FACULTY OF CHEMICAL ENGINEERINGMICROBIOLOGY LABORATORY (CBE 541)

NAME:MOHAMAD YUSOF BIN MOHD SALLEHUDDIN

MATRIC NO:2014411548

GROUP:EH2422A

LAB NO./TITLE OF EXPERIMENT:LAB 1 / MICROSCOPE

DATE PERFORMED:11 MARCH 2015

SEMESTER:2

PROGRAMME:EH242

LECTURER:MADAM NURUL ASYIKIN BINTI MD ZAKI

No.ContentAllocated MarksMarks Obtained

1. Abstract5

2. Introduction5

3. Objectives5

4. Theory 5

5. Procedures10

6. Apparatus5

7. Results and Calculations (if any)20

8. Discussions20

9. Conclusions10

10. Recommendations5

11. References5

12. Appendices 5

TOTAL100

Remarks:Checked by: Date:

............(MADAM NURUL ASYIKIN BINTI MD ZAKI)

TitlePage

1.0 ABSTRACT3

2.0 INTRODUCTION3 4

3.0 OBJECTIVES4

4.0 THEORY5 -7

5.0 PROCEDURES7 8

6.0 APPARATUS8

7.0 RESULTS AND CALCULATIONS9

8.0 DISCUSSIONS10

9.0 CONCLUSIONS11

10.0 RECOMMENDATIONS11

11.0 REFERENCES11

12.0 APPENDICES12 - 13

Table of Contents

1.0 ABSTRACTPlant cells and animal cells are eukaryotic cells as both have a nucleus. All plant cell consists of a cell wall, cell membrane, cytoplasm, nucleus and large vacuole. Animal cells are similar to plant cells. However, they lack cell wall and large vacuole. In this experiment 1, we are using optical microscope to observe onion skin cells and human cheek cells. We want to examine, to know the characteristic and to differentiate human cheek cells and onion skin cells. In this experiment, a small bit of an onion was cut off. The outermost and the thinnest layer of the onion was peeled. This layer is the onion skin cells. To obtain the cheek cells, the inside lining of the cheek was gently scraped with a sterile cotton swabs. Both onion skin cells and human cheek cells are placed on a glass slide respectively. Then, the glass slide was dropped with a few drops of safranin. The slides were observe under optical microscope with magnification of 100x, 400x, and 1000x. During observation, the onion skin cells have a fixed shape due to the presence of the cell wall. While animal cells have irregular shape due to absent of any cell wall. With the presence of cell wall, onion skin cells is classified as plant cells. Since human cheek cells lack any cell wall, they are classified as animal cells.

2.0 INTRODUCTIONAnton van Leeuwenhoek is regarded as the father of Microbiology. His vast contribution in Microbiology allows him to receive that title. In 1673, Leeuwenhoek discovered the existence of microorganism. He used a simple microscope consist of a single biconcave lens to aid in his discovery. This discovery sparks a new beginning of Microbiology. Microscope has undergoes drastic changes throughout the time. Starting with the simple microscope created by Leeuwenhoek with magnification of 300x, to the powerful electron microscope with magnification of more than 250000x. This shows how important microscope in Microbiology to observe the microorganism (Cappuccino & Sherman, 2008).In this experiment, optical microscope was used to observe the onion skin cells and human cheek cells. Onion and cheek cells were observed under optical microscope at a magnification of 100x, 400x and 1000x. We also want to observe the cell shape and several organelles of the cells. When observed under the optical microscope, the cell shape and organelles of onion and cheek cell should be slightly different. These characteristics may classify them either as plant cell or animal cell.To obtain the onion skin cells, a small bit of the onion was cut off. Onion skin was ripped carefully from the onion bit until the smooth and thin white layer was peeled off. Then, the white layer was carefully spread out on the glass slide. A few drops of distilled water were dropped on the slide. Then, a few drops of safranin were dropped on the slide. Cover slip is carefully placed on the glass slide to avoid formation of air bubbles. A piece of tissue is used to remove excess solution on the glass slide. Then, the slide was placed on the stage of the microscope to prepare for observation. The observation is started with magnification of 100x. Then, the magnification is changed to 400x and 1000x. The focus knob was adjusted to obtain the clearest image possible. The structures, organelles and shape of the cell were observed.Meanwhile, the human cheek cells were obtained by scrapping the inside of the cheek with sterile cotton swab. It should be scrapped gently so to avoid hurting the cheek. Then, a few drops of distilled water were dropped on the glass slide. The sterile cotton swab was gently rolled on the glass slide. Then, a few drops of safranin were dropped on the slide to stain the cheek cell. Cover slip is carefully placed on the glass slide to avoid formation of air bubbles. A piece of tissue is used to remove excess solution on the glass slide. Then, the slide was placed on the stage of the microscope to prepare for observation. The observation is started with magnification of 100x. Then, the magnification is changed to 400x and 1000x. The focus knob was adjusted to obtain the clearest image possible. The structures, organelles and shape of the cell were observed.

