Microscopes How can we observe cells?

What technology allows biologists to study microscopic life? A. Compound Light Microscope Has two lenses – ocular (eyepiece) and objective In order to be viewed, specimen must be thin (so the light may shine through the specimen) and placed on a slide. Specimen may be stained to better see structures

Fill It In … Label the ocular lens and the objective lens:

Ocular lens (Eyepiece) Body Tube Nosepiece Arm Objectives Stage Stage Clips Coarse Adjustment Diaphragm Fine Adjustment Light Always carry a microscope with one hand holding the arm and one hand under the base. Base

What technology allows biologists to study microscopic life? B. Electron Microscope Uses electrons to produce an image Types: Scanning Electron Microscope (SEM) Electrons scan the surface of a specimen Produces a 3-D image

What technology allows biologists to study microscopic life? B. Electron Microscope Transmission Electron Microscope (TEM) Designed to look at structures inside a cell Capable of greatest magnification

What technology allows biologists to study microscopic life? C. Limitations of microscopes Magnification is limited by the strength of the lens. Calculating magnification: Ocular lens x objective lens = total magnification Example: Ocular (10x) x objective (40x) = 400x As magnification increases resolution/(sharpness) decreases.

What’s my power? To calculate the power of magnification, multiply the power of the ocular lens by the power of the objective. What are the powers of magnification for each of the objectives we have on our microscopes?

Comparing Powers of Magnification We can see better details with higher the powers of magnification, but we cannot see as much of the image. Which of these images would be viewed at a higher power of magnification?

Check Yourself! Why must specimens be thin for a compound light microscope? Which microscope provides the highest possible magnification? If the ocular lens is 10x and the objective lens is 10x then the total magnification is? As magnification increases, resolution _______________

Check Yourself! Why must specimens be thin for a compound light microscope? TO ALLOW LIGHT TO PASS THROUGH THE SPECIMEN Which microscope provides the highest possible magnification? If the ocular lens is 10x and the objective lens is 10x then the total magnification is? As magnification increases, resolution _______________

Check Yourself! Why must specimens be thin for a compound light microscope? TO ALLOW LIGHT TO PASS THROUGH THE SPECIMEN Which microscope provides the highest possible magnification? TEM (TRANSMISSION ELECTRON) If the ocular lens is 10x and the objective lens is 10x then the total magnification is? As magnification increases, resolution _______________

Check Yourself! Why must specimens be thin for a compound light microscope? TO ALLOW LIGHT TO PASS THROUGH THE SPECIMEN Which microscope provides the highest possible magnification? TEM (TRANSMISSION ELECTRON) If the ocular lens is 10x and the objective lens is 10x then the total magnification is? 10 X 10 = 100X As magnification increases, resolution _______________

Check Yourself! Why must specimens be thin for a compound light microscope? TO ALLOW LIGHT TO PASS THROUGH THE SPECIMEN Which microscope provides the highest possible magnification? TEM (TRANSMISSION ELECTRON) If the ocular lens is 10x and the objective lens is 10x then the total magnification is? 10 X 10 = 100X As magnification increases, resolution _DECREASES_

Cheek Cells!