Introduction
In this experiment, we will learn to prepare the stained mount slides of onion peel and human cheek cells.
Experiment A
Aim
To prepare a temporary strained mount of onion peels and record your observation with a proper diagram.
Requirements
1. Onion,
2. Plain slides,
3. Coverslip,
4. Watch glass,
5. Needles,
6. Forceps,
7. Brush,
8. Blade,
9. Safranin,
10. Blotting paper,
11. Glycerine,
12. Compound microscope.
Theory
1. Onion comes under the category of a multicellular plant.
2. It has a cell membrane, cell wall, cytoplasm, a large vacuole, and a nucleus.
3. Vaculoe lies in the center, and the nucleus lies at the periphery of the cytoplasm.
4. Due to the presence of a cell wall and a vacuole, it is proved that onion cells are plant cells.
Procedure
Step 1: Take an onion piece and remove its epidermal piece, the transparent membrane that covers the onion.
Step 2: Using forceps, remove the inner peel of the onion. As shown in the figure.
Step 3: Place this peel in a watch glass filled with water.
Step 4: In this watch glass, place a few drops of strain safranin.
Step 5: Wash the leaf peel and put it into a clean slide using a brush.
Step 6: With the help of a blotting paper, remove the extra water surrounding the peel.
Step 7: Add a few drops of glycerine over the peel and cover it with a coverslip to avoid the entry of air bubbles.
Step 8: Using blotting paper, soak the extra water away.
Step 9: Now, using a microscope, observe this peel.
Observation
1. We can see a large number of cells with a rectangular shape with different cell walls.
2. Cytoplasm can be seen on the inner layer of the cell wall. It is a deep color substance.
3. A big vacuole will be seen at the center of the cell wall.
4. A nucleus will be seen in each cell wall.
Structure of an Onion Peel
Result
1. The epidermal piece of onion consists of cells of rectangular shapes. Each cell contains a nucleus, a cytoplasm, a vacuole, and a cell wall.
2. Cells of onion peel are plant cells because of the presence of a large vacuole and a cell wall.
Precautions
1. Always use a clean slide and be careful while holding it.
2. Peel the epidermic piece carefully.
3. Put the peel on the slide with the help of a brush.
4. Place the coverslip so that it does not let the air bubbles enter inside it.
5. Using blotting paper, remove the extra glycerine.
Experiment B
Aim
To prepare a temporary strained mount of human cheek cells and record your observation with a proper diagram.
Requirements
1. Slide,
2. Coverslip,
3. Needle,
4. Blotting paper,
5. Toothpick,
6. Methylene blue,
7. Watch glass,
8. Compound microscope.
Theory
1. Animal cells do not contain cell walls and vacuoles.
2. The cytoplasm is surrounded by the cell membrane in this cell.
3. Cytoplasm is denser and occupies a larger place in comparison to a plant cell.
4. Cheek cells are thin and flat and are a part of the squamous epithelium.
5. They are arranged end to end in such a way that it forms a delicate lining.
6. Nucleus is present at the center of the cell.
Procedure
Step 1: Rinse your mouth thoroughly to clear any food particles.
Step 2: To get an epithelial piece, scrap the inner side of the cheek using a toothpick.
Step 3: Place the scrapping on a slide. Put some water over it.
Step 4: Using a needle, spread the scrappings.
Step 5: Add a few drops of methylene blue over the scrapping.
Step 6: After waiting for two minutes, remove the extra scrappings from the slide.
Step 7: Add some glycerine over the slide.
Step 8: Now, place the coverslip over the slide to avoid the entry of air bubbles.
Step 9: Using a microscope, observe this slide.
Observation
1. You will see a large number of cells of polygon and irregular shapes.
2. This cell has a semi-permeable membrane called a cell membrane which contains a semi-fluid material called the contains cell membrane.
The Cell of a Human Cheek
Result
1. The cell on the specimen does not show a cell wall and a vacuole. So, the human cheek is an animal cell.
Precautions
1. Clean your mouth thoroughly so that it does not leave behind any food particles.
2. Always use a clean slide and be careful while holding it.
3. Scrap the cell carefully to avoid any kind of injury.
4. Place the coverslip so that it does not let the air bubbles enter inside it.
5. Using blotting paper, remove the extra glycerine.
6. Spread the scrapping for even distribution.
Conclusion
We have learned to prepare the stained mount slides of onion peel and human cheek cells in this way.
VIVA Questions With Answers
Q.1 What was the aim of our experiment?
ANS. To prepare the mount slides of onion peel and human cheek cells.
Q.2 Give a difference between the plant cell and the animal cell.
ANS. Plant cells have cell walls and a large vacuole, while animal cells do not have these.
Q.3 What do you mean by a cell wall?
ANS. The wall which encloses everything, such as cytoplasm, nucleus, etc., inside a plant cell is called a cell wall.
Q.4 What is the basic functional and structural unit of life?
ANS. Cell
Q.5 Name the thing which made the cell wall.
ANS. Cellulose
Q.6 Does the centrosome present in a plant cell?
ANS. No
Q.7 Plastids are present in which kind of cell?
ANS. Cell wall
Q.8 Name at least three organs that are present in both cells?
ANS. Nucleus, mitochondria, and ribosomes.
Q.9 Which organelles of a cell contain DNA?
ANS. Chloroplast and mitochondria.
Q.10 Which chemical is used for staining the human cheek cell?
ANS. Methylene blue
Saquib Siddiqui is a Mechanical Engineer and a content creator. He has special interest in science experiments and teaches the same to school and college students. He is also a technical lead at RUDE LABS PVT. LTD.
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