Experiment 3 Objectives: After completing the exercise, I was able to: a) Prepare the specimens for staining. b) Observe and identify the unique and typical structures of the microscopic world. c) Identify and use different stains for different types of organelles. Introduction Cell is the simplest unit of life as we see it now. All organisms are made from cells. It is first explained by Robert Hooke in the year 1665 and it is now known to be of almost universal occurrence in organisms. Cell theory refers to the idea that cells are the basic unit of structure in every living thing.
Development of this theory during the mid 1600s was made possible by advances in microscopy. In the hierarchy of biological organization, the cell is the simplest collection of matter that can live. There are diverse forms of life that exist as single-celled organism or complex organism. Though in general, most cells are similar, they still show considerable diversity especially in their contents, shape and function. However, with the creation of microscope, scientists and researchers are able to study the specimen of a cell and identify its different structure.
Big structures such as the cell wall, cell membrane and nucleus could be seen under the light microscope. Nevertheless, some smaller structures are still too small to be identified without first staining it. Stains can be used to enhance contrast in microscopy image. The choices of stain are important because different stains react or concentrate in different parts of a cell or tissue. This can be seen when acetocarmine stains the nucleus and its contents; iodine solution stains starch grains. Through this experiment, we will be able to determine the structures in the cell.
Results and Discussion I. Epidermal Cells of Plants Low power| | The diagram drawn is the upper layer of the cell of the Rheo Discolours leaf. From the diagram, we can see that the cells structured together, that is it seems to be a layer of over-lapped plant cells. Some of the cell have rhombus shaped object. Most of the cells have thick cell wall. After adding the stain iodine, the nucleus of the cell can be seen clearly on the few cells with a few smaller dark spots, that is the starch grains. High power| | The diagram drawn above shows the lower side of the Rheo Discolours leaf cells.
While the upper surface has the simple structures such as cell membranes, cell walls and vacuole, the lower structure consists of all that and also a clearer view of the epidermal cells of the leaf. When magnified, the guard cells and also the stomata. The guard cells are lip-shaped, surrounding the stomata. Most of the cells have thick cell wall, with signs of the parenchyma cells on the surface layer and the lower layer of the cell. There are signs of collenchymas especially when there are thickening around the edges of the cell wall when both corners are joined at the cell wall on both surfaces.
The lower surface have definitely larger amount of guard cells and stoma compare to the upper surface of the leave. The cell that contains green plastids is the guard cells which contain the chloroplast. II. Cell Wall and Middle Lamellae | The structure drawn above is the transverse section of celery cell. The cell wall is seen from the microscope, surrounding the structure and keeping it intact. A cross-section of a celery sample is composed of many cells. Transparent cells are in pith, vascular tissues and endodermis.
Endodermis is like a border between the inner and outer parts of a leaf. In the inner part of the leaf, the vascular tissue can be seen quite clearly grouped together, although the difference whether it is a xylem or phloem is indistinguishable. Collenchyma cell can also be seen in this cell when the walls are joined angularly at the corners. The fine channel in the cellulose that connects the adjacent cells is the plasmodemata. III. Yeast Cells (Saccharomyces) The cell drawn above is the structure of the yeast cell which is small when observed under the microscope.
Yeast is a tiny form of fungi or plant-like microorganism (visible only under a microscope) that exists in or on all living matter. Inside the yeast, one could see the nucleus, which are the dark colour dots, a liquid solution of protoplasm, protein, fat and mineral matter that the yeast is mainly composed of and the dark patches called the vacuole. However, it can be seen that the yeast cells do have irregular shaped cell walls. In a way, yeast cell resembles the plant cells as they also have a cell wall. Budding is a type of asexual reproduction commonly seen in yeast cells.
New individuals will arise from the outgrowths of existing ones. Budding allows the cell to grow without the fusion of the egg and sperm cell. Therefore, individual cells can also reproduce without a mate. I can conclude that yeast is neither a plant nor an animal cell; it is a type of fungi like mushroom. IV. Blood cells The structure above shows the drawing of the red blood cells. The red blood cells are so small that none of the structures are distinguishable. However, I could be sure that the red blood cell does not contain any nucleus. It is irregular in shape, so the cell wall is also absent.
The blood cells mostly clump together. They differ from the regular animal cell in the sense that it does not contain any nucleus whatsoever and it has no starch grains. The red blood cell is surrounded by a type of liquid, named the plasma. V. Spirogyra Cells The Spirogyra cells are cells that consist of a chain of elongated cells joined end to end. It consists of the basic structure seen in the plant cells, which is cell wall, cell membrane, nucleus, small starch grains and most importantly the chloroplast which is the most visible under the microscope.
The chloroplast consists of stacks of grana that can be seen clearly spiraling along the elongated cells. Chloroplast is important for the plant during photosynthesis as it converts sunlight and carbon dioxide into oxygen and energy. VI. Flagellum The cell drawn above is the Euglena cells. It is a one body cell that exists individually. It is very small even under the microscope and is barely visible even with staining. The euglena cell is green in colour. However it is not a plant cell because the shape is an irregular shape. Some of the Euglena has a tail structure that comes from the top of the cell.
This tail is called the flagellum. It seems that the flagellum is its mode of transport. Conclusion In a cell, whether an animal or a plant cells or cells from other groups in the animal kingdom, there are also smaller molecular structures that can only be seen with a high power microscope. Some structures require staining in order to be visible to the eye even with a microscope. Every staining is unique in order to see certain structures of the cell. Different types of cells have different structures and shapes. Every cell has their own special characteristics in these structures.