Lab Report Experiment 2- Cell Staining PDF

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Summary

lab report for cell staining by group 1...

Description

Class Group :PI080S10 Lab Group’s No: Group 1

LABORATORY REPORT Experiment

Cell Staining

Lab Instructor’s Name

Malissa Mohamed

Date of Experiment

22 September 2021

Member 1

Muhammad Nurhakim Bin Hasnan (2021861026)

Member 2

Anis Sumaiyah Amal Ashraf (2021497002)

Member 3

Amirah Atikah Binti Mohd Azwar (2021873146)

Member 4

Nurulhusna Binti Mat Nayan (2021856762)

Member 5

Farah Nabila Bt Mohd Fadzil (2021881072)

Marks

CELL STAINING Farah Nabila Bt. Mohd Fadzil, Muhammad Nurhakim Bin Hasnan, Anis Sumaiyah Bt. Amal Ashraf, Amirah Atikah Bt. Mohd Azwar, Nurulhusna Bt. Mat Nayan

ABSTRACT

Cell staining is a useful technique to observe cell morphology and structure under a microscope. The objective of staining is to increase the contrast between the organisms and the backdrop so that they can be seen under a microscope more easily. Some commonly used stains for cell staining include methylene blue and safranin. Most stains can be used on non-living cells, while some can be used on living cells however only certain stains can be used on either living or non-living cells. A nucleus or a cell wall can be seen more clearly by using certain stains. In this experiment, stains that we used are iodine and methylene blue solution.

The main objective of this experiment is to observe stained plant and animal cells under the light microscope. For plant cells, we used onion cells. On the other hand, we used cheek cells and bacteria cells to observe the structure of animal cells. The proper staining techniques and wet mound could also be learned through this experiment. The results from this experiment showed that plant and animal cells have a different structure and components.

1) INTRODUCTION

All organisms are made of cells. Cells are the basic structural and functional units of every organism. Cells are microscopic which cannot be seen directly with our naked eyes because cells are extremely small. Basic features of cells are plasma membrane, cytosol, chromosomes and ribosomes. Cells can be classified into prokaryotes and eukaryotes.

Prokaryotic cells are organisms that do not have nucleus and membrane bound organelles. Prokaryotic cells can be classified into two domains which are Bacteria and Archaea. Meanwhile for eukaryotic cells, there are few characteristics to determine the type of cell. First it has DNA in the nucleus which is surrounded by a nuclear membrane. Next, eukaryotic cells is larger in size compared to prokaryotic cells

Eukaryotic cells can be classified into two types which are Unicellular eukaryotes and Multicellular eukaryotes. Unicellular eukaryotes like protozoa are microscopic which need to be observed under the microscope. Next, Multicellular eukaryotes can be divided into two which is plant cell and animal cell. We can differentiate these cells by observing the presence of cell walls and large vacuoles which are present in plant cells.

In this experiment we use onion cell as our plant cell and cheek cell as our animal cell and bacteria as our prokaryotic cell. This experiment is aimed to prepare a wet amount of plant cells and animal cells,to compare stained plant animal cells under the microscope and to observe prepared prokaryotic cells using immersion lens.

Objective 1. To prepare a wet amount of plant cells and animal cells 2.To compare stained plant and animal cells under the microscope.

Hypothesis

The theory why we use iodine to stain the onion epidermis is to enhance the visibility of the cells. The reason we use iodine to stain the onion epidermis instead of water is because onion is translucent which will be impossible to see if we use water to stain the onion epidermis. The organelles of onion cells that can be observed under the microscope are the clearly visible cell wall, cell membrane, vacuole, cytoplasm and nucleus. Although onion cells are plant cells, chloroplast cannot be observed because chloroplasts are largely present in the leafy part of onion.

Next, the theory why we use methylene blue solution to stain the cheek cell is to enhance the visibility of the nucleus of the cheek cell. The reason we use methylene blue solution instead of water to stain the cheek cell is because the cheek cell is transparent just like water. Thus it will be impossible to observe under the microscope. The organelle of cheek cells that can be observed under the microscope are nucleus,cytoplasm and cell membrane.

2) MATERIALS AND METHOD

Materials: Allium sp. (onion), Iodine stain and Methylene blue Apparatus: Scalpel, toothpick, forceps, microscope slide, microscope, cover slip, graticule and prepared slide- prokaryotes Method: Independent variable

i. Type of cell

Dependent variable

i. Image of the cell under 400x magnification

Controlled variable

i. Magnification used on each slide Ii. Surrounding environment

Procedure: Part I: Staining and observing plant and animal cells

A.

Onion cells i.

A small section of an onion, Allium sp. was cut

ii.

Forceps was used to peel off the thin, transparent epidermis

iii.

The onion epidermal was placed at the center of a microscope slide

iv.

A drop of Iodine stain was put on the epidermis. This is called a “wet mound”

v.

One edge of a cover slip was placed to one side of the stain and the cover slip was slowly lowered.

vi.

Excess stain was removed by using a paper towel by touching the edge of the cover slip.

vii.

