Biologists’ Tools & Technology Technology continually changes the way biologists work.

Magnifying Tools of a biologist. There are special tools a scientist might use to make things look bigger A. Microscope – used to enlarge objects that are extremely small, used to see fine detail. - 4 Types of Microscopes

Types of Microscopes 1. Light Microscope (LM) (also known as a compound microscope) The object has to be small and thin in order for light to pass through the object. Have many lenses that magnify the object. Can magnify an object up to 400 times its original size. Produce a 2-dimensional image. Show the actual color of the specimen.

Types of Microscopes Continued 2. Stereomicroscope (also known as a dissecting microscope) - Used to look at objects that are too large or thick and therefore light cannot pass through - Produces a 3-D image

Types of Microscopes Continued 3. Scanning Electron Microscope (SEM)– Uses high energy electrons in order to magnify objects that are too small to be seen by the naked eye. A computer produces a 3-D image and adds color. Can magnify objects more than 500,000 times its original size. These pollen grains taken on an SEM show the characteristic depth of field of SEM micrographs. An image of a house fly compound eye surface by using Scanning Electron Microscope SEM opened sample chamber video

Types of Microscopes Continued 4. Transmission Electron Microscope (TEM)– Transmits electrons through a thin slice of specimen. Shows a 2-D image. Colorized by computer. stoma

stoma stoma SEM LM stoma TEM

1. eyepiece - where you place your eye. Has a 10X magnification. 2. body tube - the tube that supports the eyepiece. It connects the eyepiece to the arm. 3. arm - this attaches the eyepiece and body tube to the base. Carry and hold the scope. 4. revolving nosepiece - the rotating device that holds the 3 objective lenses. 5. stage clips - metal clips that hold a slide securely onto the stage.

6. Objective lenses - low-power objective – (red color) small lens with a 4X magnification. total magnification = eyepiece x objective lens total magnification = (10X) x (4X) = 40X - Medium-power objective – (yellow color) medium lens with a 10X magnification. total magnification (10X) x (10X) = 100X - High-power objective – (blue color) large lens with a 40X magnification. total magnification (10X) x (40X) = 400X

7. stage - the platform on which a slide is placed. 8 7. stage - the platform on which a slide is placed. 8. coarse focus adjustment - a knob that makes large adjustments to the focus. Moves the stage up and down. 9. diaphragm - an adjustable opening under the stage, allowing different amounts of light onto the stage. 10. light source - this directs light upwards onto the slide. 11. fine focus adjustment - a knob that makes small adjustments to the focus (it is often smaller than the coarse focus knob). Makes the image clearer.

Tips for Using the Microscope 12. Power switch – turns microscope off and on. 13. Base – Supports the microscope. Tips for Using the Microscope Hold the slide by the edges; this prevents dirt from getting onto the slide. Use ONLY lens paper to clean a slide and coverslip. Use a coverslip to secure items onto the slide.

Tips for Using the Microscope Always start on low power (red). Use the coarse focus knob (the larger knob) to bring the item into focus. Center what you are looking at. Use the fine focus knob (smaller knob) to make the image clear. Then change the objective lens to medium power (yellow).

Tips for Using the Microscope 6. Use the fine focus knob. 7. If moving into high power (blue), change the objective lens and adjust the fine focus knob. 8. ALWAYS power off the microscope before unplugging. 9. CLEANUP – wrap cord around microscope, replace cover, and return to correct numbered spot in the cabinet. 10. Always carry the microscope with 2 hands; one under the base and the other on the arm.