Chapter 4 Notes

1. Chapter 4 Notes Part II: Microscopy (refer to pg.60-61) Cells were discovered in the 17th century, when microscopes were invented….

2. Key term distinction • Magnification: the amount of times a specimen being viewed is enlarged in order to be seen, varies with power of microscope • Resolution: the ability that the microscope has to distinguish between two different objects, ie. The nucleus vs. the endoplasmic reticulum • Contrast: ability to see detail within the specimen clearly

3. Compound light microscopes • What we work with in class • Light rays pass through specimen and come into focus through two glass lenses. • The eyepiece lens gives a total of 10x magnification. The objective lens varies with microscopes but can be up to 100x magnification. Total magnification is found by multiplying eyepiece lens by objective lens.

4. Assorted types of light microscopes: • Bright-field – the most common used in compound-light microscopes • Phase contrast – microscope enhances density differences in specimen • Differential interference – computer enhancement • Darkfield – light passes through specimen at an angle, helpful in viewing organelles • SEE PAGE 61!

5. Transmission Electron Microscopes • Use electrons to pass through specimens to view detail; image projected onto screen or photographic film

6. Scanning electron microscopes • The specimen is first coated with a thin layer of metal and an image is produced by the electrons which bounce off of the image

7. Immunofluorescence microscopy • Uses fluorescent antibodies to reveal proteins in cells • Can look at specific proteins in detail

8. Confocal microscopy • A major advancement in microscopic illumination • Uses a laser beam to focus on a shallow plane within cell which creates 3-D images

9. Today’s lab • Microscope intro • WS due next time! • READ directions and FOLLOW PROCEDURES!!!