3.0 OBJECTIVES1. To examine human cheek cells and onion skin cells.2. To know the characteristic of plant cells and animal cells.3. To differentiate between plant cells and animal cells.

4.0 THEORYOptical microscope contains ocular lens in the eyepiece and objective lens in the nosepiece. The specimen is illuminated by light from the condenser. Since it is difficult to distinguish between the specimen and the surrounding, the specimen is usually stained. The calculation for magnification of optical microscope:

MagnificationTotal Magnification

Objective lensesOcular lenses

Scanning 4x10x40x

Low-power 10x10x100x

High-power 40x10x400x

Oil-immersion10x1000x

Table of Magnification of Optical Microscope

Onion CellAn onion is a multicellular plant organism. The onion epidermis contain plant cells which is present in all plants. All plant cells consist of a cell wall, cell membrane, cytoplasm, nucleus and vacuole. A cell membrane is semi-permeable and surrounds the cytoplasm. The nucleus controls the metabolic rate of the cell, is located near the vacuole in the cytoplasm. The vacuole has the largest size in the cytoplasm and usually located at the centre of the cell. Both nucleus and vacuole is surrounded by cytoplasm. The presence of a cell wall and a large vacuole are key points that help recognise plant cells, such as in the onion epidermis.Plant cells are similar to animal cells in that they are both eukaryotic cells and have similar organelles. Plant cells are generally larger than animal cells. While animal cells come in various sizes and tend to have irregular shapes, plant cells are more similar in size and are typically rectangular or cube shaped. A plant cell also contains structures not found in an animal cell. Some of these include a cell wall, a large vacuole, and plastids. Plastids, such as chloroplasts, assist in storing and harvesting needed substances for the plant (Bailey, 2015).

Human Cheek CellThe human cheek cell is an animal cell. All animal cells consist of a cell membrane, cytoplasm, and nucleus. A cell membrane is semi-permeable and surrounds the cytoplasm. At the centre of the cytoplasm the nucleus is usually located. Unlike plant cell, animal cell does not have a cell wall, it only have a cell membrane. Compare to the plant cell, the vacuole in an animal cell is smaller in size and sometimes it may be absent. The absence of cell wall are indicators that helps to differentiate between animal cells and plant cells, such as cells seen in the human cheek.Animal cells are similar to plant cells in that they are both eukaryotic cells and have similar organelles except chloroplast. Animal cells are generally smaller than plant cells. Animal cells come in various sizes and tend to have irregular shapes, while plant cells are more similar in size and are typically rectangular or cube shaped. Animal cells also contain structures such as centrioles, lysosomes, and cilia and flagella that are not typically found in plant cells (Bailey, 2015).Cell WallThe presence of a cell wall is the most important key to differentiate between plant and animal cells. This is because it is only present in plant cells. Animal cell lack cell wall. The cell wall enclosed the cell membrane of the plant cell. It is rigid and is composed of cellulose fibre, polysaccharides, and proteins. This rigidity also helps plant cell to obtain a fixed shape, usually rectangular shape. Despite the rigidity of the cell wall, chemical signals and cellular excretions are allowed to pass between cells.Cell MembraneThe cell membrane is found in both plants and animals cell. It is the outer most layer in the cell that separates the cytoplasm of the cell from the outside substances. It consists of both lipids and proteins and is selectively permeable. This means it permits only some molecules to pass through it.CytoplasmCytoplasm is a jelly-like material that is eighty percent water and is usually colourless. It is also called cytosol. Cytoplasm contains all the organelles and it is enclosed by cell membrane. It also contains dissolved nutrients and helps break down waste products by using enzymes.NucleusThe nucleus and acts as the control centre of the cell. It is responsible to regulate all the activities inside the cell. Usually, it is the largest organelle in the cell. However, for most plant cell, nucleus is the second largest organelle after vacuole. The nucleus also contains the DNA of the cell. DNA contains all the information that helps cells live, perform their functions and reproduce. The nucleus has a double layered membrane called nuclear membrane.VacuolesA vacuole is a membrane-bound organelle that contains solid or liquid contents. Vacuoles are found in both animal and plant cells, but are much larger in plant cells. In fact, for most plant cell, it is the largest organelle. In animal cell, vacuole is small and sometimes it may be absent. Vacuoles are formed by the fusion of multiple membrane vesicles and are just larger forms of these vesicles. It has no basic shape or size; its structure varies according to the needs of the cell (Saxena & Saxena, 2010).

5.0 PROCEDURESPLANT CELL1. A small bit of an onion was cut off. The outermost and the thinnest layer of the onion was peeled. This layer should be thin enough to be translucent.2. The specimen, which is the thin onion skin was placed on the glass slide and a few drops of distilled water were dropped.3. A few drops of safranin were dropped on the glass slide and the glass slide was covered by cover slip carefully to ensure no air bubbles were formed.4. The glass slide was placed on the stage of microscope and clipped to stay in place.5. The observation of the specimen was started with magnification of 100x, 400x and 1000x.6. The focus knob was adjusted to obtain clearer image.7. The specimen was observed and drew.ANIMAL CELL1. The inside lining of the cheek was gently scraped with a sterile cotton swabs.2. A few drops of distilled water were dropped on the glass slide and the sterile cotton swabs was gently tapped on the glass slide.3. A few drops of safranin were dropped on the glass slide and it was covered carefully with cover slip to prevent air bubbles.4. The glass slide was placed on the stage of microscope and clipped to stay in place.5. The observation of the specimen was started with magnification of 100x, 400x and 1000x.6. The focus knob was adjusted to obtain clearer image.7. The specimen was observed and drew.

