Study of Cell Structure by Temporary Mounts of an Onion Peel

 

Experiment No:

Study of Cell Structure by Temporary Mounts of an Onion Peel

 

Objective:

To prepare a stained temporary mount of an onion peel and to record observations and draw labeled diagrams.

Apparatus and materials required:

Onion, glass-slide, watch glass, cover slip, forceps, needles, brush, blade, filter paper, safranin, glycerine, dropper, water, and a compound microscope.

 Theory:

All living organisms are made up of cells. The shape, size and the number of these units vary in organisms. The three major components of a cell are the cell membrane, cytoplasm and nucleus. In a plant cell, a cell wall surrounds the cell membrane.

 Procedure:

1.  Take an onion and remove its outer most peel.

2.  Now cut a small part from an inner scale leaf with the help of a blade.

3.   Separate a thin, transparent peel from the convex surface of the scale leaf with the help of forceps.

4.  Keep this peel in a watch glass containing water

5.  Add two drops of safranin stain in the watch glass to stain the peel.

6.  Take a clean slide and put a drop of glycerine in the centre of the slide. Glycerine prevents the peel from drying up.

7.  With the help of a brush and needle transfer the peel on the slide.

8.  Carefully cover it with a cover slip and avoid any air bubble from entering the cover slip.

9.  Remove any excessive glycerine with a filter paper.

10.  Observe the prepared mount of the peel under the low and high magnification of a compound microscope.

Observations:

A large number of rectangular cells are visible. These cells lie close to each other with intercellular spaces between them. These cells are surrounded by distinct cell walls. These cells have a dark stained nucleus and a large vacuole in the centre.

 Result:

how to draw onion cell step by step/onion cell drawing

https://www.youtube.com/watch?v=Qk41LkaPFAA

Fig 1: Cells of Onion peel

 

Add your observation

Fig 2: Microscopic view of cells of Onion peel

 

Precautions:

1.  Over staining and under-staining should be avoided.

2.  Folding of the peel should be avoided.

3.  Clean and dry glass slide and cover slip should be used.

4.  Cover slip should be put carefully avoiding any air bubbles.

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