Observation of Plant & Animal Cells

Observation of Plant Cell

Aim:

To observe plant cells (Onion Cell) under a microscope and to identify cell membrane, cell wall, and nucleus.

Introduction :

An onion is a multicellular (consisting of many cells) plant organism.As in all plant cells, the cell of an onion peel consists of a cell wall, cell membrane, cytoplasm, nucleus and a large vacuole. The nucleus is present at the periphery of the cytoplasm. The vacuole is prominent and present at the centre of the cell. It is surrounded by cytoplasm. The presence of a cell wall and a large vacuole are indicators that help identify plant cells, such as seen in the onion peel.

Material Required:

·         Microscope

·         Microscope Slides

·         Cover slips

·         Dropper

·         Safranin

·         Paper towels

·         Onion Skin

·         Water

Procedure

• Pour some distilled water into a Petridish Lid.
• Peel off a leaf from half a piece of onion and using the forceps, pull out a piece of transparent onion peel (epidermis) from the leaf.
• Put the epidermis in the petri dish lid containing distilled water.
• Take a few drops of safranin solution in a dropper and transfer this into another petridish Lid.
• Transfer the peel into the watch glass containing the safranin solution.
• Let this remain in the Safranin solution for 30 seconds, so that the peel is stained.
• Take the peel from the Safranin solution and place it in the watch glass containing the distilled water.
• Take a few drops of glycerine in a dropper and pour 2-3 drops at the center of a dry glass slide.
• Place the peel onto the slide containing glycerine.
• Take a cover slip and place it gently on the peel with the aid of a needle.
• Remove the extra glycerine using a piece of blotting paper.
• Place this glass side on the stage of the compound microscope and view it.

Observations

• There are a large number of regularly shaped cells lying side by side and each cell has a distinct cell wall.
• A distinct nucleus is present on the periphery of each cell.
• Lightly stained cytoplasm is observed in each cell.
• A large vacuole is present at the centre of each cell, and is surrounded by the cytoplasm.

Conclusion

As cell walls and large vacuoles are clearly observed in all the cells, the cells placed for observation are plant cells.

Plant Cells (Microscopic Observation)

Observation of Animal Cell

Aim:

To observe animal cells (Cheek Cells) under microscope and  identify cell membrane, and nucleus of the cells.

Introduction

As in all animal cells, the cells of the human cheek do not possess a cell wall. A cell membrane that is semi-permeable surrounds the cytoplasm. Unlike plant cells, the cytoplasm in an animal cell is denser, granular and occupies a larger space. The vacuole in an an animal cell is smaller in size, or absent. The nucleus is present at the centre of the cytoplasm.The absence of a cell wall and a prominent vacuole are indicators that help identify animal cells, such as cells seen in the human cheek.

.Materials Required:

·         Microscope

·         Microscope Slides

·         Cover slips

·         Dropper

·         Cheek cells

·         Toothpick

·         Methylene blue stain

·         Paper towels

·         Water

 

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 (Saline) 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 excess water and stain by using 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.

 

Animal Cell (Cheek Cell)