Cells were examined under the microscope.

viii.

Cells that were observed under 400X magnification were drawn and labeled. Colour of the stained cells were stated.

B.

Cheek cells i.

One drop of methylene blue was placed at the center of a microscope slide

ii.

A toothpick was used to scrape lightly the inside of the cheek

iii.

The cells were smeared and mixed in the methylene blue solution

iv.

Steps v. to vii. was repeated

Part II: Observing prokaryotic cells 1.

A prepared slide was obtained from the instructor. The slide was labeled typical prokaryotic cells.

2.

The bacteria was observed at 400x magnification

3.

A picture of the cells was taken and was labeled accordingly

3) RESULTS

Labelled Diagram

Colour of Stained Cells

Part I (A) : Onion cells under 400X magnification

greenishbrown

Part I (B) : Cheek cells under 400X magnification

bluishpurple

Part II: Bacteria cells under 400X magnification

purple

4) DISCUSSION

In this cell staining experiment, we observed three different types of cells under the light microscope at 400x magnification which are plant cells, animal cells, and bacteria. Plant cells and animal cells are eukaryotic cells while bacteria are prokaryotic cells. We use onion epidermal cells as plant cells and cheek cells as animal cells. The differences between plant cells and animal cells are visible under a microscope. Therefore, we can easily distinguish between these two types of cells by observing them under a microscope.

Based on the result obtained, we found some organelles in the plant cells and animal cells can be observed under the light microscope. Referring to the stained onion cells that we observed at 400x magnification,we discovered organelles such as nucleus, cell wall, cell membrane and vacuole. Other organelles in the plant cells such as ribosomes, ER, and golgi apparatus, are invisible under the microscope since these organelles are considered as tiny organelles. A 400x magnification microscope is not sufficient to observe many tiny organelles, as it requires a higher magnification. While in the stained cheek cells, we observed cell membrane, cytoplasm and nucleus.

In preparing the wet mount of plant cells, we put one drop of iodine on the onion epidermal slide. Iodine stain is used to detect the presence of starch in the plant cells. Plants naturally form starches, polymer chains of individual glucose sugar molecules, to store extra energy during photosynthesis. Starch is made up of two components amylose and amylopectin that both curve into spiral shapes. Amylose is known as one long polymer chain and amylopectin is many individual chains attached in branching patterns.When soluble in water, solutions of iodine form complex iodide ions resulting in the change of color in the presence of starch. The ions get stuck in the spirals of starch polymer chains, forcing the iodide ions to become linear and change their electron arrangement that causes a color change. In the presence of amylose, the color becomes blue-black while in amylopectin it becomes a pale purple-red.

In preparing the wet mount of animal cells, we placed one drop of methylene blue solution in the center of a microscope slide and then mixed it with the cheek cells. Methylene blue is a popular alkaline stain used to stain animal cells to make nuclei more invisible or to enhance the appearance of the nucleus. Methylene blue binds with DNA and RNA by electrostatic means;

cells stained by methylene blue will show the nucleus with a deep blue color. Therefore, the image of the cheek cells can be clearly observed under the microscope.

5) CONCLUSION

As a conclusion, both stained plant and animal cells that were used in this experiment have achieved the objective as we can tell that the cells showed a different structure under the microscope. Also, we all get to know a proper and correct way of preparing a wet amount of plant cells and animal cells.

By referring to the result obtained, the cheek cells have no cell wall. Also, the vacuole in an animal cell is absent. In contrast to onion cells, the cell wall and large vacuoles were clearly observed under the microscope. A nucleus is located in the cytoplasm's center in both cells while the cytoplasm is surrounded by a cell membrane. The absence of a cell wall and the presence of a prominent vacuole are indicators that help identify animal cells, such as those found in the human cheek. Hence, the stated hypothesis was supported.

To conclude, cell staining is significant to observe structure in plant and animal cells because cells would appear almost transparent without stains, making it difficult to distinguish them. To enhance the visibility of the cells, stain solutions such as methylene blue solution and iodine were used.

6) REFERENCES

1. Flournoy, Blake. (2021, October 6). Lab Experiments to Test for the Presence of Starch When Using Potassium Iodine. sciencing.com. Retrieved from https://sciencing.com/lab-experiments-test-presence-starch-using-potassium-iodine-125 78.html 2. Jitendra Santija, (2018, December 11).Observation of Methylene Blue-stained Cheek Cells using Foldscope. https://microcosmos.foldscope.com/?p=98800 3. Introduction. (2020, September 25). Retrieved October 7, 2021, from https://bio.libretexts.org/@go/page/40261 4. Petersen, J., & McLaughlin, S. (2021, May 27). Introduction to Staining. Retrieved October 9, 2021, from https://bio.libretexts.org/@go/page/52240 5. Lab Demonstration | Experiment 2: Cell Staining | ASID BIOLOGY https://www.youtube.com/watch?v=_3FfCJu7YA8&list=PLG3c6XF_jW1CpJcJ7fYZrIIAN7 Z4P8Nny&index=5...