OBJECTIVES
- To prepare temporary slide.
- To Show Plant Cell
- To Show cells of onion
MATERIALS REQUIRED
Fresh onion bulb, Safranin, Dropper, Glycerol, No. 0 painting round tip brush, forceps, needle, blade, scissor, wash bottle, petri dish, watch glass, cover glass, slide, compound microscope .
THEORY
Onion cells are commonly used for microscopic studies because they have large and easily observable cells. The onion cell has a rectangular shape and is enclosed by a cell wall. Inside the cell, you can find a nucleus and cytoplasm. Preparing a temporary slide of an onion cell allows us to observe these cellular structures under a microscope.
PROCEDURE
- Obtain a fresh onion bulb, that is free from damage or disease.
- Peel a thin, transparent layer from the onion bulb using a scalpel or razor blade. Try to get a layer that is as thin as possible.
- Cut the ventral peel in square about 3-4 mm length by scissor then keep in watch glass containing distilled water.
- Then transfer peel through brush to another watch glass containing 2-3 drops of Safranin and wait for 30 to 60 seconds.
- Then wash stain by transferring tissue to another watch glass containing clean distilled water for 2 or 3 times to remove stain completely.
- Take a clean microscope slide and pour a drop of glycerin at the center of slide.
- Then transfer tissue to slide containing glycerine.
- Then apply cover slip with needle to prevent bubble.
- Then watch under the compound microscope with 10X objective at first then at 45X objective.
- You find many stomata with guard cell, then draw diagram in practical note.
OBSERVATION
- The onion cells are typically rectangular or square in shape.
- A distinct cell wall surrounds each cell.
- A large central nucleus is visible within the cell.
- The cytoplasm fills the space between the cell wall and the nucleus.
- The iodine stain, if used, highlights the nucleus.
RESULT
A temporary slide of an onion cell has been successfully prepared and observed under the microscope. The cellular structures, including the cell wall, nucleus, and cytoplasm, were clearly visible.
CONCLUSION
Structure of onion cell in microscope successfully observed by making temporary slide.
PRECAUTIONS
- Handle the fresh onion peel with care to avoid damage or tearing.
- Ensure the microscope slide and coverslip are free from dust or debris.
- Take care not to introduce air bubbles between the peel and coverslip when mounting the slide.
- Don’t stain more than 1 minute to prevent over staining
- Keep leaf and peel in water to prevent dehydration.
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