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Onion Peel Cell Structure Study Cheat Sheet by

To observe and study the cell structure in an onion peel (cataphyll) using staining and mounting techniques.


To observe and study the cell structure in an onion peel (catap­hyll) using staining and mounting techni­ques.


Fresh onion bulb
Microscope slides
Cover slips
Safranin stain / Iodine solution (0.5%)
Distilled water


Step 1: Preparing the Onion Peel
1. Carefully peel off a thin, transl­ucent layer from the inner surface of an onion bulb (catap­hyll).
2.Place the onion peel on a clean microscope slide.
Step 2: Staining the Onion Peel
3. Using a dropper, add a few drops of safranin /0.5% iodine solution onto the onion peel. Ensure the entire surface is covered.
4. Allow the safranin / iodine solution to sit for 1-2 minutes to stain cell contents
Step 3: Mounting the Onion Peel
5. Gently lower a clean cover slip onto the onion peel, avoiding air bubbles. Angle it slightly to allow even spreading of safranin / iodine solution.
6. Press down gently to secure the cover slip.
Step 4: Microscope Observ­ation
7. Place the prepared slide on the microscope stage.
8.Start with the lowest objective lens (usually 4x or 10x) and focus using coarse and fine adjust­ments.
9. Increase magnif­ication (40x or 100x) and refocus as needed.
10. Observe onion peel cells, noting structures like cell wall, membrane, nucleus, and organelles
Step 5: Recording Observ­ations
11. Draw repres­ent­ative onion peel cells in your lab notebook. Label cell structures observed.
12. Note any variations in cell structure within the onion peel.
Step 6: Cleaning Up
13. Remove the slide from the microscope stage.
14.Dispose of onion peel and cover slip in designated waste container.
15. Clean microscope lenses and stage using lens cleaning paper and solution if needed.
Safety Precau­tions
Handle equipment and chemicals with care.
Be cautious with iodine solution, which can stain skin and clothing.
Wash hands thoroughly after the experi­ment.

Observ­ations: Safranin stained onion cells

Observ­ation Table

Cell Shape
Cell wall
Rigid, outermost layer
Cell Membrane (Plasma Membrane)
Thin, semi-p­erm­eable layer beneath the cell wall
Granular, semi-t­ran­spa­rent, filling the cell interior
Large, round, centrally located, darker staining
Large, clear, centrally located
Cell Arrang­ement
Regular pattern with adjacent cells
Variation in Cell Size
Some variations in cell size
Safranin / Iodine Staining
Effective staining of cell contents, enhancing visibility


This experiment allowed us to observe and study the cell structure of an onion peel using staining and mounting techni­ques. The iodine / safranin stain highli­ghted various cell compon­ents, including the cell wall, cell membrane, and nucleus. This observ­ation provides insight into the organi­zation and charac­ter­istics of plant cells.


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