Practical Biology Biol 101Lab 2 Hail University Faculty of Sciences Department of Biology Microscope & Applications
Microscope Lab Objectives • Identify the parts of dissecting and compound light microscope and give their functions. • Coordinate their use to accurately focus on materials provided at the levels of magnification indicated on your response sheet without damaging the microscope or slides. • Demonstrate proper procedures for cleaning and preparing microscopes for use and returning them to their assigned storage place in proper condition.
Common Microscope Types Compound Binocular Electron microscope Dissecting
Microscope Type Uses • Dissecting microscope : • Allows one to study the entire object in three dimensions. (Examples: insects and leaves) • The compound light microscope : • Uses light rays which are magnified and focused by means of lenses. This type is used to examine tiny or thinly sliced cross sections. • Electron microscopes : • Uses a beam of electrons which are magnified on a photographic plate by means of an electromagnetic lens.
Compound Light Microscope Parts & Functions • Eyepiece: • Magnifies material being viewed by 10X • The part of the microscope you look into • Sometimes contains a pointer that can be seen as you look into the eyepiece. • May also be called the ocular.
Microscope Parts & Functions • Nose piece: • Part of microscope to which the objectives are attached • Rotates to allow for the changing of objectives to increase or decrease magnification.
Microscope Parts & Functions • Arm: • Part of microscope to which the nosepiece is attached • A secure part of the microscope to hold on to when the microscope is being carried. • Sometimes includes a cord hanger for power cord storage
Microscope Parts & Functions • Objectives: • Magnify material being examined • Scanning • magnifies 4X • 10X • magnifies 10X • High dry • magnifies 40X • Oil immersion • magnifies 100X Total magnification = magnifying power of eyepiece x The magnifying power of the objective in use.
Microscope Parts & Functions • Stage: • Platform on which microscope slide rests • Mechanical Stage: • Used for adjusting the position of the slide for viewing • Slide holder: • Secures slide to the mechanical stage • Mechanical Stage control knobs: • Move the slide
Microscope Parts & Functions • Coarse adjustment knob: • Coarse focusing • Fine adjustment knob: • Precise focusing
Microscope Parts & Functions • Substage condenser • concentrates light & directs it through opening in microscope stage • Iris diaphragm: • regulates the amount of light passing through the substage condenser • increases resolving power of the microscope
Microscope Parts & Functions • Iris diaphragm lever: • adjusts the iris diaphragm to increase or decrease microscope resolution • Condenser control knob: • raises & lowers condenser
Microscope Parts & Functions • Illuminator • Light source • Illuminator control: • Controls the intensity of light • Serves as the on/off switch for some microscopes • Base: • provides support for microscope
Microscope Cabinet Individual Storage Microscope Storage
Microscope Storage Always with a dust cover
Microscope Transport Always with one hand on the arm & one on the base.
Preparation for Storage • Clean microscope • Rotate shortest objective (4X) into place over stage • Lower stage for max distance between objective & stage • Wrap cord around base or on cord hanger
Preparation for Storage • Adjust mechanical stage so nothing sticks out from the sides • Replace dust cover • Return microscope to storage area
Preparation for Use • Transport microscope to work station • Remove dust cover • Plug in microscope • Inspect and clean microscope
Microscope Cleaning • Use only lens paper to clean glass parts of microscope. • Use glass cleaner with lens paper to remove immersion oil from objectives, etc. • Kimwipes or paper towels may only be used to clean microscope slides & non-glass parts of the microscope.
Prepare a wet mount using letter "e" from a newspaper. Obtain letter e and place it on a clean dry slide. Add a drop of water and cover with a cover slip by holding the cover slip at a 45o angle to the drop of water with one edge of the coverslip on the slide. Then gently and slowly lower the coverslip over the drop to get rid of air bubbles. Place your slide on the stage, and hold the slide in place by the clips. Be sure to have the structure to be examined over the opening of the stage.
Prepare a wet mount using letter "e" from a newspaper. Observe under the ocular and focus using the coarse adjustment knob until he image "e" is clear. Always begin your examination with the lowest power objective lens (4X). Make sure that the lens does not touch the slide. Once the structure is seen it may be necessary to adjust the amount of light by rotating the diaphragm slightly so that you get maximum illumination. Also, adjust the condenser. Use the fine adjustment knob to sharpen the focus if needed. When looking through the eyepiece, practice having both eyes open.
Unicellular organisms Paramecium