparation technique of specimens for viewing eg the use of dyes