Onion and Epithelial Cell Lab Exercise

Purpose

Equipment:

Procedure:

Note: After each section rinse and dry the slide and cover slip.

Onion

  1. Prepare an onion cell wet mount by pulling off a thin layer of cells between layers of an onion bulb.
  2. Sketch drawing as described in data section.
  3. Apply a single drop of iodine tincture to onion wet mount.
  4. Sketch drawing as described in data section.

Epithelial cell

  1. Prepare an epithelial cell wet mount by scraping the inside of your cheek with a clean toothpick.
  2. Sketch drawing as described in data section.
  3. Apply a single drop of iodine tincture to epithelial wet mount.
  4. Sketch drawing as described in data section.

Algae

  1. Prepare an algae cell wet mount using a minuscule piece of algae from class supply.
  2. Sketch drawing as described in data section.

Data Section:

  1. Drawing requirements:
    • Select and draw a few cells that are representative of the cells in the field of view (FOV).
    • The cells should also illustrate the relationships among the cells (tissue structure).
    • Each individual drawing should provide a level of detail and accuracy reflecting the approximately 3-5 minutes it takes for each drawing.
    • All drawings should use a petri dish as template for field of view.
    • Drawings are typically done at 400x. Label the drawing with the subject name, FOV and magnification.
  2. Create two each drawings of onion, one without stain and one with stain. (5 pts each).
  3. Create two each drawings of epithelial cells, one without stain and one with stain. (5 pts each).
  4. Create a drawing of algae cells without stain. (5 pts).

Analysis:

  1. What cell structures are found in both plant and animal cells? (2 pts).
  2. What structures can you see in the plant cell but not in the animal cell? (2 pts).
  3. What do you see with stain that you couldn't see without it? (2 pts).
  4. How do the cells compare in shape and size. (2 pts).
  5. What do you think you need to do to see more structures? (2 pts).