Investigation 3 – Concept Day
Cellular Organization – Investigation 3
Note: In Lab, you will compare plant and animal cells using the light microscope. You will be able to see the primary differences between plant and animal cells first hand. You will observe that there are many similarities between the two types of cells but that plant cells are unique in having chloroplasts and a cell wall. You may also observe that plant cells have a large, dominant vacuole in their cytoplasm whereas animal cells do not.
In order to see greater detail than that described above, it takes significantly more magnification and resolution. This is achieved using the electron microscope. Only with this instrument can one clearly differentiate between different organelles within the cytoplasm of cells. Therefore, most of this presentation is devoted to showing you high magnification electron microscope photographs of plant and animal cells.
We also present an “idealized” model of both an animal and a plant cell. However, such models are not derived from images like you will have observed through your microscope, but through the use of electron microscopy. Once the plant and animal cell models are presented, their differences and similarities are depicted and a Venn diagram is presented. The final slide addresses the cellular functions of some of the organelles shown in models.
- Animal Cell: What You See. This simple slide shows the amount of detail that you are likely to see in animal cell preparations through your light microscope. While chromosomes are indicated on the illustration, these structures are only seen clearly in light microscopy in certain preparations of actively dividing cells.
Note: You will become much more familiar with the nucleus and chromosomes in the upcoming CELL, Cell Cycle and Cancer.
- As mentioned above, it is difficult or impossible to differentiate between the various cell organelles with the light microscope.
- Animal Cell: Electron Micrograph. This slide shows a Transmission Electron Microscope image of an animal cell with some of its organelles labeled. There are many mitochondria in this cell. By comparing many such images, scientists have been able to construct models of animal cells like the one shown in the next slide.
- Animal Cell: Model. This slide shows an idealized model of an animal cell. It is not meant to represent any particular type of animal cell and all animal cells are somewhat different from each other. It therefore simply depicts the common sub-cellular structures found in greater or lesser abundance in all animal cells.
Note: The final slide of this presentation includes a brief description of the functions of the various organelles shown in this model. It is also presented below for reference:
- Plant Cell: What You See. Turning now from animal to plant cells, this slide represents the structures that you are likely to see through your light microscope.
Note: As in the case with the animal cell, you will not be able to differentiate between the various organelles with the notable exception of the chloroplasts.
- Chloroplasts are the cellular site of photosynthesis and usually show up well in the light microscope. The cell wall and large water-filled vacuole should also be visable.
- Plant Cell: Electron Micrograph. This is a Transmission Electron Microscope image of a plant cell.
Note: You will not be able to see the Golgi apparatus and mitochondrion (singular for mitochondria) in the light microscope.
Note: There are other sub-cellular structures not labeled on this micrograph. Plant scientists have constructed models by examining many micrographs like the one shown here.
- Plant Cell: Model. This slide shows an idealized model of a plant cell. It is not meant to represent any particular type of plant cell and all plant cells are somewhat different from each other. It therefore simply depicts the common sub-cellular structures found in greater or lesser abundance in all plant cells.
- This slide simply shows the animal and plant cells together. Notice that each cellular structure, with the exception of the cell wall and chloroplasts, are present in both plant and animal cells.
- At the bottom of the slide, a Venn diagram is presented that once more highlights the similarities and differences between plant and animal cells.
Note: This slide simply lists the basic function of each of the cell organelles labeled or discussed in this presentation.