2. Microscopes The Discovery of Cells

3. Quiz Number paper from 1-5 Identify the following pictures

4. Question 1

5. Question 1: Bacteria

6. Question 2

7. Question 2: DNA

8. Question 3

9. Question 3: Breast Cancer Cell

10. Question 4

11. Question 4: Alga- red tides

12. Question 5

13. Question 5: Bed bug

14. Learning Targets 1. Describe how a microscope works. 2. Calculate the total magnification of an image. 3. Compare the different types of microscopes. Why? To see microscopic world

15. How does a microscope work? Magnification enlargement of an object compare size of image to actual size of object total magnification ocular power x objective power = total magnification

16. Microscopes

17. Resolution – capacity to show 2 points that are close together as separate.. 10x1000x Poor Resolution = Blurry Image Good Resolution = Clear Image

18. Resolution

19. How does a microscope work? Parfocal both low and high power objectives are adjusted to the same focus easily switch between both objectives

20. What happens as magnification increases? 1. field of view decreases 2. brightness decreases 3. resolving power increases

21. Staining  Coloring cell structure With dyes to reflect light  Certain cell parts absorb certain stains  Kills cells or disturbs contents  Vital stains-dyes that highlight structures in living cells

22. What are the different types of microscopes? Compound light microscope Stereoscopic dissecting microscope Electron microscope

23. Compound Light Microscope

24. has 2 or more lenses (eyepiece and objective) uses transmitted light (light passes through object) must use thin specimen so light can pass thru can use live specimens usually doesn’t exceed total mag. of 2000x Our scopes in class are capable of 400x only see specimen in 2D

25. Compound Microscope Images Human Hair (x 400) Mite Paramecium

26. Compound Light Microscope Structures & Functions

27. Compound Light Microscope Eyepiece/Ocular – The lens through which the scientist looks Body Tube – Connects eyepiece to microscope Revolving Nosepiece – Holds 3-4 objectives (magnifying lens), turns for objective selection.

28. Compound Light Microscope Scanning Objective - Used for locating objects & scanning the slide quickly (Red Line- 4X) Lowest power objective Low Power Objective – Lens that allows you to find & center the object on a slide. Yellow line around the objective (10x) High Power Objective - Lens that zooms in for closer viewing (40X) Blue line around high power

29. Compound Light Microscope Stage – platform upon which the slide rests Mechanical Stage – movable clips that hold & move the slide Iris Diaphragm – transparent lens through which light travels. Size and brightness can be adjusted. Lamp – light source needed for viewing the specimen

30. Stereoscopic Dissecting Microscope uses reflected light to produce image range of magnification 10x-60x

31. Images from a Stereoscope Penny – Abe’s face Penny – back Beetle

32. Stereo Dissecting Microscope 2 eyepieces to produce 3-D image Uses reflected light to illuminate surface of specimen Used on large objects which light cannot pass through Magnifies object 5x – 60x

33. Electron Microscope 2 Types Scanning electron microscope (SEM) Transmission electron microscope (TEM)

34. Electron Microscope Discovered in Germany in 1930’s and 1940’s Uses beam of electrons to see image NOT light Image is produced on a T.V. monitor in black & white (no light) Much higher resolution Limitations Can’t view living things due to vacuum in interior Very expensive Very big, must have own foundation

35. Transmission electron microscope (TEM) Electrons go through very thin slice of specimen – detailed image on T.V. screen 200,000x (can be increased to 1,000,000x)

36. Images from a TEM Bacteria E.coli bacteria dividing Leaf

37. Scanning electron microscope (SEM) Beam of electrons across a whole specimen (sprayed with fine metal coating) 3 dimensional view of surface features on T.V. screen 100,000x

38. Scanning Electron Microscope uses reflected electrons to produce image

39. Images from a SEM Dentist Drill (x 50) Hypodermic Needle (x 100) Mosquito (x 100) Toilet Paper (x 500)

40. Phase Contrast: living cells Blood Cheek cell

41. WHICH SCOPE WOULD BE BEST TO USE TO LOOK AT: A pollen grain Mold on a piece of bread Bacteria Nucleus of a cell Grasshopper