Question

study of animal cell. Experiment


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Answer 1

Explanation:

Human cheek cells

Materials:-

Glass microscope slides

Plastic cover slips

Paper towels or tissue

Methylene Blue solution (0.5% to 1% (mix approximately 1 part stock solution with 4 parts of water))

Plastic pipette or dropper

Sterile, individually packed cotton swabs

See information on suppliers here.

Methods:-

Take a clean cotton swab and gently scrape the inside of your mouth.

Smear the cotton swab on the centre of the microscope slide for 2 to 3 seconds.

Add a drop of methylene blue solution and place a coverslip on top. Concentrated methylene blue is toxic if ingested. Wear gloves and do NOT allow children to handle methylene blue solution or have access to the bottle of solution.

Remove any excess solution by allowing a paper towel to touch one side of the coverslip.

Place the slide on the microscope, with 4 x or 10 x objective in position and find a cell. Then view at higher magnification.

Methylene blue stains negatively charged molecules in the cell, including DNA and RNA. This dye is toxic when ingested and it causes irritation when in contact with the skin and eyes.

The cells seen are squamous epithelial cells from the outer epithelial layer of the mouth. The small blue dots are bacteria from our teeth and mouth.

Answer 2

Procedure :

• Gently scrape the inner side of the cheek using a toothpick, which will collect some cheek cells.
• Place the cells on a glass slide that has water on it.
• Mix the water and the cheek cells using a needle and spread them.
• Take a few drops of Methylene blue solution using a dropper and add this to the mixture on the slide.
• After 2-3 minutes remove any excess water and stain from the slide using a blotting paper.
• Take a few drops of glycerine using a dropper and add this to the test mixture.
• Take a clean cover slip and lower it carefully on the mixture with the aid of a needle.
• Using a brush and needle, press the cover slip gently to spread the epithelial cells.
• Remove any extra liquid around the cover slip using a blotting paper.
• Place this glass side on the stage of the compound microscope and view it.

Observations :

• A large number of flat and irregular-shaped cells are observed.
• The cells do not have a cell wall. However, each cell has a thin cell membrane.
• A deeply stained nucleus is observed at the centre of each cell.
• No prominent vacuoles are observed in the cells.

Conclusion :

• As the cells observed do not have a cell wall, nor a prominent vacuole, the cells of the specimen on the slide are animal cells.