Biology Project: Investigating Cell Organelles
In this chapter we are looking at cells, the basic units of life. Even though cells are the basic units, they are still organized and made of smaller structures. Just as the body is made of organs, each having different shapes and functions, so the cells are made of organelles, which also have their own shape and function. We will be studying the following organelles:
- endoplasmic reticulum
- golgi body
- lysosome and vacuole
The cell can be compared to a factory. Like a factory, it makes products that need to be packaged and delivered to places inside or outside the cell. It needs energy to make its products, and blueprints to work from. Our goal in this project will be to understand how these organelles work together to help the cell do its work.
We will be working in groups, each group being assigned to an organelle. The project requirements follow.
- Oral report: your group will prepare a five to seven minute oral report on your organelle. In your report, you should tell the class:
- What is the structure of your organelle? (What does it look like?)
- Where is it located in the cell?
- What does it do for the cell (what are its functions). You should be able to explain how what your organelle does for the cell is like a part of a factory. For example, you might tell us that the nucleus is like the main office, because all the decisions are made here. Explaining what the organelle does and how that fits in with the rest of the cell will take up most of your time in the presentation.
- When you give the report you should use either (1) the overhead (2) the chalkboard or (3) the computer to show your audience an outline of what you will say. Alternatively, the computer could be used for a PowerPoint presentation. This outline should also be written on paper, so that it can be handed in when you give your report (this is the only written component of your project)
- Each member of the group should be involved in the presentation.
- A physical model: your group will build a model that you will use during your presentation to show the class what your organelle looks like. The model should be constructed of materials that may be compared to both the structure and function of your organelle. For example, the cell membrane model might be thin and flat (like its structure). The mitochondria model might contain sugar (this would represent its function).
- the model will be displayed in the room after you make your presentations.
- the model should be three-dimensional
- be creative!
- include with your model a piece of poster board or index card that has written on it the name of the organelle and a one or several-word description of the organelle. The description might be factory comparison. For example, a sign might say "nucleus" and "main office"
The following books and other materials will be available for your research:
- Your textbook has short descriptions of each organelle; there are also several other textbooks available for you to use.
- The Web: start by looking at the "cell project resources" on Mr. Ausema's web site (http://www.cipce.rpi.edu/~ausemj/classroom.html). Explore these links to find:
- descriptions of some of the organelles
- electron micrographs (pictures taken with a microscope)
- Books from the school library.
- Several college-level textbooks are on reserve in the library. They must remain in the library.
- Pictures. In some of the books are electron micrographs, pictures taken with a powerful electron microscope. They might help you visualize what the organelle looks like. You can also find similar pictures on the web.
Some guidelines for proceeding:
- We will go to the library as a class to search for information that you might need. I recommend that you start by reading about your organelle in the textbook before searching for other sources.
- Once you have done some reading, brainstorm with your group members about how you might compare your organelle to a factory part, and how you might be able to explain to us what the organelle does. You might need to divide the labor - have each group member read more about one particular aspect of the organelle, or have one person work on the model and another on the oral presentation.
- Before your first research day is done make some decisions about how to build your model, and which members of your group will work on it.
- During the next few days of class, we will examine real cells with the microscope and images of cells with the computers. We will also conduct several experiments to help understand how membranes function. We will only have the one research day in the library.
Note to instructors: we do the following activities in our classroom time:
- Examine onion and elodea cells, using various stains, to get practice using microscopes and observing cell organelles. Students also learn how to make careful drawings and calculate their magnification. They also observe nuclei, chloroplasts, membranes, and walls.
- Conduct an experiment that demonstrates the effect of cell size on diffusion rate. The students learn that smaller cells can more easily use diffusion as a transport technique because of their greater surface area/volume ratio.
- Conduct experiments and/or class demonstrations that illustrate the principle of equilibrium and permeable membranes in diffusion. To demonstrate diffusion direction, we test the effect of sugar concentration on potato pieces. Potatoes will lose weight in concentrated sugar, but will gain wait in dilute sugar (concentrations ranging from 1.0 to 0.2 M). To demonstrate selective permeability, we use dialysis tubing, through which sugar will diffuse but starch will not.
Your grade for this assignment will be based on:
- How well your presentation (including the model and outline) clearly presents the structure and function of your organelle.
- A quiz (taken after the presentations), which will cover all of the organelles. The quiz will be open-note.
Your presentation will be graded with the following form (this is here for your information only - not to be filled out).
Biology Organelle Project -- grading sheet for presentations
|Names of team members:
|1. information presented
clear, precise, covers everything that it should
|2. presentation itself
understandable, everyone is involved
3D, displays all important info creative