1. Chapter 3: Cell StructureSection 1: Looking at Cells 1 Cell Structure Chapter 3

2. Chapter 3: Cell StructureSection 1: Looking at Cells 2 Objectives Relate magnification and resolution in the use of microscopes Analyze how light microscopes function. Compare light microscopes with electron microscopes. Describe the scanning tunneling microscope.

3. Chapter 3: Cell StructureSection 1: Looking at Cells 3 Microscopes Microscopes allow scientists to see what cannot be seen with the unaided eye.

4. Chapter 3: Cell StructureSection 1: Looking at Cells 4 Microscopes Properties of Images Magnification Resolution

5. Chapter 3: Cell StructureSection 1: Looking at Cells 5 Microscopes Magnification = the apparent increase in the size of the image

6. Chapter 3: Cell StructureSection 1: Looking at Cells 6 Microscopes Resolution = the increase in visible details

7. Chapter 3: Cell StructureSection 1: Looking at Cells 7 Microscopes

8. Chapter 3: Cell StructureSection 1: Looking at Cells 8 Microscopes Types of Microscopes Compound light microscopes Electron microscopes

9. Chapter 3: Cell StructureSection 1: Looking at Cells 9 Microscopes Compound light microscopes use 1.Light reflected off of or passing through an object to produce an enlarged image.

10. Chapter 3: Cell StructureSection 1: Looking at Cells 10 Microscopes 2.Two kinds of lenses Ocular lens—lens set nearest the viewer’s eye Objective lenses—lenses nearest the specimen

11. Chapter 3: Cell StructureSection 1: Looking at Cells 11 Microscopes Lens magnification is indicated by a number followed by X.

12. Chapter 3: Cell StructureSection 1: Looking at Cells 12 Microscopes Total Magnification Calculated by multiplying the magnifications of the ocular and objective lenses. Ocular magnification ……………10X x Objective magnification………….40X Total magnification……………...400X

13. Chapter 3: Cell StructureSection 1: Looking at Cells 13 Microscopes Light microscopes have limited use, practical magnification is limited to 1000X.

14. Chapter 3: Cell StructureSection 1: Looking at Cells 14 Microscopes Electron microscopes –Use a beam of electrons –Produce images of very high magnification and resolution * * up to 50 million X according to some sources

15. Chapter 3: Cell StructureSection 1: Looking at Cells 15 Microscopes Electron microscopes –Both electron beam and the specimen must be placed in a vacuum chamber, so living cells cannot be viewed.

16. Chapter 3: Cell StructureSection 1: Looking at Cells 16 Microscopes Types of electron microscopes Transmission (TEM) Scanning (SEM)

17. Chapter 3: Cell StructureSection 1: Looking at Cells 17 Microscopes Transmission Electron Microscope (TEM) Reveals the fine details of a cell’s internal structure.

18. Chapter 3: Cell StructureSection 1: Looking at Cells 18 TEM micrograph

19. Chapter 3: Cell StructureSection 1: Looking at Cells 19 Microscopes Scanning Electron Microscope (SEM) Produces three-dimensional images of cell surfaces

20. Chapter 3: Cell StructureSection 1: Looking at Cells 20 SEM micrograph

21. Chapter 3: Cell StructureSection 1: Looking at Cells 21 Guided Practice 1.What is the difference between magnification and resolution? –Magnification means to make an image larger, while resolution refers to the sharpness of the image.

22. Chapter 3: Cell StructureSection 1: Looking at Cells 22 Guided Practice 2.Compare the magnifying power of a light microscope with the magnifying power of an electron microscope. –Light microscopes can magnify objects up to 1000X. Electron microscopes can magnify an object up to 200 000X.

23. Chapter 3: Cell StructureSection 1: Looking at Cells 23 Guided Practice 3.What is the main advantage of the transmission electron microscope? –It shows a cell’s internal structure in fine detail.