Cell Division Simulation
The key to this activity is that students discover through their own observations that cells need to grow and make copies of their genetic material BEFORE dividing. In this activity, I give a couple of basic points about cell reproduction and then students do the activity:
1. Cells are the basic units of structure and function in living things. (We already discussed this concept in previous lessons)
2. Therefore, in all organisms, reproduction must somehow involve cells. (Discuss)
3. Cells themselves reproduce by splitting into two cells.
Activity
Materials
small zip lock bags (about 4X6 inches)
pasta, preferably spiral shape (any color) 8 pieces per bag
scissors
tape or stapler
Procedure
Ø Put the 8 pieces of pasta in the zip lock bag. Zip lock bag represents a cell and the pasta represents genetic material. Each individual piece of pasta is a single piece of information that cannot be cut in half: It must remain whole. Students should be reminded that whenever reproduction occurs, genetic material MUST pass from the parent to the offspring.
Ø Demonstrate one cellular division – cut bag in half, 4 pieces of pasta in each bag, re-seal bags with tape or staples.
Ø Students should continue the process of division as long as they can.
Results
Students will notice two things.
1) The cells get smaller and smaller.
At the end of the process, the pasta barely fits in the bag using the size I used (about 4X6 inches). If cells kept getting smaller and smaller, there wouldn’t be any room for the materials and processes that cells need to stay alive.
2) Only 8 divisions are possible.
Point out that humans have 46 pieces of pasta (you can introduce the word “chromosomes” here) or 23 pairs if you prefer. If cell division really happened as it did in our model, what would be the maximum number of cells a human could have? (46) How many cells do we actually have (50-75 trillion or so). So what do you think must happen to allow so many cells to be produced, when we started life as a single cell? (Cells must make copies of their genetic material before dividing). I point out that ALL of those pieces of pasta (chromosomes) must be handed down to the next generation because each one contains different pieces of information that the cell needs to stay alive.
Final Notes
4. Cells must do things before they divide:
a. grow
b. make copies of their genetic material
You might stretch this activity to include diagramming of the process and introduction of terms such as parent/daughter cells. Discuss chromosomes. Do a “Nesting Venn Diagram” from cells to genes (see below).
Nesting Venn Diagram
(Genes are part of DNA, which is a part of chromosomes, which are part of the nucleus, which is part of a cell)