1. Observing Cells

2. Warm-up  Answer the following 3 questions on a sheet of paper:  Why are cells so small? (This was discussed in the video from yesterday)  What are the two major kinds of cells? (Hint: plant cells and animal cells are in the same category)  What is the most easily identifiable part of a cell?

3. Why are cells so small?  The explanation of why cells do not grow very large can be found in how cells function.  To carry out their work, cells need a constant supply of materials such as oxygen, water, and food particles. They also need to get rid of waste products.  A larger cell would need more materials and would produce more waste products.

4. Sizes and Shapes  Cells come in a variety of shapes and sizes. Most cells, however, fall into a narrow range of size- the “sweet spot” in which they function most effectively.  To grow bigger, organisms add more cells to their bodies instead of growing bigger cells.

5. Size and Shape We’ve learned that cells can’t be very big because they need to bring in food and get rid of waste through the cell membrane. Think of it this way: – Imagine a cell as a swimming pool with a diameter of 50 meters. To keep this “cell” alive, you must swim to the center of the pool carrying a beach ball (food), then swim back to the side carrying a life buoy (waste).Imagine you have to do this 12 times within a short span of time. What difference would it make it the pool had a diameter of 100 meters, and not 50?

6. Assignment 1  Colour the plant cell according to the directions on the sheet, and answer the questions at the bottom of the page.  The assignment is due at the end of class today. Don’t forget to write your name on your paper!