How to Make a Hanging Drop Slide Copy

The "hang-drop" method allows the examination of a microorganism in its natural environment. This method allows the organism to maintain its natural shape and size. It also allows one to determine if the organism is motile (capable of moving itself).

Engaging Questions

  • How do you distinguish between Brownian movement and true mobility?

Teacher Goals

  • By using the "hang-drop" method, one will be able to determine if the organism being studied is motile (capable of moving itself).

Required Resources

  • Equipment:

    • concave microscope slide
    • coverslip
    • inoculating loop
    • vaseline
    • toothpick
    • solution with micro organisms
    • microscope
    • solvent (various alcohols work but purchased pigment solvents work best)

Steps

  1. Vaseline Seal

    Using a wooden toothpick, apply vaseline around the edge of the depression on a depression slide.

  2. Transfer

    Using an inoculating loop, transfer one or two loopfuls of bacterial broth or hay infusion onto a cover slip.

  3. Invert

    Invert the depression slide over the suspension on the coverslip.  Press on the slide gently to form a seal.

  4. Examine

    Lift the preparation and turn it right side up and examine it with a microscope under low power, then switch to high power.

Teacher Notes

  • Review with the class proper laboratory procedures for handling bacteria and using lab equipment. Circulate during the experiment to supervise and offer assistance where needed.

Learner Notes

  • Remember to use proper lab procedures. Clean your work station when finished. Thoroughly wash your hands.

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