6.0 APPARATUSApparatusFunction

Optical microscope To observe the specimen with various magnification.

Onion skin The specimen which contain plant cells that will be used to be observed under the microscope.

Cheek cell The specimen that will be used to be observed under the microscope.

Glass slide Small slide which allow specimen to be placed on it.

Cover slip A thin and transparent plastic slip to cover the specimen on the glass slide

Safranin Used to stain the cells to be observed better under the microscope.

Distilled water To wet the specimen on the glass slide

Razor knife Sharp knife to cut the onion.

Sterile cotton swabs Swabbed inside the cheeks to obtain cheek cells

7.0 RESULTS AND CALCULATIONS

MagnificationPlant cellAnimal cell

100x

400x

1000x

8.0 DISCUSSIONIn this experiment, only nucleus, cytoplasm, cell wall, and vacuole were visible under optical microscope. This however, is enough to know the characteristic of onion skin cells and human cheek cells. Smaller organelles such as mitochondria can only be seen under electron microscope.Next, I have found that the cheek cells have irregular shape. This is due to the lack of cell wall that can maintain a fixed shape. They also seem to be circular or oval in shape. Since they lack of cell wall, this means that cheek cells are animal cells, not plant cells. Inside the cytoplasm, there is a nucleus at the centre of the cheek cells. The cheek cells are scattered randomly on the slide surface. Also, the size varies slightly between each cells. Next, the cheek cells are also lack of visible vacuole. Hence, I have determined that cheek cells are animal cells.For the onion skin cells, I have found that it have a fixed shape and it closely resembles a rectangle. The shape occurs due to the presence of the cell wall. This characteristic prove that onion cheek cells are plant cells due to the presence of cell wall. Unlike animal cells, the onion skin cells are positioned next to each other. Perhaps the fixed shape allows them to form such arrangement. Inside the cytoplasm, there is a nucleus at the centre of onion skin cell. I have noticed that the onion skin cell lack chloroplast. This shows that onion skin cell is an epidermal cell. Hence, I have determined that onion skin cells are plant cells (St. Rosemary Educational Institution, 2011).In this experiment, I have found some differences between human cheek cells and onion skin cells. Onion skin cells have cell wall while the cheek cell doesnt. Next, onion skin cells have a fixed shape, while the cheek cells have an irregular shape. Also, the arrangement for onion skin cells are next to each other. While for human cheek cells, they are randomly placed.Besides that, I have also found similarities for both onion skin cells and human cheek cells. Both are eukaryotic cells as shown by the presence of nucleus. Both have cytoplasm and cell membrane.

9.0 CONCLUSIONSOnion skin cells are plant cells since they have a cell wall. Onion skin cells also have a fixed shape due to the presence of cell wall. They seem to be rectangular in shape. They are also arranged closely next to each other. For human cheek cells, they are animal cells because they lack cell wall. Human cheek cells have irregular shape. They seem to be circular or oval in shape. They are also randomly scattered. Both plant and animal cell are eukaryotic cells as shown by the presence of nucleus. Besides that, both of them have cell membrane, and cytoplasm. Only onion cheek cell have the cell wall.10.0 RECOMMENDATIONSAt the end of this experiment, I have found that the results are similar with the theory. For plant cells, I managed to observe cell wall, cell membrane, cytoplasm and vacuole clearly under optical microscope. For animal cells, I managed to observe cell membrane, and cytoplasm clearly under optical microscope. When preparing the slides, I have noticed that there are presence of some air bubbles. To avoid unwanted air bubbles, one end of the cover slip should be placed on the slide. Then, slowly lower the other end using the end of a toothpick. This will help to prevent air bubbles from getting trapped under the cover slip.

11.0 REFERENCES1. St. Rosemary Educational Institution. (2011). Plant & Animal Cells Staining Lab Answers. Retrieved from the St. Rosemary Educational Institution website: http://schoolworkhelper.net/plant-animal-cells-staining-lab-answers/2. Bailey, R. (2015). Plant Cell. Retrieved from the About Education Website: http://biology.about.com/od/cellbiology/ss/plant-cell.htm3. Bailey, R. (2015). All about Animal Cells. Retrieved from the About Education website: http://biology.about.com/od/cellbiology/ss/animal_cells.htm4. Saxena, S. P., & Saxena, D. (2010). Comprehensive Practical Science. New Delhi: Laxmi Publications P.Ltd5. Cappuccino J., & Sherman N. (2008). Microbiology: A Laboratory Manual. San Francisco, CA: Pearson Education, Inc., publishing.

Plant CellAnimal cell12.0 APPENDICES

Optical Microscope3